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ReactiveSynthesisKetoneAnionAlkylationReactionsReactivityReaction intermediatesEnolsOrganicStereochemistryAldehydes and KetonesConjugate baseAmideAldolEstersAlkyl halideCompoundsNucleophilicFormationNucleophilesThermodynamicallyStabilityReactStableRhodiumImineZirconiumKetoAldehydeMoleculeGenerateChemistryEquilibriumAcidFormPurificationChemicalsTypicallyStabilizesTransitionBasesMechanism
Reactive12
  • The base does two things - it forms the reactive aryne intermediate, and it forms the proximal enolate by deprotonation. (organic-chemistry.org)
  • The reaction directly couples readily available ketone pronucleophiles with allylic alcohols using facile retro-Claisen cleavage to form reactive intermediates in situ. (ku.edu)
  • These issues can determine the relative stability of short-lived reactive intermediates, which usually directly determine the path of the reaction. (conceptdraw.com)
  • Enolates are important organic reactive intermediates. (psiberg.com)
  • Enols are alkenes with an alcohol group whereas enolate is a negatively charged reactive intermediate. (psiberg.com)
  • Enolates have an essential role as organic reactive intermediates. (thechemistrynotes.com)
  • Enolates, the most reactive of the three enols, enolates, and enamines, are the most difficult to separate and store. (thechemistrynotes.com)
  • Enolates are more reactive than enols because they are conjugate bases of enols, and conjugate bases are always significantly greater nucleophiles than acids themselves. (thechemistrynotes.com)
  • Why are enolates more reactive than enols? (thechemistrynotes.com)
  • An electrophile is then added rapidly to ensure that the reactive enolate ion is quenched quickly. (openstax.org)
  • However, steering the reaction course of photo- and/or electrochemically generated reactive intermediates in a stereocontrolled and catalytic fashion is very challenging. (uni-marburg.de)
  • All reactive intermediates remain bound to the chiral catalyst thereby providing a robust catalytic scheme (no exclusion of air necessary) with excellent stereoinduction. (uni-marburg.de)
Synthesis6
  • It was shown that these compounds could be readily transformed into useful intermediates for the synthesis of functionalized, stereochemically defined tetrasub-stituted alkenes (87) and tricyclic dienes of general structure (322A). (ubc.ca)
  • These latter compounds served as useful intermediates for the synthesis of functionalized, stereochemically defined tetrasubstituted alkenes (87). (ubc.ca)
  • The synthesis of enolate is an acid-base reaction. (psiberg.com)
  • The invention further includes novel intermediate compounds useful for the synthesis of asymmetric benzoxanthene compounds having the general structure where substituents R3-R7 correspond to like-referenced substituents in the structure of described above, and Y2 is hydroxyl or amine. (justia.com)
  • Synthesis of .eta.1 oxygen-bound rhodium enolates. (academicinfluence.com)
  • This provides a unique, convergent, regiospecific and possibly stereospecific synthesis of enolates - key intermediates in organic synthesis. (ukri.org)
Ketone8
  • Herein we present the development of asymmetric deacylative allylation of ketone enolates. (ku.edu)
  • For example, an unsymmetrical ketone such as 2-methyl cyclohexanone can form two possible enolates. (psiberg.com)
  • Proton exchange between the original enolate and the alkylated ketone, followed by the alkylation of that enolate ion, may result in numerous alkylations. (thechemistrynotes.com)
  • Hexanophenone (C6H5COC6H5) is an aromatic ketone that is widely used as a synthetic intermediate in the production of a variety of chemicals and materials. (syntheticchemicallab.com)
  • 47. Stereochemistry of the Michael addition of ester and ketone enolates to .alpha. (academicinfluence.com)
  • In a ketone alkylation reaction, for instance, we might use 1 equivalent of lithium diisopropylamide (LDA) in tetrahydrofuran solution at -78 °C. Rapid and complete generation of the ketone enolate ion would occur, and no unreacted ketone would remain, meaning that no condensation reaction could take place. (openstax.org)
  • d-phenylalkylbenzyl carbinol by the reaction of a phenylbenzyl ketone with an alkali metal enolate of an amide to form an aldol adduct, which is reduced and purified to form an .alpha. (everypatent.com)
  • comprising reacting a ketone of the formula, ##STR18## with an alkali metal enolate of an amide of the formula, ##STR19## and M is an alkali metal, to to form the aldol reaction product. (everypatent.com)
Anion5
  • When the enolate anion of compounds (203) was successively treated with HMPA and compound (308) the esters (311) were obtained. (ubc.ca)
  • Similarly, alkylation of the enolate anion of compounds (203) with (325) (which was readily obtained from (203), in which n - 1), followed by the Pd(0)-catalyzed coupling of the resulting alkylated material afforded the tricyclic diene esters (322A). (ubc.ca)
  • The interaction of oxygen anion and alkene carbon produces enolates. (thechemistrynotes.com)
  • rather, the enolate anion abstracts a proton from water and, in doing so, supplies the hydroxyl for deacylation. (inrae.fr)
  • The (chloro)hydroboryl anion reduction intermediate was successfully isolated using a crown ether. (uni-wuerzburg.de)
Alkylation3
  • By combining an initial acylation, alkylation, or glycosylation step with an amine-mediated glycosylation of the boronic ester, a variety of selectively protected di- and trisaccharide derivatives can be accessed in an operationally simple fashion without purification of intermediates. (acs.org)
  • Treatment of the (E) isomers (277) with n-butyllithium at -98°C, followed by alkylation of the resultant nucleophilic intermediate afforded the corresponding trisubstituted vinylgermanes (293). (ubc.ca)
  • When we generate an enolate ion with the intention of carrying out an α alkylation, how can we be sure that a carbonyl condensation reaction won't occur instead? (openstax.org)
Reactions7
  • Surprisingly, the residues forming this cation-binding site and most of their interaction partners are shared with three other TIM barrel enzymes that catalyze diverse carbon-carbon bond cleavage reactions believed to proceed through enolate intermediates (4-hydroxy-2-ketovalerate aldolase, 2-isopropylmalate synthase, and transcarboxylase 5S). (rcsb.org)
  • Alpha-substitution reactions occur at the position next to the carbonyl group, the α-position, and involve the substitution of an α hydrogen atom by an electrophile, E, through either an enol or enolate ion intermediate. (conceptdraw.com)
  • These intermediates can subsequently be employed in many reactions, such as the Aldol and Michael reactions. (thechemistrynotes.com)
  • In this context, electronic absorption spectroscopy has proven itself as a valuable method for the identification of intermediates in ThDP-catalyzed reactions, thereby rationalizing proposed mechanisms. (uni-goettingen.de)
  • Two of the four general carbonyl-group reactions-carbonyl condensations and α substitutions-take place under basic conditions and involve enolate-ion intermediates. (openstax.org)
  • Alpha-substitution reactions require a full equivalent of strong base and are normally carried out so that the carbonyl compound is rapidly and completely converted into its enolate ion at a low temperature. (openstax.org)
  • On the other hand, carbonyl condensation reactions require only a catalytic amount of a relatively weak base, rather than a full equivalent, so that a small amount of enolate ion is generated in the presence of unreacted carbonyl compound. (openstax.org)
Reactivity4
  • Notably, in terms of structural effects on the reactivity and stability of sulfur ylide-like intermediates, 2-pyridyl substituted compound 7a exhibited superior properties over those of others. (beilstein-journals.org)
  • The new information gathered from the studies of ThDP and the aforementioned intermediates is a key contribution to understanding their reactivity. (uni-goettingen.de)
  • The intrinsic reactivity of indole and enolates leads to the formation of C-C bonds to form indole-carvone intermediates. (alfachemic.com)
  • The purpose of this course entitled Structure, Stereochemistry and Reactivity of Organic Compounds and Intermediates: A Problem-solving Approach is to provide a solid foundation on organic chemistry through a problem solving technique which centers on structure, stereochemistry and a mechanistic approach. (freevideolectures.com)
Reaction intermediates2
  • They are also known as alkenols and are commonly discovered as reaction intermediates in organic chemistry. (thechemistrynotes.com)
  • Whilst much has been written about this reaction, relatively little characterisation has been carried out on the reaction intermediates. (exeter.ac.uk)
Enols2
  • Enolates are organic anions that are generated from organic molecules, particularly enols. (thechemistrynotes.com)
  • Enolates are more flexible and are better nucleophiles than enols due to their negative charges. (thechemistrynotes.com)
Organic4
Stereochemistry2
  • Enolates can be used to form new bonds, activate or deactivate atom groups, and change the stereochemistry of a molecule. (thechemistrynotes.com)
  • 46. Stereochemistry of the Michael addition of N,N-disubstituted amide and thioamide enolates to .alpha. (academicinfluence.com)
Aldehydes and Ketones2
Conjugate base2
  • Enolate is the conjugate base. (psiberg.com)
  • Hydrogens, in particular, are mildly acidic because the conjugate base, known as an enolate, is stabilized through conjugation with the orbitals of the carbonyl. (thechemistrynotes.com)
Amide3
  • Unlike the proteases, DLH seems to protonate the incipient leaving group only after the collapse of the first tetrahedral intermediate, rendering DLH incapable of hydrolyzing amide analogues of its ester substrate. (inrae.fr)
  • 3. The method of claim 1 wherein the alkali metal enolate of the amide is selected from the group consisting of 2-lithium-N,N-dimethyl propionamide, 2-sodium-N,N-diethyl propionamide, 2-lithium-dipropyl butyramide and 2-sodium-N,N-dimethylpentamide. (everypatent.com)
  • 6. The method of claim 4 wherein the alkali metal enolate of the amide is selected from the group consisting of 2-lithium-N,N-dimethylacetamide and 2-lithium-N,N-diisopropyl acetamide. (everypatent.com)
Aldol1
  • Can I stop the aldol reaction from happening after enolate forms? (psiberg.com)
Esters2
Alkyl halide2
Compounds2
  • When there are two sites for the proton abstraction in the carbonyl compounds, then two different enolate products are formed. (psiberg.com)
  • In another aspect the invention includes methods for synthesizing the above dye compounds and intermediates. (justia.com)
Nucleophilic3
  • It was found that treatment of alkyl (E)- and (Z)-2,3-bis(tri-methylstannyl)-2-alkenoates with methyllithium at low temperature, followed by reaction of the resultant nucleophilic intermediate with a variety of alkylating agents, afforded the trisubstituted vinylstannanes (80). (ubc.ca)
  • Imines are converted into highly nucleophilic aza enolates whenever subjected to treatment with strong bases such as LDA. (thechemistrynotes.com)
  • The reaction involves the formation of an enolate intermediate, which then undergoes a nucleophilic attack by the electrophilic benzaldehyde. (syntheticchemicallab.com)
Formation7
  • The mechanism for this reaction is based on the formation of a sulfur ylide-like intermediate. (beilstein-journals.org)
  • The halogenation is a typical α-substitution reaction that proceeds by acid catalyzed formation of an enol intermediate. (conceptdraw.com)
  • There are the following factors that favor the formation of kinetic enolates, such as aprotic solvents such as THF can be used to prepare kinetically stable enolates. (psiberg.com)
  • Because the stereochemical outcome of an enolate reaction is often influenced by the geometry of the enolate, enolate formation is a critical stage in many bond-forming processes. (thechemistrynotes.com)
  • ce{H_a}$ and $\ce{H_d}$ proton abstractions resulted the formation of intermediates $\bf{I}$ and $\bf{II}$ , which would abstract from a proton from water to give the corresponding aldols. (stackexchange.com)
  • On the other hand, although abstractions of $\ce{H_b}$ and $\ce{H_c}$ protons are possible and in fast equilibrium, the formation of intermediates $\bf{III}$ and $\bf{IV}$ are very minute depending on the corresponding activation energies. (stackexchange.com)
  • Like the cysteine/serine proteases, DLH has a catalytic triad (Cys-123, His-202, Asp-171) and its mechanism probably involves the formation of covalently bound acyl intermediate via a tetrahedral intermediate. (inrae.fr)
Nucleophiles2
Thermodynamically1
  • To prepare the thermodynamically stable enolate, it is recommended to use protic solvents such as alcohol because the weak base can generate strong conjugate acid which increases the yield. (psiberg.com)
Stability2
React2
  • House found a mechanism for permitting these enolates to react with aldehydes to make the required aldols. (thechemistrynotes.com)
  • Cp * 2 Zr(H)CH 2 CHMe 2 has been shown to react cleanly with CO to form the enolate hydride Cp * 2 Zr(H)OCH=CHCHMe 2 . (caltech.edu)
Stable4
  • Therefore, the more substituted enolate is more stable. (psiberg.com)
  • However, sometimes the more substituted enolate is not a thermodynamic more stable enolate. (psiberg.com)
  • As a result, the more replaced an enolate is, the more stable it is. (thechemistrynotes.com)
  • The resonance structure of the enolate ion that places the negative charge on the oxygen is the most stable. (thechemistrynotes.com)
Rhodium1
  • Specifically, employing Hantzsch ester as photoredox mediator, rhodium bound β-enolate carbon-centered radicals are generated by a selective photoinduced single electron reduction and then trapped by allyl sulfones in a highly stereocontrolled fashion, providing radical allylation products with up to 97% ee. (uni-marburg.de)
Imine1
  • It catalyzes the cis-dehydration of 3-Dehydroquinate via a covalent imine intermediate. (wikipedia.org)
Zirconium1
  • Insertion of metallated epoxides, followed by elimination of zirconium oxide, provide access to a complementary range of alkenes.Insertion of metallated sulphonyl epoxides into organozirconium species forms zirconated epoxides which rearrange to zirconium enolates. (ukri.org)
Keto4
  • Both the keto and enolate states of this intermediate are assigned to a common band in the UV-vis spectra. (uni-goettingen.de)
  • We show that enzymatic reaction proceeds in three chemical steps via UDP-4-keto-D-glucuronic acid and UDP-4-keto-pentose intermediates. (ox.ac.uk)
  • The protonated side chain of Tyr(147) stabilizes the enolate of decarboxylated C(4) keto species ((2)H(1) half-chair) that is then protonated from the Si face at C(5), involving water coordinated by Glu(120). (ox.ac.uk)
  • Arg(277), which is positioned by a salt-link interaction with Glu(120), closes up the catalytic site and prevents release of the UDP-4-keto-pentose and NADH intermediates. (ox.ac.uk)
Aldehyde1
  • NaBH4 is added to reduce the intermediate aldehyde. (sfd.pl)
Molecule1
  • Effectively mimicking how enzymes work, the amine binds to the pyruvate to make an intermediate molecule. (chemical.report)
Generate1
  • Firstly LDA is used to generate the enolate ion (as discussed above). (psiberg.com)
Chemistry1
Equilibrium1
  • A proton transfer equilibrium from the intermediate to a histidine residue is proposed which connects the two limits of the observed band. (uni-goettingen.de)
Acid3
  • Is enolate an acid? (psiberg.com)
  • The production of enolate is an acid-base process. (thechemistrynotes.com)
  • The transitional reaction intermediate named ortho-hydroxycinnamic acid affords the target product via a spontaneous lactonization [19]. (jmchemsci.com)
Form4
  • Attack of the O-enolate to form an ether was a competing reaction in what wasn't the highest yielding process, limiting the team to a 33% overall yield - but yet again, this a was an impressive step-forward. (organic-chemistry.org)
  • What bases form enolates? (psiberg.com)
  • Because of this, methanal (formaldehyde) cannot form enolates. (thechemistrynotes.com)
  • In Chapter 1, tertiary phosphines undergo conjugate additions to activated carbon-carbon multiple bonds to form β-phosphonium enolates, β-phosphonium dienolates, β-phosphonium enoates, and vinyl phosphonium ylides as intermediates. (escholarship.org)
Purification1
  • This allows the purification of the intermediate by recrystallization of the sodium salt. (sfd.pl)
Chemicals1
Typically1
  • Typically enolates are synthesized by using LDA (lithium diisopropylamide). (psiberg.com)
Stabilizes1
  • The Asp ligates the divalent cation, while the Arg probably stabilizes charge accumulation in the enolate intermediate, and the Glu maintains the precise structural alignment of the Asp and Arg. (rcsb.org)
Transition1
  • The stepwise course of any given reaction mechanism can be represented using arrow pushing techniques in which curved arrows are used to track the movement of electrons as starting materials transition through intermediates to final products. (conceptdraw.com)
Bases1
  • Weak bases like alcohol have the tendency to make enolates. (psiberg.com)
Mechanism2
  • Both 3-Dehydroquinate and 3-Dehydroshikimate are intermediates in the reaction mechanism. (wikipedia.org)
  • The second intermediate of particular interest has been 1,2-dihydroxyethyl-ThDP, which was previously identified with a key role in the TK enzyme mechanism. (uni-goettingen.de)