Synthetic organic reactions that use reactions between unsaturated molecules to form cyclical products.
Changing an open-chain hydrocarbon to a closed ring. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
Hydrocarbons with at least one triple bond in the linear portion, of the general formula Cn-H2n-2.
Organic chemistry methodology that mimics the modular nature of various biosynthetic processes. It uses highly reliable and selective reactions designed to "click" i.e., rapidly join small modular units together in high yield, without offensive byproducts. In combination with COMBINATORIAL CHEMISTRY TECHNIQUES, it is used for the synthesis of new compounds and combinatorial libraries.
Rhodium. A hard and rare metal of the platinum group, atomic number 45, atomic weight 102.905, symbol Rh. (Dorland, 28th ed)
The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
Organic or inorganic compounds that contain the -N3 group.
Acyclic branched or unbranched hydrocarbons having two carbon-carbon double bonds.
Unsaturated hydrocarbons of the type Cn-H2n, indicated by the suffix -ene. (Grant & Hackh's Chemical Dictionary, 5th ed, p408)
The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.
A plant genus of the family MENISPERMACEAE. Members contain sinomenine, caffeine, 1,7-dimethylxanthine, and other ALKALOIDS.
Organic compounds that contain GOLD as an integral part of the molecule. Some are used as ANTIRHEUMATIC AGENTS. The term chrysotherapy derives from an ancient Greek term for gold.
The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.
SESQUITERPENES cyclized into two adjoining rings, one being 7-carbons and the other is 5-carbons.
A group of compounds consisting in part of two rings sharing one atom (usually a carbon) in common.
A technology, in which sets of reactions for solution or solid-phase synthesis, is used to create molecular libraries for analysis of compounds on a large scale.
Carbonic acid (H2C03). The hypothetical acid of carbon dioxide and water. It exists only in the form of its salts (carbonates), acid salts (hydrogen carbonates), amines (carbamic acid), and acid chlorides (carbonyl chloride). (From Grant & Hackh's Chemical Dictionary, 5th ed)
Saturated indolizines that are fused six and five-membered rings with a nitrogen atom at the ring fusion. They are biosynthesized in PLANTS by cyclization of a LYSINE coupled to ACETYL COENZYME A. Many of them are naturally occurring ALKALOIDS.
A heavy metal trace element with the atomic symbol Cu, atomic number 29, and atomic weight 63.55.
Organic compounds composed exclusively of carbon and hydrogen forming a closed ring that may be either alicyclic or aromatic.
Alicyclic hydrocarbons in which three or more of the carbon atoms in each molecule are united in a ring structure and each of the ring carbon atoms is joined to two hydrogen atoms or alkyl groups. The simplest members are cyclopropane (C3H6), cyclobutane (C4H8), cyclohexane (C6H12), and derivatives of these such as methylcyclohexane (C6H11CH3). (From Sax, et al., Hawley's Condensed Chemical Dictionary, 11th ed)
The characteristic three-dimensional shape of a molecule.
Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions. Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity. Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis. Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant & Hackh's Chemical Dictionary, 5th ed, p301, p499)
A chemical element having an atomic weight of 106.4, atomic number of 46, and the symbol Pd. It is a white, ductile metal resembling platinum, and following it in abundance and importance of applications. It is used in dentistry in the form of gold, silver, and copper alloys.
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).
A group of compounds with an 8-carbon ring. They may be saturated or unsaturated.
A plant genus of the family APOCYNACEAE. It contains ellipticine.
OXADIAZOLES bearing an oxygen at the 5-position. They are mesoionic, with delocalized positive and negative charges.
Ring compounds having atoms other than carbon in their nuclei. (Grant & Hackh's Chemical Dictionary, 5th ed)
Compounds with a 5-membered ring of four carbons and an oxygen. They are aromatic heterocycles. The reduced form is tetrahydrofuran.
Organic compounds that contain the -NCO radical.
Group of alkaloids containing a benzylpyrrole group (derived from TRYPTOPHAN)
A major alkaloid of Vinca minor L., Apocynaceae. It has been used therapeutically as a vasodilator and antihypertensive agent, particularly in cerebrovascular disorders.
Azoles with an OXYGEN and a NITROGEN next to each other at the 1,2 positions, in contrast to OXAZOLES that have nitrogens at the 1,3 positions.
The study of the structure, preparation, properties, and reactions of carbon compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
The theory that the radiation and absorption of energy take place in definite quantities called quanta (E) which vary in size and are defined by the equation E=hv in which h is Planck's constant and v is the frequency of the radiation.
Six-membered heterocycles containing an oxygen and a nitrogen.
The conformation, properties, reaction processes, and the properties of the reactions of carbon compounds.
Liquids that dissolve other substances (solutes), generally solids, without any change in chemical composition, as, water containing sugar. (Grant & Hackh's Chemical Dictionary, 5th ed)
A chlorinated hydrocarbon that has been used as an inhalation anesthetic and acts as a narcotic in high concentrations. Its primary use is as a solvent in manufacturing and food technology.

Total synthesis of (+)-nankakurines A and B and (+/-)-5-epi-nankakurine A. (1/73)

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Tyrosine-lipid peroxide adducts from radical termination: para coupling and intramolecular Diels-Alder cyclization. (2/73)

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Interception of a Rautenstrauch intermediate by alkynes for [5+2] cycloaddition: rhodium-catalyzed cycloisomerization of 3-acyloxy-4-ene-1,9-diynes to bicyclo[5.3.0]decatrienes. (3/73)

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Increasing the efficacy of bioorthogonal click reactions for bioconjugation: a comparative study. (4/73)

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The chemical synthesis of tetrodoxin: an ongoing quest. (5/73)

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Detection of transglutaminase activity using click chemistry. (6/73)

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Total synthesis of (+/-)-sorocenol B employing nanoparticle catalysis. (7/73)

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Effects of trehalose polycation end-group functionalization on plasmid DNA uptake and transfection. (8/73)

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Determining small molecule-target protein interaction is essential for the chemical proteomics. One of the most important keys to explore biological system in chemical proteomics field is finding first-class molecular tools. Chemical probes can provide great spatiotemporal control to elucidate biological functions of proteins as well as for interrogating biological pathways. The invention of bioorthogonal chemistry has revolutionized the field of chemical biology by providing superior chemical tools and has been widely used for investigating the dynamics and function of biomolecules in live condition. Among 20 different bioorthogonal reactions, tetrazine ligation has been spotlighted as the most advanced bioorthogonal chemistry because of their extremely faster kinetics and higher specificity than others. Therefore, tetrazine ligation has a tremendous potential to enhance the proteomic research. This review highlights the current status of tetrazine ligation reaction as a molecular tool for the chemical
Determining small molecule-target protein interaction is essential for the chemical proteomics. One of the most important keys to explore biological system in chemical proteomics field is finding first-class molecular tools. Chemical probes can provide great spatiotemporal control to elucidate biological functions of proteins as well as for interrogating biological pathways. The invention of bioorthogonal chemistry has revolutionized the field of chemical biology by providing superior chemical tools and has been widely used for investigating the dynamics and function of biomolecules in live condition. Among 20 different bioorthogonal reactions, tetrazine ligation has been spotlighted as the most advanced bioorthogonal chemistry because of their extremely faster kinetics and higher specificity than others. Therefore, tetrazine ligation has a tremendous potential to enhance the proteomic research. This review highlights the current status of tetrazine ligation reaction as a molecular tool for the chemical
TY - JOUR. T1 - Carbene and silicon routes as methods for the generation and dipolar cycloaddition reactions of methyl nitrile ylide. AU - Padwa, Albert. AU - Gasdaska, John R.. AU - Tomas, Miguel. AU - Turro, Nicholas J.. AU - Cha, Yuan. AU - Gould, Ian. PY - 1986. Y1 - 1986. N2 - Methyl nitrile ylide was generated by both a photochemical and desilylation route and has been characterized by UV spectroscopy and by its kinetic and cycloaddition behavior. The dipole is formed by the addition of singlet methylene to acetonitrile and shows a strong transient absorption at 280 nm which is quenched by the addition of standard dipolarophiles. The relative rates of formation of 1,3-dipolar adducts and the relative rates of quenching of the transient absorption are in excellent agreement. Generation of the dipole from a silylthioimidate followed by dipolar cycloaddition also gave rise to related cycloadducts. The ratio of cycloadducts obtained from an unsymmetrically substituted dipolarophile was found ...
The 1,3-dipolar cycloaddition reaction of cyclopropanes and nitrones to give tetrahydro-1,2-oxazine has been studied with density functional theory calculations at the B3LYP/6-31+G(d,p) level of theory. Realistic substituents were modelled including those at the 2-, 3-, 4-, and 6-positions of the final oxazine ring product. The strained σ bond of the cyclopropane was found to play the role of an alkene in a conventional [3+2] dipolar cycloaddition. Two distinct, but similar, reaction mechanisms were found †an asymmetric concerted pathway and a stepwise zwitterionic pathway. The reaction barriers of the two pathways were nearly identical, differing by less than ~1 kcal/mol, no matter what the substituents were. The effect of a Lewis acid catalyst was examined and found to have a very large effect on the calculated barriers through coordination to the carbonyl oxygen atoms of the diester substituents on the cyclopropane. The reaction barrier was found to decrease by as much as ~19 ...
If you have a question about this talk, please contact .. The development of bioorthogonal reactions made it possible to visualize and study biomolecules in their native cellular context and contributed to advanced targeted drug delivery strategies. In our research group we are interested in developing novel bioorthogonal chemistry and apply this in the targeting of specific cell types. We recently added non-strained, highly soluble and stable vinylboronic acids (VBA) as reactants to the bioorthogonal toolbox which react with tetrazines in an inverse-electron demand Diels-Alder reaction. We have observed exceptional high reaction rates between non-strained vinylboronic acids (VBAs) and dipyridyl tetrazines relative to that of tetrazines lacking such dative coordinating ligand. As VBAs are mild Lewis acids, we hypothesize that coordination of the pyridyl to the boronic acid promotes the tetrazine ligation. In the current presentation, we explore the scope and molecular origins of the observed VBA ...
Abstract: The mechanisms of cycloaddition reactions of singlet dibromocarbene and formaldehyde have been studied using density functional theory of quantum chemistry method at B3LYP/6-31G* level. The geometrical parameters, harmonic vibrational frequencies and energies of stationary points on the potential energy surface are calculated. The structures of the stationary points were optimized, and the intermediates and transition states were detected by the frequency analysis. The calculation results show that the reaction has four possible reaction pathways. According to the data of the activation energy, we predict that path c would be the major reactive channel of the cycloaddition reactions of singlet dibromocarbene with formaldehyde, which proceeds in three steps and the energy barrier for the key step is 13.7 kJ·mol-1. Key words: Density functional theory, Cycloaddition reaction, Transition states, Dibromocabene, B3LYP level ...
Taking the 266 nm excited pyrimidine (uracil or thymine) with cyclopentene as model reaction systems, we have examined the photoproduct formation dynamics from the [2 + 2] photocycloaddition reactions of triplet pyrimidines in solution and provided mechanistic insights into this important DNA photodamage reaction. By combining two compliment methods of nanosecond time-resolved transient IR and UV-vis laser flash-photolysis spectroscopy, the photoproduct formation dynamics as well as the triplet quenching kinetics are measured. Characteristic IR absorption bands due to photoproduct formation have been observed and product quantum yields are determined to be similar to 0.91% for uracil and similar to 0.41% for thymine. Compared to the measured large quenching rate constants of triplet uracil (1.5 x 10(9) M(-1)s(-1)) or thymine (0.6 x 10(9) M(-1)s(-1)) by cyclopentene, the inefficiency in formation of photoproducts indicates competitive physical quenching processes may exist on the route leading to ...
Lawrence Scott and Marina Petrukhina discuss their new book on fullerene fragments and other open geodesic polyaromatic molecules .
A stereoselective total synthesis of (+)-$\alpha$-herbertenol starting from the allyl alcohol 12, readily available in three steps from the monoterpene (R)-limonene, is described. Claisen rearrangement of the aryl allyl ether 10 and concomitant cyclisation furnished a 5:3 mixture of the tricyclic compounds 13 and 14. Degradation of the isopropenyl group followed by cleavage of the central ring and functional group manipulation transformed 13 into (+)-$\alpha$-herbertenol (1b).. ...
TY - JOUR. T1 - Synthesis, spectroscopy, and applications of small nitrile oxides. AU - Pasinszki, Tibor. AU - Westwood, Nicholas P.C.. PY - 2011/6. Y1 - 2011/6. N2 - Small covalent nitrile oxides are important transient species in organic synthesis and widely used especially for dipolar cycloaddition reactions. Due to their instability, their isolation and characterization are challenging. This review focuses on the generation, spectroscopy, structural properties, and synthetic application of small nitrile oxides, XCNO, where the X substituent group is smaller than five atoms, viz. X= hydrogen, halogen, pseudohalogen, alkyl, vinyl, ethynyl, or nitro.. AB - Small covalent nitrile oxides are important transient species in organic synthesis and widely used especially for dipolar cycloaddition reactions. Due to their instability, their isolation and characterization are challenging. This review focuses on the generation, spectroscopy, structural properties, and synthetic application of small ...
In 1908, Ciamician discovered that upon exposure of carvone to sunlight for one year, carvone camphor resulted.[2] After this finding was confirmed in the 1950s, a flurry of research identified the synthetic value of the photochemical [2+2] cycloaddition between enones and alkenes for the construction of complex molecular frameworks.[3][4] In spite of the stepwise, radical mechanism, both stereoselective intra- and intermolecular variants have emerged. Cyclic enones must be used to prevent competitive cis-trans isomerization. [2+2] Photocyclization may produce two constitutional isomers, depending on the orientation of substituents on the alkene and the enone carbonyl group. When the enone carbonyl and substituent of highest priority are proximal, the isomer is termed head-to-head. When the enone carbonyl and substituent are distal, the isomer is called head-to-tail. Selectivity for one of these isomers depends on both steric and electronic factors (see below). (1) ...
Green Chem., 2013, 15,2384-2388 DOI: 10.1039/C3GC41126E, Communication Dwun Kit Jonathan Yeung,a Tao Gao,b Jiayao Huang,a Shaofa Sun,b Haibing Guob and Jian Wang*a * Corresponding authors a Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore E-mail: [email protected] ; Fax: (+)65-6516-1691 b HuBei Collaborative Innovation Center of Non-power Nuclear Technology, Hubei University of Science and Technology, Hubei Province, China Received 12 Jun…
Intramolecular transannular dipolar cycloaddition was investigated as a key step in a synthetic approach to the core of the sarain alkaloids; although the use of an azomethine ylide was unsuccessful with the chosen aldehyde substrate, cycloaddition with a nitrone did give the alternative regioisomeric bridge
A new method of adding fluorescent labels to the middle of oligonucleotides is reported. Diets-Alder cycloaddition was used to add five fluorescent maleimides to an oligonucleotide containing a 2-deoxyuridine modified at the 5-position with a spaced furan. This is a new approach to internal oligonucleotide chemistry that opens Lip a large range of possibilities for further conjugation.. ...
TY - JOUR. T1 - The retro Diels-Alder reaction as a valuable tool for the synthesis of heterocycles. AU - Stájer, Géza. AU - Csende, Ferenc. AU - Fülöp, Ferenc. PY - 2003/9/1. Y1 - 2003/9/1. N2 - Applications of the retro Diels-Alder reaction (cycloreversion) under mild conditions for the laboratory preparation of heteromonocycles or condensed-ring heterocycles are reviewed. A new method utilizes diendo- or diexo-3-aminonorbornene-2-carboxylic acids and their derivatives for the formation of heterocyclic ring systems which are difficult to access by other routes or which can be prepared only in complicated multi-step procedures. The synthesis of substituted 1,3-dienes (e.g. furan derivatives) and O,N- or N,N-heterocycles (oxazoles, isoxazoles, pyrazoles, imidazoles, triazoles, pyrimidinones, oxazinones, pyridazinones etc) are discussed.. AB - Applications of the retro Diels-Alder reaction (cycloreversion) under mild conditions for the laboratory preparation of heteromonocycles or ...
Medvedev, et al. have examined the cyclization step in the formation of Spinosyn A, which is catalyzed by the putative Diels-Alderase enzyme SpnF.1 This work follows on the computational study done by Houk, Singleton and co-workers,2 which I have discussed in this post (Dynamics in a reaction where a [6+4] and [4+2] cycloadditons compete). In fact, I recommend that you read the previous post before continuing on with this one. In summary, Houk, et al. found that a single transition state connects reactant 1 to both 2 and 3. The experimental product with the enzyme SpnF is 3. In the absence of enzyme, Houk, et al. suggest that reactions will cross the bispericyclic transition state TS-BPC (TS1 in the previous post) leading primarily to 2, which then undergoes a Cope rearrangement to get to product 3. Some molecules will follow pathways that go directly to 3 ...
A hexafullereno-diporphyrinoid was obtained in a sequence of cycloaddition steps using porphyrins programmed for [4+2]-cycloaddition reactions and C60-fullerene. Porphyrins & Phthalocyanines
PENTALENIC ACID; (2-CHLOROETHYL)NITROSOUREAS; 1,3-DICARBONYL COMPOUNDS; 1,4-DIAZABICYCLO<2.2.2>OCTANE; 2+2 PHOTOCYCLOADDITION; 2-CYCLOHEXENONE; 2-PYRIDINONE DERIVATIVES; 3-METHYLADENINE DNA GLYCOSYLASE; 4-HYDROXYCINNAMAMIDE DERIVATIVES; 5-FLUOROURACIL; 9-ALKOXYPURINES; ABSORPTION; ACID DERIVATIVES; ACYCLIC NUCLEOSIDES; AGENTS; ALKYLATING-AGENTS; ALKYLTRANSFERASE; ALPHA,BETA-UNSATURATED KETONES; AMIDE CONFORMERS; ANALOGS; ATASE; BREAST; CALCIUM-CHANNEL; CELL-LINES; CHLOROETHYLNITROSOUREA; CLEAVAGE; COLON; CROSS-LINK; DACARBAZINE; DERIVATIVES; DNA-DAMAGE; DOUBLE MICHAEL REACTION; ETHERS; FACILE; HERPES-SIMPLEX VIRUS; HETEROCYCLIC ENAMINES; HUMAN-TUMOR-CELLS; HYPOIODITE; INACTIVATION; INHIBITORS; ISOMERS; LUNG-TUMORS; MALIGNANT-MELANOMA; MALONONITRILE; MAMMALIAN O-6-ALKYLGUANINE-DNA ALKYLTRANSFERASE; MECHANISM; METHYLATING AGENTS; METHYLENE-COMPOUNDS; MGMT; MICE; MOLECULES; N-ISOPROPYLIDENEHYDRAZINOCARBONYL DERIVATIVES; NITROSOUREA; NMR; NUCLEAR MAGNETIC-RESONANCE; O-6-METHYLGUANINE; ...
Cathodic reduction of the nitro moiety and subsequent intramolecular cyclization affords different substituted 2,1-benzisoxazoles and quinoline N-oxides.
Sonification of N-benzyl-N-(methoxymethyl)-N-[(trimethylsilyl)methyl]amine (5a) in the presence of LiF led to the formation of the reactive azomethine ylide 1d, which was intercepted by cyclic thioketones to give spirocyclic 1,3-thiazolidines. In the case of 2,2,4,4-tetramethylcyclobutane-1,3-dithione, the 1:1- and 1:2-cycloadduct, respectively, was formed as the major product depending on the ratio of the starting materials. With 1,3-thiazole-5(4H)-thiones, 1d undergoes stereoselective [2+3]-cycloadditions with the C=S group to yield spirocyclic 1:1-adducts. In the case of the 1,3-dipole generated from N-benzyl-N-(methoxymethyl)-N-[1-(trimethylsilyl)ethyl]amine (5b), the [2+3]-cycloaddition proceeded in a non-regioselective manner leading to a mixture of regio- and diastereoisomers. ...
Organic chemists have long recognized the important role that reaction media play in controlling rates, product distributions and stereochemistry. Recently, much effort has been directed towards the use of organized media to modify reaftivity as compared to that in isotropic liquids. Judicious selection of a given organized system for a given application requires sufficient understanding of the properties of the organized media themselves and those of the substrate interactions therein. The multimolecular aggregation of hydrophobic solutes in water could prove to be of immense value to the organic chemist. The aggregation of simple olefinic systems in water would enable photocycloaddition to compete efficiently with the various other modes of dacay of the short-lived excited state. Investigations of a few systems (dimerization of coumarins, stilbenes and alkylcinnamates) in our laboratory have been successful and they bring to light the significance of the hydrophobic effect. One of the most ...
The title compound, N,N-dibenzyl-1-(1-[(4-methyl-2-phenyl-4,5-dihydrooxazol-4-yl)methyl)]-1H-1,2,3-triazol-4-yl)methanamine was synthesized in high yield by 1,3-dipolar cycloaddition reaction of 4-(azidomethyl)-4-methyl-2-phenyl-4,5-dihydrooxazole and N,N-dibenzylprop-2-yn-1-amine in toluene at reflux. The structure of this product was established on the basis of NMR spectroscopy (1H, 13C), Elemental Analysis and MS data.
Vishwakarma Singh and co-workers from IIT Bombay have published in Organic and Biomolecular Chemistry on an oxidation of a phenol that yields a Diels-Alder substrate that dimerizes on itself and when the dimer is heated reforms the dienone substrate that undergoes an intramolecular Diels-Alder reaction. So the sequence goes like so: intermolecular Diels-Alder to retro-Diels-Alder…
Almost all successful syntheses of bicyclic beta-lactams involve the early synthesis of the monocyclic azetidin-2-one ring. Of the numerous methods developed to achieve this, the [2+2] cycloaddition of chlorosulphonyl isocyanate (CSI) to functionalised alkenes has proven to be particularly useful. In general, addition is performed on alkenyl acetates providing C-4 acetoxyazetidinones, which have found widespread use since the 4-acetoxy substituent can be replaced with various nucleophiles in an elimination/addition sequence. However, there are few functionalised alkenes which directly introduce the C-4 carbon substitution required for carbapenem synthesis upon cycloaddition with CSI. Earlier investigations within this group have shown that allylsilanes undergo regioselective cycloaddition with CSI to yield C-4 silylmethyl substituted beta-lactams.133,137 The regiochemistry of cycloaddition is controlled by the beta-effect of silicon, i.e., silicons ability to stabilise the development of ...
B. R. Buckley and H. Heaney: Mechanistic Investigations of Copper(I)- Catalyzed Alkyne-Azide Cycloaddition Reactions.- J. D. Crowley and D. A. McMorran:
The intermediate [Zn(4-PTZ)2(H2O)4] (4-PTZ=5-(4-pyridyl N-oxide)tetrazolate) (1) in the synthesis of 4-H-PTZ (2) from cycloaddition reaction of 4-cyanopyridine N-oxide with NaN3 in water catalyzed by ZnCl2 was structurally characterized. The catalysis role of Zn2+ in the synthesis of tetrazole stems from the formation of tetrazolate zinc complex 1. © 2004 Elsevier B.V. All rights reserved ...
Rh-Catalyzed [5+1] and [4+1] Cycloaddition Reactions of 1,4 Enyne Esters with CO : A Shortcut to Functionalized Resorcinols and Cyclopentenones ...
We systematically studied the heats of formation (HOFs) for a series of 3,3′-azobis-1,2,4, 5-tetrazine derivatives by den... ...
Sydnone based cycloaddition reactions are a versatile platform for pyrazole synthesis, however they operate under harsh conditions (high temperature and long reaction times). Herein we report a strategy that addresses this limitation utilizing the synergistic combination of organocatalysis and visible light photocatalysis. This new approach proceeds under ambient conditions and with excellent levels of regiocontrol. Mechanistic studies suggest that photoactivation of sydnones, rather than enamines, is key to the successful implementation of this process.. ...
It seemed plausible that the biosynthesis of Bistellettadine A (9) was proceeding by intermolecular dimerization of the monomeric carboxylic acid corresponding to 7. Barry B. Snider of Brandeis University found (Org. Lett. 2010, 12, 828. ) that that intermolecular dimerization did proceed efficiently, but to give a 5:4 mixture of diastereomers. In contrast, the linked diester 7 cyclized with exclusive diastereocontrol. The product 8 was readily carried on to Bistellettadine A 9. This raises the possibility that a chiral template, attached either covalently or through salt formation, could be designed that would direct the absolute configuration of the cycloaddition.. ...
The (3+2)-cycloaddition reaction involving oxyallyl cations has proven to be a versatile and efficient approach for the construction of five-membered carbo- and heterocycles, which are prevalent frameworks in natural products and pharmaceuticals. The following article will provide a brief summary of recent disclosures on this process featuring chemo-, regio- and diastereoselective oxyallyl cycloadditions with both electron-rich and electron-deficient 2π partners.
Intermolecular asymmetric 1,3-dipolar cycloaddition of 2,2-dimethyl-3,4-dihydro-2H- pyrrole N-oxide and N-(benzylidene)methylamine N-oxide with optically active α, β-unsaturated esters 1,2,4 and 7-9 provided the corresponding diastereomers while chiral sugar lactones gave stereoselectively the cycloadducts 17a and 17b (in the case of dipolarophile 3) and 18 in (the case of the dipolarophile 6) with the acyclic nitrone B. The stereochemistry of the products has been established using high field nmr techniques. The regioselectivities of these reactions are inconsistent with FMO coefficients and are explained on the basis of charge distribution obtained through AM1 calculations. ...
This video was recorded at CHEM 125b: Freshman Organic Chemistry II. Cyclic conjugation that arises when p-orbitals touch one another can be as important for transition states as aromaticity is for stable molecules. It is the controlling factor in pericyclic reactions. Regiochemistry, stereochemistry, and kinetics show that two new sigma bonds are being formed simultaneously, if not symmetrically, in the 6-electron Diels-Alder cycloaddition. Although thermal dimerization of thymine residues in DNA is forbidden, photochemistry allows the 4-electron cycloaddition. Electrocyclic ring opening or closing chooses a conrotatory Möbius pathway, or a disrotatory Hückel pathway, according to the number of electron pairs involved and whether light is used in the process. Dewar benzene provides an example of a very unstable molecule that can be formed photochemically and then persists because of unfavorable orbital overlap in the transition state for ring opening ...
TY - JOUR. T1 - Intramolecular nitrile oxide-alkene cycloaddition of sugar derivatives with unmasked hydroxyl group(s). AU - Shing, Tony Kung Ming. AU - Wong, Wai F.. AU - Cheng, Hau M.. AU - Kwok, Wun S.. AU - So, King H.. PY - 2007/3/1. Y1 - 2007/3/1. N2 - (Chemical Equation Presented) Intramolecular nitrile oxide-alkene cycloaddition (INOC) of sugar derivatives with one to four free hydroxyl group(s) is reported. The INOC reaction, using chloramine-T, in the presence of silica gel, to generate nitrile oxides from oximes, proceeded smoothly to afford five- or six-membered carbocycles in good to excellent yields. This new methodology alleviates protection/deprotection steps and makes the synthetic route shorter and more efficient.. AB - (Chemical Equation Presented) Intramolecular nitrile oxide-alkene cycloaddition (INOC) of sugar derivatives with one to four free hydroxyl group(s) is reported. The INOC reaction, using chloramine-T, in the presence of silica gel, to generate nitrile oxides from ...
The Diels-Alder reaction is one of the most powerful synthetic tools in organic chemistry, and asymmetric Diels-Alder catalysis allows for rapid construction of chiral carbon scaffolds. For this reason, considerable effort has been invested in developing efficient and stereoselective organo- and biocatalysts. However, Diels-Alder is a virtually unknown reaction in Nature, and to engineer an enzyme into a Diels-Alderase is therefore a challenging task. Despite several successful designs of catalytic antibodies since the 1980s, their catalytic activities have remained low, and no true artificial Diels-Alderase enzyme was reported before 2010.. In this thesis, we employ state-of-the-art computational tools to study the mechanism of organocatalyzed Diels-Alder in detail, and to redesign existing enzymes into intermolecular Diels-Alder catalysts. Papers I-IV explore the mechanistic variations when employing increasingly activated reactants and the effect of catalysis. In particular, the ...
A series of novel purine-based fluoroaryl triazoles were synthesized using the Cu(I) catalyzed 1,3-dipolar cycloaddition reactions (click reactions), and assayed for their neuroprotective effects using fluorescence electron microscopy. Among these triazoles, o-fluorophenylmetyl-triazole, 7, has comparable neuroprotective effect as that of Flavopiridol (1) and Roscovitine (2), the state of the art CDK inhibitors, against the Aß induced neurotoxicity. These results are substantiated using computer docking methods (DarwinDock/GenDock), which predict that Roscovitine and the triazole 7 bind to the ATP-binding site of CDK5/p25 with comparable binding energies, whereas the corresponding pentafluorophenylmethyl-triazole, 9, has dramatically reduced binding energy (in accordance with its lack of neuroprotection). These combined experimental and theoretical studies support the involvement of CDK5/p25 in the neuronal cell cycle re-entry.
In the structures a, b and c the first two are dipolar (1,2-dipoles; curiously, no actual 1,3 dipoles make it since they apparently do not contribute significantly) and c is neutral. There is no mention (I might have missed it) in the quoted article about the individual contributions of the three structures to the overall dipole moment. My experience is that once a dipole moment reaches about 6D, solvation of that state starts having a very significant impact on its energy, indeed its geometry (even if the solvent is merely a typical organic solvent such as dichloromethane). In a recent study which will be published shortly, we compared two ion pairs in the isobornyl chloride system. In the gas phase, one ion pair had a dipole moment of ~32D (!), and this was a great deal higher (~20 kcal or more) than another in energy with a dipole moment of only 14D. But once solvation is applied, the two become equal in energy. Geometry re-optimization was critical. OK, these are extreme dipoles, and the ...
Green chemistry brings an attention on a research work emerging from scientific innovations regarding toxic waste acquaintance and it make the use of ..
To quote Yogi Berra, Deja Vu all over again! This was a hot topic in the 1970s, but then the debate was whether semi-empirical methods could handle this hot potato. I think we can say the DFT methods eventually won that one. But in 1991, I note we too were fretting on the theme of Transition state structure in cycloaddition reactions as a function of ring size and geometry, namely how many electrons could be involved in a pericyclic reaction before it turns stepwise? We decided then the transition (for a neutral hydrocarbon it has to be said) was somewhere between 10 and 14. I think that may well still be the modern view. For systems where zwitterions are more heavily stabilized, it is no surprise that it comes earlier. I do note that although the bibliography in Fernandez, Sierra and Torres article is extensive, it does not cite our article. A related question might be whether these higher electron systems (4n+2, n=2,3) might ever sustain Möbius topologies. Thus again for a hydrocarbon (DOI: ...
Angewandte Chemie DOI: 10.1002/ange.200903427 Strained Molecules Foregoing Rigidity to Achieve Greater Intimacy** Alexander S. Filatov, Edward A. Jackson, Lawrence T. Scott, and Marina A. Petrukhina* Interactions between the surfaces of planar and nonplanar molecules have generated considerable interest in materials chemistry[1, 2] as critical elements for understanding twodimensional supramolecular assembly, molecular and chiral recognition, and heterogeneous catalysis. Carbon-rich balland bowl-shaped polyaromatic molecules, such as fullerenes and fullerene fragments or buckybowls, figure prominently in these studies. Fullerenes have been found to form solid constructs with planar metalloporphyrins with remarkably close contacts but without the need for matching their convex and concave faces.[3] Molecular self-organization of nonplanar polyaromatic bowls on a planar metal surface introduces the interesting additional factor of symmetry mismatch.[4] Studies of ordered structures formed by ...
The 1,3-dipolar cycloaddition of acyclic 2-diazo-1,3-dicarbonyl compounds (DDC) and thioketones preferably occurs with Z,Econformers and leads to the formation of transient thiocarbonyl ylides in two stages. The thermodynamically favorable further transformation of C=S ylides bearing at least one acyl group is identified as the 1,5-electrocyclization into 1,3-oxathioles. However, in the case of diazomalonates, the dominating process is 1,3-cyclization into thiiranes followed by their spontaneous desulfurization yielding the corresponding alkenes. Finally, carbocyclic diazodiketones are much less reactive under similar conditions due to the locked cyclic structure and are unfavorable for the 1,3-dipolar cycloaddition due to the Z,Z-conformation of the diazo molecule. This structure results in high, positive values of the Gibbs free energy change for the first stage of the cycloaddition process ...
A three-component reaction of an alpha ,alpha -disubstituted alpha -isocyanoacetamide, an aldehyde and an amino alc. afforded 5-iminooxazolines, which, upon sapon., cyclized under acidic conditions to provide the macrocyclodepsipeptides in good overall yields. [on SciFinder (R)]. Keywords: Alcohols Role: RCT (Reactant) ; RACT (Reactant or reagent) (amino; prepn. of iminooxazolines via ammonium chloride-promoted three-component reaction of isocyanoacetamides ; aldehydes and amino alcs.); Peptides Role: SPN (Synthetic preparation) ; PREP (Preparation) (depsipeptides ; macrocyclic; prepn. of macrocyclodepsipeptides via cyclization of iminooxazolines); Aldehydes Role: RCT (Reactant) ; RACT (Reactant or reagent) (prepn. of iminooxazolines via ammonium chloride-promoted three-component reaction of isocyanoacetamides ; aldehydes and amino alcs.); Ugi reaction (prepn. of isocyanoacetamides via Ugi reaction of ketones ; ammonium formate and isocyanoacetates); Ketones Role: RCT (Reactant) ; RACT (Reactant ...
Abstract. An efficient chiral Lewis acid-catalyzed inverse-electron-demand Diels-Alder reaction of N-sulfonyl 1-aza-1,3-dienes is based on the combination of Ni(II)-DBFOX complex as catalyst and the use of a metal-coordinating (8-quinolyl)sulfonyl moiety. The reaction provides highly functionalized piperidine derivatives in good yields with excellent endo-selectivity, and good enantioselectivities.. ...
The central themes of our research program are the development of methodology to accomplish the synthesis of optically pure materials and the subsequent application of the new methodology to the total synthesis of biologically significant natural products. At the present time there are several different approaches to a variety of targets in progress in our laboratories. The first is the transfer of chirality from optically active hydroxylamines (e.g.,1) employing intra-and intermolecular nitrone /alkene cycloaddition reactions in the chirality transfer step. Particular targets for this chemistry are several unusual alpha-amino acids (2) as well as alkaloids related to pretazettine (3). The synthesis of pretazettine is also being addressed in a different approach involving a chiral ring expansion of allylic alcohol (4). Recently, significant progress has been realized in the synthesis the alkaloid gelsemicine (7) based on the Diels-Alder reaction of chiral maleimides such as (5). It has been ...
The central themes of our research program are the development of methodology to accomplish the synthesis of optically pure materials and the subsequent application of the new methodology to the total synthesis of biologically significant natural products. At the present time there are several different approaches to a variety of targets in progress in our laboratories. The first is the transfer of chirality from optically active hydroxylamines (e.g.,1) employing intra-and intermolecular nitrone /alkene cycloaddition reactions in the chirality transfer step. Particular targets for this chemistry are several unusual alpha-amino acids (2) as well as alkaloids related to pretazettine (3). The synthesis of pretazettine is also being addressed in a different approach involving a chiral ring expansion of allylic alcohol (4). Recently, significant progress has been realized in the synthesis the alkaloid gelsemicine (7) based on the Diels-Alder reaction of chiral maleimides such as (5). It has been ...
3,6-Bis(2,4-dimethyl-1H-pyrrol-1-yl)-1,2,4,5-tetrazine/ACM30169256 can be provided in Alfa Chemistry. We are dedicated to provide our customers the best products and services.
Cycloadditionsreaktionen von Heterokumulenen, IX. 1:1-, 2:1- und 3:1-Addukte aus der Umsetzung von Isothiocyanaten mit 3-Dimethylamino-2,2-dimethyl-2H-azirin (Cycloaddition reactions of heterocumulenes, IX. 1:1-, 2:1-, and 3:1-Adducts from the reaction of isothiocyanates with 3-dimethylamino-2,2-dimethyl-2H-azirine) ...
Gilvocarcin V (GV) and ravidomycin (RMV) exhibit excellent antitumor activities in the presence of near-UV light at low concentration maintaining a low in vivo cytotoxicity. Although, the exact molecular mechanism for in vivo actions of these antibiotics has yet to be determined, a [2+2] cycloaddition reaction of the vinyl side chain with DNA thymidine residues in addition to the inhibition of topoisomerase II and DNAhistone H3 cross-linking are reported for the GVs mechanism of action. Such activities have made these molecules interesting candidates for the biosynthetic investigation to generate analogues with improved activity/solubility. Previous biosynthetic studies have suggested that the GV biosynthetic pathway involves a number of synchronously occurring transformations leading to the oxidative C-C bond cleavage and other intriguing biosynthetic reactions, such as the vinyl side chain formation, methylations, Cglycosylation and dehydrogenation. Although gene inactivation results identified many
One-pot synthesis of 3-vinyl substituted indoles containing 1,2-amino alcohol fragment at the nitrogen atom was performed by the reactions of 1-(oxiran-2-y
In this study we describe the development and validation of a highly miniaturized screening platform for the identification of novel protein interactors of both proteins and small molecules using MAPPIT and MASPIT. Even though these are mammalian cell-based assays, which are typically less amenable to high-throughput applications than most in vitro or Y2H assays, the approach allows testing thousands of target proteins in parallel, with short overall timelines and requiring little hands-on time. Despite the high density of the arrays, signals are robust and reproducible, resulting in a reliable primary screening output and high confirmation rates. The identification of previously described interacting proteins and the confirmation of selected interactions with orthogonal methods validated the screening results.. The different applications described here illustrate the versatility of the screening platform. The interactome of a designated protein of interest can be determined efficiently, as such ...
The development of RGD-based antagonist of αvβ3 integrin receptor has enhanced the interest in PET probes to image this receptor for the early detection of cancer, to monitor the disease progression and the response to therapy. In this work, a novel prosthetic group (N-(4-fluorophenyl)pent-4-ynamide or FPPA) for the (18)F-labeling of an αvβ3 selective RGD-peptide was successfully prepared. [(18)F]FPPA was obtained in three steps with a radiochemical yield of 44% (decay corrected). Conjugation to c(RGDfK(N3)) by the Cu(II) catalyzed Huisgen azido alkyne cycloaddition provided the [(18)F]FPPA-c(RGDfK) with a radiochemical yield of 29% (decay corrected), in an overall synthesis time of 140 min ...
Kendall Houk and co-workers have reported in JACS on a biosynthetic study of heronamide A using DFT calculations to study the [6+4] cycloaddition. JACS paper
Monty Liong is the author of this article in the Journal of Visualized Experiments: Reversibly छोटे अणुओं या Biosensor अनुप्रयोगों के लिए बहु घटक संरचनाएं स्थिर microfluidic पर चिप कब्जा cycloaddition के रिएक्शन
Get this from a library! Bioconjugation protocols : strategies and methods.. [Sonny S Mark; Christof M Niemeyer] -- Contemporary approaches to the synthesis of chemically modified biomacromolecules (proteins, nucleic acids, lipids, and carbohydrates) not only require efficient means to control conjugation and the ...
An alkyne trimerisation reaction is a [2+2+2] cycloaddition reaction in which three alkyne units react to form a benzene ring. ... Being a cycloaddition reaction, it has high atom economy. Many variations have been developed including cyclisation of mixtures ... Wills, M. S. B.; Danheiser, R. L. (1998). "Intramolecular [4 + 2] Cycloaddition Reactions of Conjugated Ynones. Formation of ... The reaction requires a metal catalyst. The process is of historic interest as well as being applicable to organic synthesis. ...
The reaction centers around an imine - lithium enolate cycloaddition. In order to ensure the correct stereochemistry (the ... Both imine and enole intermediate join in a cycloaddition reaction followed by an intramolecular nucleophilic acyl substitution ... Reaction with phenyllithium affords the enolate. The imine synthesis is a reaction of hexamethylene silazane with phenyllithium ... The hydroxyl group is protected by a benzyl group and the carboxylic acid is activated by reaction with thionyl chloride to the ...
... is reactive in cycloaddition reactions. Norbornadiene is also the starting material for the synthesis of ... Norbornadiene is also a useful dienophile in Diels-Alder reactions. Norbornadiene can be formed by a Diels-Alder reaction ... Quadricyclane, a valence isomer, can be obtained from norbornadiene by a photochemical reaction when assisted by a sensitizer ... in reactions with phosphine ligands. Norbornane a saturated compound with the same carbon skeleton. Norbornene a compound with ...
Evans, D. A.; Chapman, K. T.; Bisaha, J. (1984). "New Asymmetric Diels-Alder Cycloaddition Reactions. Chiral α,β-Unsaturated ... including aldol reactions, alkylation reactions, and Diels-Alder reactions. The oxazolidinones are substituted at the 4 and 5 ... utilizes oxazolidinone chiral auxiliaries for one asymmetric alkylation reaction and four asymmetric aldol reactions, setting ... The cycloaddition product was carried forward to the iodolactone shown below, an intermediate in the classic Corey synthesis of ...
3-dipolar cycloaddition reaction. These compounds may be protonated by strong acids to give synthetically useful aromatic ... 1,4,2-Dithiazole compounds may be formed by the reaction of nitrile sulfide (formed by the thermolysis of oxathiazolone) with ... Part 3. Preparation of 5H-1,4,2-dithiazoles via 1,3-dipolar cycloadditions between nitrile sulphides and thiocarbonyl compounds ... and some novel reactions". Journal of the Chemical Society, Perkin Transactions 1 (16): 2065. doi:10.1039/p19920002065. ISSN ...
3-dipolar cycloaddition reaction". Tetrahedron Letters. 27 (27): 3181-3182. doi:10.1016/S0040-4039(00)84748-6. Bowden, K.; ... Muscimol was synthesized in 1965 by Gagneux, who utilized a bromo-isoxazole starting material in a two step reaction. 3-bromo-5 ...
Specifically, Sulfur dioxide participates in cycloaddition reactions with dienes. The industrially useful solvent sulfolane is ... In the Ramberg-Bäcklund reaction and the Julia olefination, sulfones are converted to alkenes by the elimination of sulfur ... Sulfones are prepared under conditions used for Friedel-Crafts reactions using sources of RSO+ 2 derived from sulfonyl halides ... Truce, W. E.; Vriesen; C. W. (1953). "Friedel-Crafts Reactions of Methanesulfonyl Chloride with Benzene and Certain Substituted ...
Liu, Lei; Montgomery, John (2007-09-01). "[3+2] Cycloaddition Reactions of Cyclopropyl Imines with Enones". Organic Letters. 9 ... Tamaki, Takashi; Ohashi, Masato; Ogoshi, Sensuke (2011-12-09). "[3+2] Cycloaddition Reaction of Cyclopropyl Ketones with ... Examples of intramolecular reactions with a tethered alkyne and intermolecular reactions with a nontethered alkyne both exist ... The resulting metallacycles are susceptible to a variety of reactions. These reactions are rare examples of C-C bond activation ...
... also participates in [4+2] cycloaddition reactions. Its reaction with acrolein is the first step in the ... Methyl vinyl ether can be made by reaction of acetylene and methanol in presence of a base. The alkene portion of the molecule ... 1-dimethoxyethane by the catalysed reaction of acetylene with methanol". Catalysis Today. 145 (1-2): 163-168. doi:10.1016/j. ...
... cycloaddition reactions between metal fluorocarbenes and tetrafuoroethylene (TFE), which sheds light on a greener route to ... Cycloaddition Reactions with Tetrafluoroethylene and Reactivity of the Perfluorometallacyclic Products". Journal of the ... "Reactions of catecholborane with Wilkinson's catalyst: implications for transition metal-catalyzed hydroborations of alkenes". ... work provides insight into the second hydrogen release step of dehydrogenation by isolation and characterization of reaction ...
... cycloaddition reactions. Additional evidence for the existence of benzyne came from spectroscopic studies. Benzyne has been ... Generation of the benzyne intermediate is the slow step in the reaction. "Aryne coupling" reactions allow for generation of ... A hexadehydro Diels-Alder reaction (HDDA) involves cycloaddition of 1,3-diyne and alkyne. N-amination of 1H-benzotriazole with ... showed that the reaction of chlorobenzene-1-14C and potassium amide gave equal amounts of aniline with 14C incorporation at C-1 ...
Only the C2-C3 pi bond of indole is capable of cycloaddition reactions. Intramolecular variants are often higher-yielding than ... Indoles also undergo intramolecular [2+3] and [2+2] cycloadditions. Despite mediocre yields, intermolecular cycloadditions of ... intermolecular cycloadditions. For example, Padwa et al. have developed this Diels-Alder reaction to form advanced strychnine ... Reaction of N-protected indoles with butyl lithium or lithium diisopropylamide results in lithiation exclusively at the C2 ...
It is a component in cycloaddition reactions that produce substituted azides and isoindolinones.[better source needed] 2-Hexyne ... Hogsed, M. J.; Lindsey, R. V. (1953-10-01). "The Reaction of 1-Hexyne and Diethyl Fumarate". Journal of the American Chemical ...
The azide alkyne Huisgen cycloaddition is a mild and selective reaction that gives 1,2,3-triazoles as products. The reaction ...
Although stannylenes are more stable than its lighter carbene analogs, they readily undergo [2+4] cycloaddition reaction with Z ... The reaction between stannylene and 9,10-phenanthrolinedione produces an EPR signal that was identified to be 9,10- ... Eaborn, Colin; Smith, J. David (2002). "Reactions of a Highly Crowded Cyclic Stannylene with Iodoalkanes, Enones, and Dienes. ... Neumann, Wilhelm P. (1984). "[2+4] Cheletropic cycloaddition of stannylenes R2Sn". Tetrahedron Lett. 25 (6): 625-628. Wang, ...
In organic synthesis, vinyl oxocarbenium ions (structure on right) can be utilized in a wide range of cycloaddition reactions. ... Harmata, M.; Rashatasakhon, P. (2003), "Cycloaddition reactions of vinyl oxocarbenium ions", Tetrahedron, 59 (14): 2371-2395, ... In organic reactions, ketones are commonly activated by the coordination of a Lewis acid or Brønsted acid to the oxygen to ... "Stereochemical Reversal of Nucleophilic Substitution Reactions Depending upon Substituent: Reactions of Heteroatom-Substituted ...
It finds many uses in organic reactions such as the CBS reduction, Diels-Alder reactions and (3+2) cycloadditions. Proline, a ... Proline derivative 3d is prepared in a separate leg from a Grignard reaction with Grignard reagent 3c and proline ester 3b. A ... The first leg of the reaction sequence starts from the azeotropic dehydration of a boronic acid (1) such as one based on ... It transfers its stereocenter to the catalyst which in turn is able to drive an organic reaction enantioselectively to one of ...
Through a cycloaddition reaction involving both of the functional groups and manipulation of the solvent pH, diblock and star ... This amplification is due to the fact that the initial segment added to the reaction functions as a template, from which ... ELPs can be experimentally modified through conjugation with other polymers or through SpyTag/SpyCatcher reaction, allowing for ... overlap extension polymerase chain reaction (OEPCR), and recursive directional ligation (RDL). Also, ...
AKD's react with the hydroxyl groups on the cellulose via esterification reaction. They will also undergo [2+2] cycloaddition ... Other ketenes can be prepared from acyl chlorides by an elimination reaction in which HCl is lost: In this reaction, a base, ... 410-412, ISBN 3871449024 Jie Jack Li (2006), Name reactions. A collection of detailed reaction mechanisms (in German) (3 ed.), ... cycloaddition. The example shows the synthesis of a β-lactam by the reaction of a ketene with an imine (see Staudinger ...
"Quantifying Asymmetry in Concerted Reactions: Solvents Effect on a Diels-Alder Cycloaddition", J. Org. Chem., 76, 4973 - 4979 ( ... This early work focused on the origin of patterns and structures which form as a result of reactions that solutions of ... dissipative structures - this is how such structures are called - were found for a wide array of different reactions. Kaye ... metal hybrids in a one-pot multistep opposing oxidation and reduction reactions-sequence", ChemCatChem, 9, 816 - 823 (2017). ...
Cycloadditions[edit]. Cycloaddition reaction are not common. Unusual thermal Diels-Alder reactivity of arenes can be found in ... Other photochemical cycloaddition reactions with alkenes occur through excimers. Dearomatization[edit]. In dearomatization ... Arene reactions[edit]. Arenes are reactants in many organic reactions. Aromatic substitution[edit]. In aromatic substitution ... Coupling reactions[edit]. In coupling reactions a metal catalyses a coupling between two formal radical fragments. Common ...
Photogeneration, rearrangement, and cycloaddition reactions". J. Am. Chem. Soc. 98: 3564-3572. doi:10.1021/ja00428a029.. ... In one named reaction called the Ferrario reaction phenyl ether is converted to phenoxathiin by action of elemental sulfur and ... by reaction of tetramethyltellurium with xenon difluoride to TeF2(CH3)4 followed by reaction with dimethylzinc. The sulfur ... Certain aromatic thiols can be accessed through a Herz reaction. Disulfides R−S−S−R with a covalent sulfur to sulfur bond are ...
Cycloadditions and oxidation[edit]. Alkynes undergo diverse cycloaddition reactions. Most notable is the Diels-Alder reaction ... Other specialized cycloadditions include multicomponent reactions such as alkyne trimerisation to give aromatic compounds and ... Reactions specific for terminal alkynes[edit]. In addition to undergoing the reactions characteristic of internal alkynes, ... Other reactions are listed below. In some reactions, alkynes are less reactive than alkenes. For example, in a molecule with an ...
It is not typically isolated, but trapped by Diels-Alder reactions, e.g. with butadiene. Cycloadditions occur across the N=O ... The C-N-O angle is 113°. The NCN angle is 170°. The compound can be generated by the reaction of nitrosyl chloride and silver ...
Other reactions of nitrones are known, including formal [3+3] cycloadditions to form 6-membered rings, as well as formal [5+2] ... As 1,3-dipoles, nitrones are useful in 1,3-dipolar cycloadditions. Upon reaction of a nitrone with an alkene dipolarophile, an ... The general structure is R1R2C=NR3+O− where R3 is not H. A nitrone is a 1,3-dipole, and is used in 1,3-dipolar cycloadditions. ... This issue is alleviated experimentally by employing an excess of the nitrone or increasing the reaction temperature to ...
The [4+4] Photocycloaddition is a cycloaddition reaction in which two unsaturated molecules connect via four atoms from each ... Inevitably, [4+4] photocycloadditions carry the side reaction of [2+2] photocycloadditions. However, since these reactions are ... As a photochemical reaction, it is promoted by some form of light, as opposed to a thermal process. The earliest example of a [ ... 4+4] reactions are forbidden in the ground state and often entropically disfavored in the excited state. The mechanism of the [ ...
The components of all pericyclic reactions, including sigmatropic reactions and cycloadditions, and electrocyclizations, can be ... The reaction center can be a p- or spn-orbital (Woodward-Hoffmann symbol ω), a conjugated system (π) or even a sigma bond (σ). ... the relationship between two simultaneous chemical bond making and/or bond breaking processes in or around a reaction center. ...
The first was a ruthenium-catalyzed intermolecular [2+2+2] cycloaddition reaction between two acetylenic units, A and B, and ... cycloaddition reaction between an o-quinone and the tetrasubstituted olefin within the intermediate, forming the macrocyclic ... Nicolaou's group and used a highly stereoselective and convergent strategy that involved two cycloaddition reactions. ...
... also reacts with dienophile singlet oxygen in a [4+2]-cycloaddition (Diels-Alder reaction): Chemical oxidation ... Rickborn, Bruce (1998). "The Retro-Diels-Alder Reaction Part I. C−C Dienophiles". Organic Reactions. pp. 1-393. doi:10.1002/ ... The reaction is affected by the presence of oxygen. ... cycloaddition. It reverts to anthracene thermally or with UV ... or o-methylene-substituted diarylketones in the so-called Elbs reaction. Reduction of anthracene with alkali metals yields the ...
In these conversions, it is proposed that small amounts of Fe2(CO)9 dissolve according to the following reaction: Fe2(CO)9 → Fe ... Fe2(CO)9 has also been employed in the synthesis of cyclopentadienones via a net [2+3]-cycloaddition from dibromoketones, known ... "Structure and Reactions of Fe2(CO)8: An IR Spectroscopic study using 13C Photolysis with plane-polarized light, and matrix ... as the Noyori [3+2] reaction. Low temperature UV/vis photolysis of Fe2(CO)9 yields the Fe2(CO)8 unsaturated complex, producing ...
The alcohol group was replaced by bromine in an Appel reaction which caused an elimination reaction (loss of HBr) to ... In this photochemical [4+2]cycloaddition, singlet oxygen was generated from oxygen and rose bengal and the intermediate ... The TIPS silyl enol ether 1.11 was formed by reaction with the triflate TIPSOtf and DBU in DMAP setting the stage for ... Treatment with hydrochloric acid formed ketone 3.13, reaction with Samarium(II) iodide gave ring-opening finally putting the ...
Consider the following reaction for example: CO + NO2 → CO2 + NO. In this case, experiments have determined that this reaction ... for reactions of ions in solution, measurement of the effect of ionic strength on the reaction rate[8][9] ... Reaction intermediates are often free radicals or ions. The kinetics (relative rates of the reaction steps and the rate ... In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical change occurs ...
Cycloadditions[edit]. The Diels-Alder reaction is commonly employed to functionalize C60. Reaction of C60 with appropriate ... Free radical reactions[edit]. Reactions of C60 with free radicals readily occur. When C60 is mixed with a disulfide RSSR, the ... Reaction of C60 with 9,9′,10,10′-dihydroanthracene under the same conditions, depending on the time of reaction, gives C60H32 ... Cyclopropanation (Bingel reaction)[edit]. Cyclopropanation (the Bingel reaction) is another common method for functionalizing C ...
2 Reactions *2.1 Copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). *2.2 Strain-promoted azide-alkyne cycloaddition (SPAAC ... Main article: Azide alkyne Huisgen cycloaddition. The classic[11][12] click reaction is the copper-catalyzed reaction of an ... This reaction proceeds as a concerted [3+2] cycloaddition in the same mechanism as the Huisgen 1,3-dipolar cycloaddition. ... Reactions[edit]. For a reaction to be considered a click reaction, it must satisfy certain characteristics:[3] ...
... cycloaddition reactions with early example the cycloaddition of an nitrile oxide with an alkyne. Other reactions are the use of ... asymmetric aldol reaction. In contrast to the other reactions described above, this reaction does not involve activation of a C ... For instance, Hashmi reported a AuCl3-catalyzed alkyne / furan Diels-Alder reaction - a type of cycloaddition that does not ... Ito, Y.; Sawamura, M.; Hayashi, T. (1986). "Catalytic asymmetric aldol reaction: Reaction of aldehydes with isocyanoacetate ...
CycloadditionsEdit. Cycloaddition reaction are not common. Unusual thermal Diels-Alder reactivity of arenes can be found in the ... Other photochemical cycloaddition reactions with alkenes occur through excimers. DearomatizationEdit. In dearomatization ... ReactionsEdit. Aromatic ring systems participate in many organic reactions. Aromatic substitutionEdit. In aromatic substitution ... Many methods rely on cycloaddition reactions. Alkyne trimerization describes the [2+2+2] cyclization of three alkynes, in the ...
Diels-Alder reaction. *Pauson-Khand reaction. *Azide-alkyne Huisgen cycloaddition. *Sonogashira coupling ...
Cheletropic reactions are a subclass of cycloadditions. What sets cheletropic reactions apart is that on one of the reagents, ... Cheletropic reactions are a type of pericyclic reaction where one atom on one of the reagents gets two new bonds. A pericyclic ... Reactions were done at 120 °C and were studied by 1H-NMR spectroscopy of the reaction mixture. The forward rate k1 was found to ... The reaction rate constants of the forward and reverse reaction in addition to the equilibrium constants were found to be ...
Hosomi-Sakurai reaction. *Houben-Fischer synthesis. *Hudlicky fluorination. *Huisgen cycloaddition. *Hunsdiecker reaction, ... Retrieved from "https://en.wikipedia.org/w/index.php?title=List_of_organic_reactions&oldid=936402796" ...
Kinetically, catalytic reactions are typical chemical reactions; i.e. the reaction rate depends on the frequency of contact of ... A catalyst works by providing an alternative reaction pathway to the reaction product. The rate of the reaction is increased as ... The intermediate reaction states were: HO2, H2O2, then H3O2 and the final reaction product (water molecule dimers), after which ... Although the catalyst is consumed by reaction 1, it is subsequently produced by reaction 4, so it does not occur in the overall ...
3-dipolar cycloaddition products. The Dakin-West reaction is a reaction of an amino acid with an acid anhydride in the presence ... cycloaddition. Ketene [2 + 2] cycloadditions can be difficult reactions and give poor yields due to competing processes. The ... Ketene [2 + 2] cycloaddition reactions have been used in many total syntheses since Corey's use of the [2 + 2] cyclization in ... Ketenes are able to undergo what is normally considered a forbidden [2 + 2] cycloaddition reaction because the ketene acts in ...
Addition reactions. Electrophilic addition · Nucleophilic addition · Free radical addition · Cycloaddition. Related topics. ... Reaction kinetics[change , change source]. The rate of an SN2 reaction is second order, as the rate-determining step depends on ... Reaction mechanism[change , change source]. The reaction most often occurs at an aliphatic sp3 carbon center with an ... Factors affecting the rate of the reaction[change , change source]. Four factors affect the rate of the reaction: *Substrate. ...
Some proponents of nanorobotics, in reaction to the grey goo scenarios that they earlier helped to propagate, hold the view ... 3-Dipolar Cycloadditions: Effect of Interfacial Interactions on Molecular Motion". ACS Nano. 5 (1): 622-630. doi:10.1021/ ...
... s can, typically in the presence of suitable catalysts, serve as partners in cycloaddition reactions. The aldehyde ... Various reactions, for example the Vilsmeier-Haack reaction. Nef reaction Nitro compounds The acid hydrolysis of a primary ... Related reactions include organostannane additions, Barbier reactions, and the Nozaki-Hiyama-Kishi reaction. ... More complex reactions[edit]. Reaction name. Product. Comment Wolff-Kishner reduction Alkane If an aldehyde is converted to a ...
The reaction is thought to proceed via proton transfer from carboxylic acid to diazomethane to give methyldiazonium cation, ... It readily takes part in 1,3-dipolar cycloadditions. Preparation. Diazomethane laboratory preparation ... Since proton transfer is required and rate limiting, this reaction exhibits high specificity for carboxylic acids over less ... The Buchner-Curtius-Schlotterbeck reaction @ Institute of Chemistry, Skopje, Macedonia. *Identification of Artifacts (By- ...
α,α'-Dihaloketones eliminate HX under the reaction conditions to give α,β-unsaturated carbonyl compounds. The reaction ... Trimethylenemethane cycloaddition which can proceed via a similar mechanism Favorskii, A. E. J. Russ. Phys. Chem. Soc. 1894, 26 ... The photo-Favorskii reaction has been used in the photochemical unlocking of certain phosphates (for instance those of ATP) ... Cope, Arthur (1960). Organic Reaction Volume XI (1 ed.). New York: Wiley-Interscience. doi:10.1002/jps.2600500225. ISBN ...
Other reactionsEdit. Vinyl acetate undergoes many of the reactions anticipated for an alkene and an ester. Bromine adds to give ... 2 cycloadditions. ... The main side reaction is the combustion of organic precursors ... The major industrial route involves the reaction of ethylene and acetic acid with oxygen in the presence of a palladium ... "Elucidation of the Reaction Mechanism for the Palladium‐Catalyzed Synthesis of Vinyl Acetate". Angewandte Chemie International ...
An important example of cycloaddition reaction is the Diels-Alder reaction (the so-called [4+2] cycloaddition) between a ... For example, the water gas shift reaction CO. (. g. ). +. H. 2. O. (. v. ). ↽. −. −. ⇀. CO. 2. (. g. ). +. H. 2. (. g. ). {\ ... Photochemical reactions include hydrogen-oxygen reactions, radical polymerization, chain reactions and rearrangement reactions. ... Elementary reactions. The elementary reaction is the smallest division into which a chemical reaction can be decomposed, it has ...
The Diels-Alder reaction of β-nitrostyrene and cyclopentadiene is described in a number of early papers.[8][9] ... Thus, the Diels-Alder cycloaddition leads to a product in which the nitro- and phenyl- groups are in a trans- relationship to ... Fencamfamin may be synthesized in a straightforward fashion via the Diels-Alder reaction between cyclopentadiene and β- ... Originally achieved under reductive amination conditions involving the reaction of the amine with acetaldehyde in the presence ...
Two key chemical transformations are the Shapiro reaction and the pinacol coupling reaction. The overall synthesis was ... Boron served as a molecular tether and aligned both diene and dienophile for this endo Diels-Alder cycloaddition. After ... As shown in Scheme 1, the ring synthesis of ring C began with a Diels-Alder reaction between diene 1.3 and dienophile 1.1 in ... The oxetane ring in compound 6.3 was obtained via an SN2 reaction involving a mesylate derived from acetate 4.9. Ring B was ...
... pericyclic reactions include cycloadditions, electrocyclic reactions and sigmatropic rearrangements. Although some of the ... A cascade reaction, also known as a domino reaction or tandem reaction, is a chemical process that comprises at least two ... In cascade reactions, isolation of intermediates is not required, as each reaction composing the sequence occurs spontaneously ... Gold-catalyzed formal intramolecular [4+2] cycloaddition of 1,6-enynes This formal cycloaddition was proposed to proceed via ...
... it is possible that the HCCPD could react directly with cellular alkenes in a cycloaddition reaction. This might then explain ... This reaction is used to produce pesticides such as Aldrin (named after the reaction) and Isodrin. Most of these pesticides are ... Reactions[edit]. HCCP is electrophilic. It degrades in base. Alcoholysis affords ketals C5Cl4(OR)2.[9] ... In surface water, photolysis is the most common reaction route, with a degradation half-life of 2 to 4 minutes.[6] Deeper under ...
The first synthetic β-lactam was prepared by Hermann Staudinger in 1907 by reaction of the Schiff base of aniline and ... benzaldehyde with diphenylketene in a [2+2] cycloaddition (Ph indicates a phenyl functional group): Up to 1970, most β-lactam ...
By reaction of alkenes with hydrazoic acid in the Schmidt reaction.. *By reaction of a nitrile, hydrochloric acid, and an arene ... The C=N bond in imines is reactive toward cycloadditions. Imines react, thermally, with ketenes in [2+2] cycloadditions to form ... Imines participate in many reactions that are analogous to the reactions of aldehydes and ketones: *An imine is reduced in ... Imine react with dialkylphosphite in the Pudovik reaction and Kabachnik-Fields reaction ...
Addition reactions. Electrophilic addition · Nucleophilic addition · Free radical addition · Cycloaddition. Related topics. ... zero-order reaction: the speed does not depend on the concentration. *first-order reaction: the speed depends on the ... This states that for a reaction to happen, the molecules must hit each other. Ways of increasing the speed of the reaction must ... Chemical kinetics, also called reaction kinetics, is studying how fast chemical reactions go. This includes studying how ...
An important example of cycloaddition reaction is the Diels-Alder reaction (the so-called [4+2] cycloaddition) between a ... For example, the water gas shift reaction CO. (. g. ). +. H. 2. O. (. v. ). ↽. −. −. ⇀. CO. 2. (. g. ). +. H. 2. (. g. ). {\ ... Photochemical reactions include hydrogen-oxygen reactions, radical polymerization, chain reactions and rearrangement reactions. ... A special arrow (⇒) is used in retro reactions.[9] Elementary reactions. The elementary reaction is the smallest division into ...
This proceeds via a [3 + 2] cycloaddition reaction between the OsO4 and alkene to form an intermediate osmate ester which ... Reaction of bulk solid requires heating to 400 °C.[11] Os. +. 2. O. 2. →. Δ. T. OsO. 4. {\displaystyle {\ce {Os + 2O2 -,[\Delta ... Reactions[edit]. Oxidation of alkenes[edit]. Alkenes add to OsO4 to give diolate species that hydrolyze to cis-diols. The net ... See reaction and mechanism above. This reaction has been made both catalytic (Upjohn dihydroxylation) and asymmetric (Sharpless ...
The 1,3-dipolar cycloaddition reaction of cyclopropanes and nitrones to give tetrahydro-1,2-oxazine has been studied with ... Home » The mechanism of 1,3-dipolar cycloaddition reactions of cyclopropanes and nitrones â€" A theoretical study ... The mechanism of 1,3-dipolar cycloaddition reactions of cyclopropanes and nitrones â€" A theoretical study. ... Trends in the calculated barriers for the reaction were in good agreement with available trends in the reaction rates measured ...
... Wang Yong;Li Hao-Ran;Wang Cong-Min;Xu ... Key words: Density functional theory, Cycloaddition reaction, Transition states, Dibromocabene, B3LYP level ... Abstract: The mechanisms of cycloaddition reactions of singlet dibromocarbene and formaldehyde have been studied using density ... Quantum Chemistry Study on the Cycloaddition Reaction of Dibromocarbene and Formaldehyde[J].Acta Phys. -Chim. Sin., 2004, 20(11 ...
Organocatalytic 1,3-dipolar cycloaddition reactions of ketones and azides with water as a solvent. August 21, 2013. August 21, ... HomeOrganocatalytic 1,3-dipolar cycloaddition reactions of ketones and azides with water as a solvent ... We reported an enamine catalyzed strategy to fully promote a 1,3-dipolar cycloaddition to access a vast pool of substituted 1,2 ... Atom- and step-economical nucleophilic arylation of azaaromatics via electrochemical oxidative cross C-C coupling reactions ...
Carbene and silicon routes as methods for the generation and dipolar cycloaddition reactions of methyl nitrile ylide. Journal ... Carbene and silicon routes as methods for the generation and dipolar cycloaddition reactions of methyl nitrile ylide. In: ... Carbene and silicon routes as methods for the generation and dipolar cycloaddition reactions of methyl nitrile ylide. / Padwa, ... title = "Carbene and silicon routes as methods for the generation and dipolar cycloaddition reactions of methyl nitrile ylide", ...
Catalyzed Alkyne-Azide Cycloaddition Reactions.- J. D. Crowley and D. A. McMorran: ... B. R. Buckley and H. Heaney: Mechanistic Investigations of Copper(I)- Catalyzed Alkyne-Azide Cycloaddition Reactions.- J. D. ...
... bioorthogonal reactions have emerged as a powerful toolbox for specific labeling and visualization of biomolecules, even within ... Bioorthogonal reaction Transition metal Cycloaddition reaction CuAAC reaction Unnatural amino acids Maiyun Yang and Yi Yang ... Gao M, He C, Chen H, Bai R, Cheng B, Lei A (2013) Synthesis of pyrroles by click reaction: silver-catalyzed cycloaddition of ... Song W, Wang Y, Qu J, Madden MM, Lin Q (2008) A photoinducible 1,3-dipolar cycloaddition reaction for rapid, selective ...
... This video was recorded at CHEM 125b: ... Disciplines with similar materials as Lecture 19 - Aromatic Transition States: Cycloaddition and Electrocyclic Reactions ... Other materials like Lecture 19 - Aromatic Transition States: Cycloaddition and Electrocyclic Reactions ... Edit comment for material Lecture 19 - Aromatic Transition States: Cycloaddition and Electrocyclic Reactions ...
Cycloaddition Reaction of Ethyl Thioxoacetate and the Dienamine Derived from Pummerers Ketone,. Journal of Chemistry,. vol. ... Cycloaddition Reaction of Ethyl Thioxoacetate and the Dienamine Derived from Pummerers Ketone. With the aim of extending the ... reported [13] a related cycloaddition reaction. They found that the thioaldehydes having electron-withdrawing groups (ZCHS; Z= ... Cycloaddition Reaction of Ethyl Thioxoacetate and the Dienamine Derived from Pummerers Ketone. ...
Emphasizes the use of carbohydrate-derived substrates in cycloaddition reactions. Valuable reading for anyone interested in the ... and intramolecular Diels-Alder reactions, dipolar addition reactions, and the use of carbohydrate-derived chiral auxiliaries. ... Includes applications to the synthesis of natural products and examines the stereochemical aspects of cycloaddition processes. ... Provides discussions on recent advances in the cycloaddition chemistry of carbohydrates, including inter- ...
Since the shop Cycloaddition Reactions of Heterocumulenes 1967( pad health, or Auto) option needs shorter, we can need three- ... There gave far great shop Cycloaddition Reactions, incredibly astrological bt. 30-35 shop Cycloaddition Reactions of ... shop Cycloaddition Reactions posts are deeper into our opinions, so all far infected to be our files on annualized cross-asset ... After getting shop Cycloaddition Reactions week futures, are However to go an chunky Buying to learn normally to insights you ...
... Shuai Yuan,1 Huiling Hong,1 ... The [2 + 2] photocycloaddition reaction of benzene and ethylene was investigated by semiclassical dynamics simulation and ...
Suppression of Metallic Conductivity of Single-Walled Carbon Nanotubes by Cycloaddition Reactions ... Suppression of Metallic Conductivity of Single-Walled Carbon Nanotubes by Cycloaddition Reactions ... Suppression of Metallic Conductivity of Single-Walled Carbon Nanotubes by Cycloaddition Reactions ... Suppression of Metallic Conductivity of Single-Walled Carbon Nanotubes by Cycloaddition Reactions ...
The nitrilimine-alkene cycloaddition is an ultra rapid click reaction† Xiaoshan Shayna Wang,a Yan-Jiun Leea and Wenshe R. Liu*a ... The nitrilimine-alkene cycloaddition is an ultra rapid click reaction X. S. Wang, Y. Lee and W. R. Liu, Chem. Commun., 2014, 50 ...
729e) Solvent Effects on Intermolecular Mpvo and Cycloaddition Reactions in Zeolites with Different Intrapore Polarity. * ... on reactions in condensed media using the intermolecular MPVO reaction between 2-butanol and cyclohexanone as a probe reaction ... Solvent polarity plays a critical role for many heterogeneously catalyzed reactions of oxygenated molecules derived from ... which can modify free energy barriers for a variety of different reactions. ...
... cycloaddition reactions of tert-butylcyanoketene (TBCK) with different ketenophiles have been studied. Cycloaddition of mono ... 1990) Cyanoketene cycloaddition reactions. Masters thesis, King Fahd University of Petroleum and Minerals. ... Evern though the addition reaction of TBCK with phenylacetylene gave cyclobutanone in good yield, the corresponding reaction ... Addition reaction of TBCK with 1,1-disubstituted alkenes having t-butyldimethylsiloxy, or benzyloxy group attached to allylic ...
... could improve the DA cycloaddition reaction with 1,3-butadiene. The substituents tested include electron-donating (NH2, OMe, OH ... The most promising results were obtained for the NO2 substituent; the activation energy barriers for reactions using this ... This leads us to expect that the cycloadditions to a starting fullerene fragment will be possible. ... kinetic and thermodynamic parameters of the DA reactions of the substituted hemifullerenes with 1,3-butadiene have been ...
... pyrazines by a catalyst-free three-component Strecker reaction followed by an intramolecular [3+2] cycloaddition. The first ... Synthesis of decahydropyrrolo[1,2-a]tetrazolo[1,5-d]pyrazines via Strecker reaction and intramolecular [3+2] cycloaddition ... Synthesis of decahydropyrrolo[1,2-a]tetrazolo[1,5-d]pyrazines via Strecker reaction and intramolecular [3+2] cycloaddition S. N ... pyrazines by a catalyst-free three-component Strecker reaction followed by an intramolecular [3+2] cycloaddition. The first ...
Conference Paper: Vinylsulfonates in the carbene cyclization cycloaddition cascade reaction. *Show simple item record ...
Notably, the phosphine oxides are reduced during the course of the reaction. A comparison to the analogous chemistry of alkenes ... cycloaddition where the (di)tetrelene acts as the 2p component and the nitro/nitrone act as the 4p component. In some cases, ... Farhadpour, Bahareh, "Doubly Bonded Derivatives of Si and Ge: Cycloaddition Reactions and Polymer Chemistry" (2017). Electronic ... Doubly Bonded Derivatives of Si and Ge: Cycloaddition Reactions and Polymer Chemistry ...
Asymmetric catalysis of the [5+2] cycloaddition reaction of vinylcyclopropanes and pi-systems. ... Asymmetric catalysis of the [5+2] cycloaddition reaction of vinylcyclopropanes and pi-systems. ... Asymmetric catalysis of the [5+2] cycloaddition reaction of vinylcyclopropanes and pi-systems ...
The reaction is typically promoted by stoichiometric or greater amounts of acids, such as AlCl3, FeCl3, or H2SO4, which ... Cycloaddition of allylic azides and alkynes. The 1,3-dipolar Huisgen azide-alkyne cycloaddition is a significant area of ... The use of allylic azides as dynamic reaction partners represent a novel variant of this chemistry as they undergo facile 1,3- ... The Friedel-Crafts acylation is one of the most important reactions in both academia and industry for the synthesis of aromatic ...
3-dipole cycloaddition reactions. A couple of years ago Ess and Houk described computations on the cycloaddition reactions of ... One Response to "Understanding 1,3-dipole cycloaddition reactions". * Henry Rzepa. responded on 07 Jul 2010 at 1:24 am # ... is the one associated with the cycloaddition reaction, as it is set up for making the two new bonds at the terminal positions. ... even though the reactions are quite different in overall reaction energies. This implies a violation of the Hammond Postulate. ...
The copper-catalyzed azide-alkyne cycloaddition click reaction is studied in one-pot eliminating the need to isolate and handle ... Continuous metal scavenging and coupling to one-pot copper-catalyzed azide-alkyne cycloaddition "click" reaction in flow ... Coupling reactions of this type with a downstream work-up demonstrate effective process intensification. The group describes a ... Process integration is achieved by coupling this unit downstream to a flow reaction using homogeneous metal-based catalysis, i. ...
3-dipolar cycloaddition "click" reaction. The synthetic applications of the click reaction focus on multivalent carbohydrates ... Pieters, R.J., Rijkers, D.T.S. and Liskamp, R.M.J. (2007) Application of the 1,3-dipolar cycloaddition reaction in chemical ... Application of the 1,3-dipolar cycloaddition reaction in chemical biology: approaches toward multivalent carbohydrates and ... Furthermore, a related reaction is described involving the coupling of thio acids and sulfonyl azides leading to the ...
Bispericyclic reaction involving two [6+4] cycloadditions. Bispericyclic transition states arise when two pericyclic reactions ... cycloaddition leads to 4. A variety of [4+2] reactions are also possible. All of these reactions were investigated at PCM/M06- ... 2X/6-311+G(d,p)//B3LYP-D3/6-31G(d). The reaction leading to 3 is exothermic by 3.0 kcal mol-1, while the reaction to 4 ... This leads to a potential energy surface with a bifurcation such that reactions that traverse this type of transition state ...
3-dipolar cycloaddition reaction. Akeroyd N. ; Pfukwa R. ; Klumperman B. (2009) ...
POLYCYCLIC AROMATIC RING SYNTHESIS USING PALLADIUM CATALYZED C-H ACTIVATION AND ENAMINE-CATALYZED [3+2] CYCLOADDITION REACTIONS ... palladium catalysis, enamine catalysis, polyclic aromatic ring synthesis, cycloaddition reactions, C-H activation, heterocycles ... CYCLOADDITION REACTIONS IN HETEROCYCLES SYNTHESIS. [email protected] Repository.. Abstract: Huge advances have been made in the ... We have successfully explored a series of enamine catalyzed [3+2] cycloaddition. These pioneering works consisted by enamine- ...
Cycloaddition reactions are fundamental and substantial part of organic chemistry in research. Research work on the aza Diels ... Organo-catalytic [4+2] Aza Diels Alder Cycloaddition Reaction in an Environmentally Benign Solvent System. Author(s): Lembhale ... alder cycloaddition reactions in aqueous systems would be green pathway for organic processes and will definitely protect ...
Rhodium-Catalyzed Cycloaddition Reactions. The papers below report the discovery that rhodium catalyzes cycloaddition reactions ... Mechanism of Metal-Catalyzed Cycloaddition Reactions. The mechanism by which rhodium catalyzes cycloaddition reactions was ... 1. Joseph J. Mrowca and Thomas J. Katz, "Catalysis of a Cycloaddition Reaction by Rhodium on Carbon," J. Am. Chem. Soc. 1966, ... 4. Thomas J. Katz and Steven A. Cerefice "The Mechanism of a Metal-Catalyzed Cycloaddition Reaction," J. Am. Chem. Soc.1969, 91 ...
On the thick cycloaddition, in the empire of the travels, as the nuptial society; accused no surprising prejudices to the ... This cycloaddition reactions must be a early article to the iron; they was corrected rather to find the death of it Hence not ... The cycloaddition reactions between Charles the Bald and his virtues, is pardon not of views, who might have to pay so a ... If the open cycloaddition reactions in carbohydrate chemistry was to buy the gypt, not from spirit to soul, but for otherwise, ...
... learn a download Cycloaddition Reactions in Carbohydrate to be ... The download Cycloaddition Reactions in for the sign of insurance is the birth of rural leaders. The two most few employers of ... fascinating download Cycloaddition Reactions in Carbohydrate Chemistry can Need from the nuclear. If HER2, now the topic in its ... download Cycloaddition Reactions in Carbohydrate is the exchange of due lung to economic novel by higher Egyptologists, course ...
Video explaining Photochemical Cycloaddition Reactions for Organic Chemistry. This is one of many videos provided by Clutch ... Photochemical Cycloaddition reactions are pericyclic reactions in which 2 pi bonds are destroyed after a light-activated cyclic ... So, a photochemical cycloaddition is a pericyclic reaction in which 2 pi bonds are destroyed just like any cycloaddition but it ... 10 - Addition Reactions. 3hrs & 33mins. 0. % complete WorksheetStart. Ch. 11 - Radical Reactions. 1hr & 57mins. 0. % complete ...
Video explaining Thermal Cycloaddition Reactions for Organic Chemistry. This is one of many videos provided by Clutch Prep to ... Thermal Cycloaddition reactions are pericyclic reactions in which 2 pi bonds are destroyed after a heat-activated cyclic ... 10 - Addition Reactions. 3hrs & 33mins. 0. % complete WorksheetStart. Ch. 11 - Radical Reactions. 1hr & 57mins. 0. % complete ... So, thermal cycloadditions are pericyclic reactions in which two pi bonds are destroyed, by the way, we know that its two ...
The cycloaddition reactions of imidazolium-3-dicyanomethanide 1,3-dipoles with electron poor alkene and alkyne dipolarophiles ... Cycloaddition reactions of imidazolium and phthalazinium dicyanomethanide 1,3-dipoles: synthesis, mechanism and the effect of ... The cycloaddition reaction of the phthalazinium dicyanomethanide 1,3-dipole with benzylidene acetone dipolarophiles was also ... Cycloaddition reactions involving solid phthalazinium dicyanomethanide 1,3-dipole and the solid dipolarophiles p- ...
  • Vishwakarma Singh and co-workers from IIT Bombay have published in Organic and Biomolecular Chemistry on an oxidation of a phenol that yields a Diels-Alder substrate that dimerizes on itself and when the dimer is heated reforms the dienone substrate that undergoes an intramolecular Diels-Alder reaction. (wordpress.com)
  • This entry was posted on August 5, 2010 at 11:45 am and is filed under Antibiotics , Cascade Reactions , Cycloaddition , Diels-Alder , Hypervalent Iodine , Methodology , Named Reactions , Pericyclic reactions , retro-Diels-Alder . (wordpress.com)
  • We reported an enamine catalyzed strategy to fully promote a 1,3-dipolar cycloaddition to access a vast pool of substituted 1,2,3-triazoles in water. (wordpress.com)
  • Generation of the dipole from a silylthioimidate followed by dipolar cycloaddition also gave rise to related cycloadducts. (elsevier.com)
  • Unfortunately, all attempts to carry out cycloaddition with these substrates resulted in a rapid 1,4 silyl elimination to penta-l,3-diene. (bl.uk)
  • However, there are few functionalised alkenes which directly introduce the C-4 carbon substitution required for carbapenem synthesis upon cycloaddition with CSI. (bl.uk)
  • Earlier investigations within this group have shown that allylsilanes undergo regioselective cycloaddition with CSI to yield C-4 silylmethyl substituted beta-lactams.133,137 The regiochemistry of cycloaddition is controlled by the beta-effect of silicon, i.e., silicon's ability to stabilise the development of partial positive charge P to itself. (bl.uk)
  • We were intrigued by reports from Fleming142 and Taddei141 that allylsilanes bearing a chiral centre directly adjacent to the double bond undergo reaction with various electrophiles, including CSI, with remarkably high stereoselectivity. (bl.uk)
  • Of the numerous methods developed to achieve this, the [2+2] cycloaddition of chlorosulphonyl isocyanate (CSI) to functionalised alkenes has proven to be particularly useful. (bl.uk)
  • Methyl nitrile ylide was generated by both a photochemical and desilylation route and has been characterized by UV spectroscopy and by its kinetic and cycloaddition behavior. (elsevier.com)
  • B. R. Buckley and H. Heaney: Mechanistic Investigations of Copper(I)- Catalyzed Alkyne-Azide Cycloaddition Reactions. (springer.com)
  • abstract = "Cycloaddition reactions of 2,5-di-tert-butylthiophene S-oxide and 2,3,4,5-tetrakis(p-tolyl)thiophene S-oxide with alkenes are described. (coventry.ac.uk)
  • Here, we investigate the interplay of both solvent and framework polarity on reactions in condensed media using the intermolecular MPVO reaction between 2-butanol and cyclohexanone as a probe reaction. (aiche.org)
  • 5.4.1 Intermolecular [2+2] Cycloaddition. (wiley.com)
  • 5.4.5 Intermolecular and Intramolecular Cycloaddition of Ketenes with Carbonyl Groups. (wiley.com)
  • In order to solve this issue, we assumed that bicyclo[3.3.1]nonenone scaffolds can be directly obtained through an intermolecular Diels-Alder reaction/Au(I)-catalyzed 6- endo-dig carbocyclization ( Scheme 3 ). (beilstein-journals.org)
  • 2019) Organophotoredox-Catalyzed Intermolecular Oxa-[4+2] Cycloaddition Reactions. (news-medical.net)
  • Gold-catalyzed Intermolecular [4C + 3C] Cycloaddition Reactions. (biomedsearch.com)
  • Transition metal-mediated cycloaddition and cyclization reactions are then used to convert these substrates to 10 distinct classes of polycyclic scaffolds that are primed for further functionalization. (pnas.org)
  • Recently, we have found that primary amines (such as amino-acids, amino-esters, hydroxylamine) can be used to condense with an aldehyde and promote a cascade process involving imine formation, cyclization, ylide formation and cycloaddition all in one pot. (sheffield.ac.uk)
  • Alonso, J.A. The Diels-Alder Cycloaddition Reaction of Substituted Hemifullerenes with 1,3-Butadiene: Effect of Electron-Donating and Electron-Withdrawing Substituents. (mdpi.com)
  • The aim of the present study is to extend and explore the regiochemistry and stereochemistry of the reaction of ethyl thioxoacetate (3) with unsymmetrical diene, which is the dienamine (19) derived from Pummerer's ketone. (hindawi.com)
  • With the aim of extending the study of thioxoacetate ester reactions with unsymmetrical conjugated dienes, a diene substituted in the 2-H position with an amino group was selected. (hindawi.com)
  • These diene complexes are competent precatalysts for (i) the selective cross-[2+2]-cycloaddition of butadiene or (E)-piperylene with ethylene and α-olefins and (ii) the 1,4-hydrovinylation of isoprene with ethylene. (princeton.edu)
  • Possible relationships between ligand-controlled diene coordination geometry, metallacycle denticity, and chemoselectivity of iron-mediated cycloaddition reactions are discussed. (princeton.edu)
  • The reactivity of 2,5-di-tert-butylthiophene S-oxide as diene in Diels-Alder reactions is compared with 2,5-di-tert-butylthiophene S,S-dioxide. (coventry.ac.uk)
  • Cycloaddition between diene 12 and dienophile 13 should provide the endo cycloadduct 14 , which, in the presence of a gold(I) catalyst, would form the gold complex A . This undergoes a carbocyclization of enol ether [24-31] to afford intermediate B , which after proto-deauration and hydrolysis affords the bridgehead ketone 15 . (beilstein-journals.org)
  • Cycloaddition of TBCK with cyclic nitrones afforded a complicated mixture of intractable products. (edu.sa)
  • Photochemical Cycloaddition reactions are pericyclic reactions in which 2 pi bonds are destroyed after a light -activated cyclic mechanism. (clutchprep.com)
  • So, a photochemical cycloaddition is a pericyclic reaction in which 2 pi bonds are destroyed just like any cycloaddition but it only occurs after a light-activated cyclic mechanism. (clutchprep.com)
  • So, thermal cycloadditions are pericyclic reactions in which two pi bonds are destroyed, by the way, we know that it's two because the cycloaddition, they always destroy two pi bonds, after a heat-activated cyclic mechanism. (clutchprep.com)
  • Now, very quickly, I do want to show you guys the mechanism, the mechanism would have to, it would be a cyclic concerted reaction where all of your double bonds are forming new bonds within the system to make a new ring. (clutchprep.com)
  • A reaction that forms an arene compound from an unsaturated or partially unsaturated cyclic precursor is simply called an aromatization . (wikipedia.org)
  • A Lewis acid catalysed rearrangement reaction of cobalt-alkyne complexes bearing a cyclic enol ether unit has been developed that provides a direct and stereoselective route to 3-alkynylcycloalkanones. (sheffield.ac.uk)
  • Regiochemistry, stereochemistry, and kinetics show that two new sigma bonds are being formed simultaneously, if not symmetrically, in the 6-electron Diels-Alder cycloaddition. (merlot.org)
  • Two other features are well covered as well: the transformation of cycloaddition products into other forms of products and stereochemistry of these cycloaddition reactions. (blogspot.com)
  • The mechanism of the cycloaddition or the cycloreversion does not seem to have a unified mechanism. (edu.sa)
  • The mechanism of the cycloaddition reaction between singlet dimethyl-silylene carbene and acetone has been investigated with density functional theory, From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. (ustc.edu.cn)
  • Primary and secondary amines as catalysis in the cycloaddition transformation of biological and pharmaceutical compounds via the iminmium activation model have been greatly explored. (nus.edu.sg)
  • These Michael Addition reactions generated unstable intermediates that underwent in situ 1,2-rearrangment to form the new spirally twisted imidazolium ylide compounds. (nuigalway.ie)
  • It was observed that enediynes type yne-ene-yne preferred the standard [2+2+2] cycloaddition reaction, while enediynes type yne-yne-ene suffered β-hydride elimination followed a reductive elimination of Wilkinson's catalyst giving cyclohexadiene compounds, which are isomers from those that would be obtained through standard [2+2+2] cycloaddition reactions. (udg.edu)
  • Finally, the last chapter of this thesis is based on the use of DFT calculations to determine the reaction mechanism when the macrocycles are treated with transition metals that are inactive to the [2+2+2] cycloaddition reaction, but which are thermally active leading to new polycyclic compounds. (udg.edu)
  • Cycloadditions with ketenophiles in the [4 + 2] or [2 + 2] mode and electrocyclizations of dienylketenes are atom economical approaches to the construction of ring systems in organic compounds. (organicreactions.org)
  • The thermal and photochemical SO extrusion reactions of the cycloadducts under formation of highly substitutedaromatic compounds are exemplified. (coventry.ac.uk)
  • We have developed a strategically novel approach to these compounds through cycloaddition reactions of alkynylboronates. (sheffield.ac.uk)
  • This study deals with the (4+2)-cycloaddition reactions of 4-π electron compounds with ketenes. (unt.edu)
  • Process integration is achieved by coupling this unit downstream to a flow reaction using homogeneous metal-based catalysis, i.e. presenting a continuous uninterrupted metal scavenging unit. (syrris.com)
  • Two classes of ligands were identified: those that give rise to high reaction rates in coordinating solvents but inhibit the process when used in excess relative to copper and those that provide for fast catalysis in water and are not inhibitory in excess. (scripps.edu)
  • Both imine and enole intermediate join in a cycloaddition reaction followed by an intramolecular nucleophilic acyl substitution of the amine with expulsion of the chiral auxiliary to the cis-lactam. (wikipedia.org)
  • The current MEDT study makes it possible to extend Domingo's classification of 32CA reactions to a new pseudo(mono)radical type ( pmr-type ) of reactivity. (mdpi.com)
  • The Diels-Alder (DA) reaction provides an attractive route to increase the number of six member rings in substituted Polycyclic Aromatic Hydrocarbons (PAHs). (mdpi.com)
  • The reaction is typically promoted by stoichiometric or greater amounts of acids, such as AlCl3, FeCl3, or H2SO4, which activate the carbonyl for attack by an aromatic group. (ku.edu)
  • Aromatic ring systems participate in many organic reactions. (wikipedia.org)
  • Intramolecular cycloaddition sets up two new rings and up to four new stereocentres in a single step. (sheffield.ac.uk)
  • The 1,3-dipolar cycloaddition reaction of cyclopropanes and nitrones to give tetrahydro-1,2-oxazine has been studied with density functional theory calculations at the B3LYP/6-31+G(d,p) level of theory. (ebscohost.com)
  • This learning unit introduces electrocyclic reactions as a class of pericyclic reactions. (chemgapedia.de)
  • We combined such an allylic azide rearrangement with an intramolecular Huisgen cycloaddition to afford substituted triazoles in a diastereoselective fashion. (ku.edu)
  • The following article will provide a brief summary of recent disclosures on this process featuring chemo-, regio- and diastereoselective oxyallyl cycloadditions with both electron-rich and electron-deficient 2π partners. (dartmouth.edu)
  • Next, one of the polyesters was employed as a polymeric platform in copper free cycloaddition reactions like, Huisgen type 1,3-dipolar and Diels-Alder cycloaddition reactions in the presence of various dipoles and dienes, respectively. (itu.edu.tr)
  • The [2 + 2] photocycloaddition reaction of benzene and ethylene was investigated by semiclassical dynamics simulation and complete active space self-consistent field (CASSCF) ab initio calculations. (hindawi.com)
  • The gas-phase cycloaddition reactions of ethylene and 1,3-butadiene with the cyclopropylcarbinyl cation to produce the cyclohexyl and cycloocten-5-yl cation, respectively, have been computationally characterized. (umn.edu)
  • The non-polar 32CA reaction of AI with ethylene takes place through a one-step mechanism with moderate activation energy, 8.7 kcal·mol −1 . (mdpi.com)
  • The hetero-Diels-Alder reactions of 1,2-diaza-1,3-butadiene with ethylene, methyl vinyl ether, and methyl acrylate have been investigated theoretically with the aid of density functional theory using the Becke3LYP/6-31G(d) computational level. (elsevier.com)
  • The most important application of this reaction is the addition of chlorine to ethylene to give 1,2-dichloroethane, from which vinyl chloride is prepared. (britannica.com)
  • One source of industrial ethanol, for example, is the reaction of ethylene with water in the presence of phosphoric acid . (britannica.com)
  • 1. Reactions of Aldehydes and Ketones and their Derivatives ( A. C. Knipe ). (wiley.com)
  • d-unsaturated carboxylic acid derivatives, 2-indanones, and fused cyclobutanones under remarkably mild reaction conditions. (csun.edu)
  • In general, the addition of the 1,3-dipolar nitrogen oxides to the (di)tetrelene gave 5-membered ring adducts via a formal [3+2] cycloaddition where the (di)tetrelene acts as the 2p component and the nitro/nitrone act as the 4p component. (uwo.ca)
  • Notably, the phosphine oxides are reduced during the course of the reaction. (uwo.ca)
  • Chemical Equation Presented) A [3 + 2] cycloaddition reaction between alkynyldimethylsilyl ethers and aryl and alkyl nitrile oxides to produce isoxazolylsilanols has been developed. (illinois.edu)
  • These pioneering works consisted by enamine-promoted inverse-electron-demand [3+2] cycloaddition-from diazocarbonyls to pyrazoles and enamine-catalyzed [3+2] cycloaddition to assemble highly substituted 1,2,3-triazoles from phenyl azides and ketones. (nus.edu.sg)
  • The reaction of nickel enolates displaying a metallacyclic structure with the α,β-unsaturated ketones methyl vinyl ketone (MVK) or methyl propenyl ketone (MPK) takes place in two stages, affording initially bicyclic adducts, which subsequently isomerize to the corresponding open-chain products. (csic.es)
  • The density functional theory (DFT) B3LYP method has been used in this work to inquire if the substitution of H over the edge of triindenetriphenylene (pristine hemifullerene 1 ) and pentacyclopentacorannulene (pristine hemifullerene 2 ), could improve the DA cycloaddition reaction with 1,3-butadiene. (mdpi.com)
  • 11. "Substitution and Elimination Reactions of Bicyclo[3.2.1]octyl-3 Tosylate," S.N.Y. Fanso-Free and G.W. Gribble, 6th Northeast Regional American Chemical Society Meeting, Burlington, Vermont, August 18-21, 1974. (dartmouth.edu)
  • Meanwhile, other transition metals such as ruthenium, rhodium and silver are now under development as alternative sources for catalyzing bioorthogonal cycloadditions. (springer.com)
  • The development of additional transition metals in catalyzing cycloaddition reactions will also be briefly introduced. (springer.com)
  • Recent Multiple Transition Metal Catalysed Single-Pot Reactions. (ebscohost.com)
  • Bispericyclic transition states arise when two pericyclic reactions merge to a common transition state. (comporgchem.com)
  • This leads to a potential energy surface with a bifurcation such that reactions that traverse this type of transition state will head towards two different products. (comporgchem.com)
  • Houk and coworkers have now identified a bispericyclic transition state involving two [6+4] cycloadditions. (comporgchem.com)
  • Interestingly, there is only one transition state that leads to both 3 and 4 , the first known bispericyclic transition state for two conjoined [6+4] cycloadditions. (comporgchem.com)
  • Experimentally and theoretically derived Hammett plots ruled out increased polarity of the cycloaddition transition state as the cause of rate accelerations observed in the presence of water. (nuigalway.ie)
  • At levels of theory up to MP2/cc-pVDZ the reactions are quite asynchronous but are concerted (i.e., there is only one transition state prior to formation of the product carbocycles). (umn.edu)
  • 2+2+2] Cycloaddition Reactions of Macrocyclic Systems Catalyzed by Transition Metals. (recercat.cat)
  • Reaction of the substituted syn tricyclic system 1 via the trapezoidal and synchronous transition state 6 is predicted as a potential experimental test of this new reaction mode. (rsc.org)
  • This procedure was followed by calculation of the force constant matrix and normal coordinate analysis to characterize the stationary point, and an intrinsic reaction coordinate calculation along the first normal mode direction to verify the identity of the reactants and products deriving from the transition state for selected examples. (rsc.org)
  • In contrast, the [4 + 2]-cycloaddition of 1,2-diaza-1,3-butadiene with methyl acrylate have been found to occur with low regio- and stereoselectivity but with a s-cis preference in the transition structures. (elsevier.com)
  • DFT modeling of the latter reaction provides further support for a quasi-concerted cycloaddition mechanism, displaying a nonsymmetric transition state in which the C-C and the C-O bond are formed in an asynchronous manner. (csic.es)
  • The (3+2)-cycloaddition reaction involving oxyallyl cations has proven to be a versatile and efficient approach for the construction of five-membered carbo- and heterocycles, which are prevalent frameworks in natural products and pharmaceuticals. (dartmouth.edu)
  • This reaction was particularly attractive because it can hold a high number of atoms and provides efficient access to various synthetically useful oxygen-containing heterocycles,' Hoshino said. (news-medical.net)
  • Red-light reactions could drive a higher production of heterocycles, but it requires more accuracy and efficiency. (news-medical.net)
  • Cycloadditions and electrocyclizations of conjugated ketenes establish carbon-based or heteroaromatic rings from vinylketenes, allenylketenes, or alkynylketenes. (organicreactions.org)
  • Because of the linear geometry of ketenes and their perpendicular C=C and C=O π systems, they are ideally suited for antarafacial [2 + 2] cycloaddtion reactions. (organicreactions.org)
  • Conjugated ketenes can react in a similar manner, but may also serve as the 4π component in [4 + 2] cycloaddition reactions or engage in 4π or 6π electrocyclization (Eq. 1). (organicreactions.org)
  • This summary focuses on the cycloaddition and electrocyclization reactions of conjugated ketenes, including vinylketenes, alkynylketenes, and allenylketenes. (organicreactions.org)
  • Cycloadditions of ketenes and alkenes may involve either concerted or stepwise pathways, and it is often difficult to distinguish the two mechanistic possibilities. (organicreactions.org)
  • and new sections on cycloaddition reactions, ketenes from esters, ketene reactions using polymer supports, and oxoquinone methides. (wiley.com)
  • 5.4 Cycloaddition Reactions of Ketenes. (wiley.com)
  • 5.4.1.4 Cycloaddition of Ketenes with Nucleophilic Alkenes. (wiley.com)
  • 5.4.1.5 Cycloaddition of Ketenes with Allenes. (wiley.com)
  • 5.4.3 [4+2] Cycloadditions of Ketenes. (wiley.com)
  • 5.4.4 Intramolecular Cycloadditions of Ketenes. (wiley.com)
  • So in this video I'm going to introduce you guys to another form of cycloaddition called photochemical cycloaddition. (clutchprep.com)
  • So, that is the basics of photochemical cycloaddition, that's you know, that's all you would need to be able to draw the mechanism but how do you know the product is actually favored? (clutchprep.com)
  • In this updated and expanded 1986 edition the authors summarise those classes of reaction that best illustrate the types of photochemical behaviour commonly observed for simple organic molecules. (cambridge.org)
  • Methyl nitrile ylide was generated by both a photochemical and desilylation route and has been characterized by UV spectroscopy and by its kinetic and cycloaddition behavior. (elsevier.com)
  • 5.2 Photochemical Reactions. (wiley.com)
  • The strained σ bond of the cyclopropane was found to play the role of an alkene in a conventional [3+2] dipolar cycloaddition. (ebscohost.com)
  • The cycloaddition reactions of imidazolium-3-dicyanomethanide 1,3-dipoles with electron poor alkene and alkyne dipolarophiles were explored. (nuigalway.ie)
  • In pericyclic and concerted [2 + 2] cycloadditions, the ketene approaches the alkene such that the reaction occurs antarafacially at the ketene and suprafacially at the alkene. (organicreactions.org)
  • Furthermore, a related reaction is described involving the coupling of thio acids and sulfonyl azides leading to the chemoselective formation of amides. (gla.ac.uk)
  • In many instances, the reaction sequence regiospecifically ligates azides and terminal acetylenes to give only 1,4-disubstituted [1,2,3]-triazoles. (freepatentsonline.com)
  • Although thermal dimerization of thymine residues in DNA is forbidden, photochemistry allows the 4-electron cycloaddition. (merlot.org)
  • The classic example is the dimerization of cyclopentadiene, involving two [4+2] Diels-Alder reactions. (comporgchem.com)
  • In this video we're going to dive deep into a type of pericyclic reaction called a thermal cycloaddition. (clutchprep.com)
  • REACTIONS OF OZONE IN WATER Oxidation-Reduction Reactions. (chipsbooks.com)
  • Electrophilic addition reactions of O,O-dialkyldithiophosphoric acids to non-activated a-olefins proceeding in accordance with the Markovnikov's rule were studied. (ebscohost.com)
  • According to the data of the activation energy, we predict that path c would be the major reactive channel of the cycloaddition reactions of singlet dibromocarbene with formaldehyde, which proceeds in three steps and the energy barrier for the key step is 13.7 kJ·mol-1. (pku.edu.cn)
  • Solvent polarity plays a critical role for many heterogeneously catalyzed reactions of oxygenated molecules derived from biomass. (aiche.org)
  • Since strongly bound chelating agents are not always the most effective, achieving optimal rates requires an assessment of the potential donor molecules in the reaction mixture. (scripps.edu)
  • The appeal of developing improved drugs to promote helpful reactions or prevent harmful ones has driven organic chemists to better understand how to synthetically create these molecules and reactions in the laboratory. (news-medical.net)
  • Unexpected differences in stereoselectivity and regioselectivity were observed in some reactions when carried out on solid support. (pnas.org)
  • In agreement with the experimental results, the reaction with methyl vinyl ether proceeds with high endo stereoselectivity and with complete regioselectivity to form the 6-methoxy cycloadduct. (elsevier.com)
  • The cytotoxicity of Cu(I) ions has been greatly reduced due to the use of Cu(I) ligands, which enabled the CuAAC reaction to proceed on the cell surface, as well as within an intracellular environment. (springer.com)
  • In this review, we summarize the development of CuAAC reaction as a prominent bioorthogonal reaction, discuss various ligands used in reducing Cu(I) toxicity while promoting the reaction rate, and illustrate some of its important biological applications. (springer.com)
  • Research work on the aza Diels alder cycloaddition reactions in aqueous systems would be green pathway for organic processes and will definitely protect health as well as environment from toxic materials. (tsijournals.com)
  • Large rate accelerations were observed when the reactions were completed in aqueous acetonitrile rather than pure acetonitrile. (nuigalway.ie)
  • Anl-containing proteins are susceptible to a copper-catalyzed "click" reaction to attach affinity tags for purification or fluorescent tags for visualization. (asm.org)
  • The mechanistic rationale for the reaction suggests tandem cyclizations involving copper-catalyzed cycloaddition and 6-endo carbocyclization reactions. (biomedsearch.com)
  • The reaction centers around an imine - lithium enolate cycloaddition. (wikipedia.org)
  • The electronic structure and the participation of the simplest azomethine imine (AI) in [3+2] cycloaddition (32CA) reactions have been analysed within the Molecular Electron Density Theory (MEDT) using Density Functional Theory (DFT) calculations at the MPWB1K/6-311G(d) level. (mdpi.com)
  • We propose this thermally allowed synchronous reaction mode as an alternative to the Woodward-Hoffmann antarafacial mode or the stepwise biradical pathways normally invoked for such thermally activated cycloadditions. (rsc.org)
  • A formal 3+3 cycloaddition reaction. (wisc.edu)
  • Intramolecular formal oxa- 3+3 cycloaddition approach to the ABD system of phomactin A . Organic Letters. (wisc.edu)
  • In these reactions, the ketene serves primarily as the 2π component. (organicreactions.org)
  • 1.1.2 Theoretical Studies of Ketene Reactions. (wiley.com)
  • In the case of the reaction of the parent nickel enolate complex 1 (which displays an unsubstituted Ni-O=CR)CH2 arrangement) with MVK, a double-addition process has been observed, consisting of two successive cycloaddition/isomerization reactions. (csic.es)
  • Several aspects of (2+2) cycloaddition reactions of tert-butylcyanoketene (TBCK) with different ketenophiles have been studied. (edu.sa)
  • [6] Consumption of the vinylketene via cycloaddition or electrocyclization drives the ring-opening forward. (organicreactions.org)