AlkylationEnolKetonesReactionsIonsSynthesisStereochemical outcomeReactionHighly nucleophilicLithium enolateAcylKetoneUndergoesProtonKineticEstersConjugateReactiveStereochemistryChemistryAnionCarbonyl compoundPrecursorsEsterAmidesCarbonylsHydrogensElectrophilesResonanceNitrogenCarbonStericMechanismFormSodiumUndergoOrganic
Alkylation6
- Herein, we report an alternative method for alkylation of aromatics via nucleophilic addition of enolates of active methylene compounds to 1,4-dehydrobenzene diradicals derived from enediynes cyclodec-1,5-diyne-3-ene, benzo[3,4]-cyclodec-1,5-diyne-3-ene, and cyclohexeno[3,4]-cyclodec-1,5-diyne-3-ene. (escholarship.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)
- 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)
- 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)
- One is indirect α-alkylation of tropinone, another is the nucleophilic attack from α-C enolate to the nitrogen atom. (usask.ca)
- The most useful reaction of enolate ions is their S N 2 alkylation with alkyl halides. (openstax.org)
Enol10
- Enolates can also be synthesized using alkyl lithium reagents, enol esters, or silyl enol ethers. (thechemistrynotes.com)
- Two electrophiles and two nucleophiles, then, have potential to result in four possible products: Thus, if one wishes to obtain only one of the cross-products, one must control which carbonyl becomes the nucleophilic enol/enolate and which remains in its electrophilic carbonyl form. (micromex.com.pl)
- The α -substitution reaction of a carbonyl compound through either an enol or enolate ion intermediate is one of the four fundamental reaction types in carbonyl-group chemistry. (openstax.org)
- Although enol tautomers are normally present to only a small extent at equilibrium and can't usually be isolated in pure form, they nevertheless contain a highly nucleophilic double bond and react with electrophiles in an α -substitution reaction . (openstax.org)
- An enolate is the deprotonated form of an enol. (mendelset.com)
- It's important that you become familiar with the mechanisms for enol and enolate formation in both acid ( Q738 ) and in base (this problem), as well as carbonyl hydrate formation in both acid ( Q706 ) and base ( Q705 ). (mendelset.com)
- Enol and enolate mechanisms always involve the alpha position of the carbonyl (one away from the carbonyl carbon). (mendelset.com)
- To form an enol (or enolate) from a carbonyl, the alpha position of the carbonyl must be deprotonated, and the double bond (pi electrons) travels 'goes up' to the oxygen to become a lone pair. (mendelset.com)
- To form a carbonyl from an enol (or enolate), the alpha position of the carbonyl must be protonated, and a lone pair on the oxygen 'comes down' to reform the carbonyl. (mendelset.com)
- In enol/enolate mechanisms, new bond formation occurs at the alpha position. (mendelset.com)
Ketones3
- Enolates may be made from carbonyl compounds like aldehydes and ketones by protonating the oxygen atom and then deprotonating the alpha-carbon atom. (thechemistrynotes.com)
- When an enolate interacts with an alkyl halide, alkylated ketones occur. (thechemistrynotes.com)
- Enolates are formed during the deprotonation reaction of carbonyl compounds having a hydrogen atom on α-carbon, such as ketones, certain aldehydes, and esters. (thechemistrynotes.com)
Reactions12
- Nucleophilic acyl substitution describes a class of substitution reactions involving nucleophiles and acyl compounds. (wikipedia.org)
- Because acyl derivatives react with a wide variety of nucleophiles, and because the product can depend on the particular type of acyl derivative and nucleophile involved, nucleophilic acyl substitution reactions can be used to synthesize a variety of different products. (wikipedia.org)
- Both steps are reversible and as a result, nucleophilic acyl substitution reactions are equilibrium processes. (wikipedia.org)
- Because the last step involves the loss of a proton, nucleophilic acyl substitution reactions are considered catalytic in acid. (wikipedia.org)
- While nucleophilic acyl substitution reactions can be base-catalyzed, the reaction will not occur if the leaving group is a stronger base than the nucleophile (i.e. the leaving group must have a higher pKa than the nucleophile). (wikipedia.org)
- The chemical reactivity of 2-pyrrolidinones and 3-pyrrolin-2-ones was evaluated in reactions of addition, nucleophilic substitution, elimination, and reduction as well as the protection of the lactamic nitrogen. (hindawi.com)
- In connection with our studies on the syntheses of potentially bioactive 2-pyrrolidinones and 3-pyrrolin-2-ones [ 1 ], we describe in this paper the results of the performed study on the chemical reactivity of these structural moieties in reactions of addition, nucleophilic substitution, elimination, and reduction as well as the protection of the lactamic nitrogen. (hindawi.com)
- Why are nucleophilic substitution and elimination reactions introduced before electrophilic addition reactions or nucleophilic addition reactions? (teachthemechanism.com)
- Why are nucleophilic addition reactions presented in two chapters (Chapters 18 and 19)? (teachthemechanism.com)
- Similarly, why are nucleophilic addition-elimination reactions presented in two separate chapters (Chapters 22 and 23)? (teachthemechanism.com)
- Recognize and provide curved arrow mechanisms for the following types of organic reactions: electrophilic & nucleophilic aromatic substitution, nucleophilic carbonyl addition, nucleophilic acyl substitution, carbonyl condensation, [4 2] cycloaddition, and substitution ato a carbonyl. (byu.edu)
- This note covers the following topics: Free radical reactions, Electrophilic addition reactions, Electrophilic substitution reactions, Elimination reactions, Nucleophilic addition reactions, Nucleophilic addition / elimination reactions. (freebookcentre.net)
Ions2
- Carboxylate ions are essentially unreactive towards nucleophilic substitution, since they possess no leaving group. (wikipedia.org)
- Alpha hydrogen atoms of carbonyl compounds are weakly acidic and can be removed by strong bases, such as lithium diisopropylamide (LDA), to yield nucleophilic enolate ions. (openstax.org)
Synthesis3
- Seven interesting chiral amines have been synthesized and applied into the enolate chemistry of two interesting precursors of synthesis of natural products: 1,4- cyclohexanedione monoethylene ketal and tropinone.The aldol reaction between the lithium enolate of 1,4-cyclohexanedione monoethylene ketal and benzaldehyde demonstrated the high diastereoselectivity (up to 98% de) and the moderate to high enantioselectivity (up to 75% ee) induced by those chiral lithium amides. (usask.ca)
- Why are the nucleophilic substitution & elimination that are useful for synthesis introduced in two chapters (Chapters 10 and 11) instead of one? (teachthemechanism.com)
- Synthesis of .eta.1 oxygen-bound rhodium enolates. (academicinfluence.com)
Stereochemical outcome1
- 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)
Reaction11
- In this type of reaction, a nucleophile - such as an alcohol, amine, or enolate - displaces the leaving group of an acyl derivative - such as an acid halide, anhydride, or ester. (wikipedia.org)
- When the enolate of an aldehyde or a ketone reacts at the α-carbon with the carbonyl of another molecule under basic or acidic conditions to obtain β-hydroxy aldehyde or ketone, this reaction is called Aldol Reaction. (organic-chemistry.org)
- 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)
- The reaction involves the formation of an enolate intermediate, which then undergoes a nucleophilic attack by the electrophilic benzaldehyde. (syntheticchemicallab.com)
- On the other hand, high diastereoselectivity (up to 100% de) and the low enantioselectivity were obtained from the aldol reaction of tropinone enolate with benzaldehyde differentiated by chiral lithium amides with extra electron donor atoms. (usask.ca)
- A typical modern aldol addition reaction, shown above, might involve the nucleophilic addition of a ketone enolate to an aldehyde. (micromex.com.pl)
- When an alkyl halide is introduced, the enolate ion acts as a nucleophile, and a nucleophilic substitution reaction (specifically, an S N 2 reaction) occurs. (medschoolcoach.com)
- You can also go straight from carbonyl to enolate in one reaction arrow. (mendelset.com)
- 4] These species contain electrophilic centres at the C1 and C3 positions,a nd al atent nucleophilic centre at C2, providing new opportunities for reaction design to target previously inaccessible product architectures. (archive.org)
- 8] Here we report the development of anew general concept for a,b-unsaturated acyl ammonium catalysis.C atalyst turnover is not facilitated by the nucleophilic reaction partner,but by an aryloxide counterion released in situ during the reaction by using an a,b-unsaturated aryl ester as the a,b-unsaturated acyl ammonium precursor (Scheme 1c). (archive.org)
- 1. At which position of pyridine nucleophilic substitution reaction is most preferred? (sanfoundry.com)
Highly nucleophilic1
- Imines are converted into highly nucleophilic aza enolates whenever subjected to treatment with strong bases such as LDA. (thechemistrynotes.com)
Lithium enolate1
- The substance 2 was partially converted to a product identified by 1 H NMR as the thiophenoxylactam 3 , as result of alpha deprotonation of the carbamate of 2 with LDA solution [ 4 ], followed by nucleophilic substitution of the generated lithium enolate with diphenyl disulfide [ 5 ]. (hindawi.com)
Acyl4
- Under acidic conditions, the carbonyl group of the acyl compound 1 is protonated, which activates it towards nucleophilic attack. (wikipedia.org)
- This 'up and down' mechanism is similar to the Nucleophilic Acyl Addition/Substitution mechanisms discussed in problems 705 and 706 , with the difference being that the carbon carbonyl is not where bond formation takes place. (mendelset.com)
- Acyl ammonium and ammonium enolate intermediates have been extensively studied and applied in enantioselective acyl transfer processes and formal cycloadditions,respectively. (archive.org)
- 7] These examples used a,b-unsaturated acid anhydrides or halides as the a,b-unsaturated acyl ammonium precursors.In addition, these methodologies require the reactive partner to contain two distinct nucleophilic functionalities to 1) undergo conjugate addition to the a,b-unsaturated acyl ammonium intermediate,a nd 2) enable turnover of the Lewis base catalyst (Scheme 1b). (archive.org)
Ketone3
- With an unsymmetrically substituted ketone, such a non-nucleophilic, sterically-demanding, strong base will abstract a proton from the least hindered side. (organic-chemistry.org)
- Proton transfer is avoided with lithium enolates at low temperatures in ethereal solvents, so that addition of a second carbonyl partner (ketone or aldehyde) will produce the desired aldol product. (organic-chemistry.org)
- 47. Stereochemistry of the Michael addition of ester and ketone enolates to .alpha. (academicinfluence.com)
Undergoes1
- The zinc enolate thus formed readily undergoes β-fragmentation unless it is trapped by electrophiles in situ. (journaltocs.ac.uk)
Proton1
- If one partner is considerably more acidic than the other, the most acidic proton is abstracted by the base and an enolate is formed at that carbonyl while the carbonyl that is less acidic is not affected by the base. (micromex.com.pl)
Kinetic2
- This process begins with the irreversible generation of the kinetic enolate, e.g. by employing a sterically hindered lithium amide base such as LDA (lithium diisopropylamide). (organic-chemistry.org)
- The alpha hydrogen deprotonated to form the kinetic enolate is less hindered, and therefore deprotonated more quickly. (micromex.com.pl)
Esters1
Conjugate3
- 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)
- 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)
- Conjugate addition of tert-butoxide to 2-aminochalcones provided the corresponding enolates, which underwent Michael addition to another molecule of 2-aminochalcone to afford a dimeric species of 2-aminochalcones. (korea.ac.kr)
Reactive3
- 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)
- Why are enolates more reactive than enols? (thechemistrynotes.com)
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)
Chemistry4
- What is the importance of enolates in organic chemistry? (thechemistrynotes.com)
- Enolates are essential in organic chemistry because they may be utilized to generate a wide range of compounds. (thechemistrynotes.com)
- This opened two new paths to develop tropinone enolate chemistry. (usask.ca)
- Kumagai, N & Shibasaki, M 2016, ' Nucleophilic and Electrophilic Activation of Non-Heteroaromatic Amides in Atom-Economical Asymmetric Catalysis ', Chemistry - A European Journal , vol. 22, no. 43, pp. 15192-15200. (elsevierpure.com)
Anion1
- The interaction of oxygen anion and alkene carbon produces enolates. (thechemistrynotes.com)
Carbonyl compound1
- In aldol condensation , an enolate ion reacts with another carbonyl compound to form a conjugated enone. (khanacademy.org)
Precursors1
- They are the precursors of enolates and many other chemicals. (thechemistrynotes.com)
Ester1
- Sodium ethoxide removes the hydrogen atom attached to the α -carbon of N -phthalimidomalonic ester's two ester groups, forming an enolate. (medschoolcoach.com)
Amides1
- Amides are reluctant to form enolates for nucleophilic addition, and α,β-unsaturated amides exhibit diminished electrophilicity at the β-carbon. (elsevierpure.com)
Carbonyls1
- Enolates are formed from carbonyls under basic conditions. (mendelset.com)
Hydrogens1
- An extension of this effect can allow control over which of the two carbonyl reactants becomes the enolate even if both do have α hydrogens. (micromex.com.pl)
Electrophiles1
- Because an enolate anion's negative charge is delocalized between the -carbon and oxygen, electrophiles can connect to either atom. (thechemistrynotes.com)
Resonance2
- The resonance structure of the enolate ion that places the negative charge on the oxygen is the most stable. (thechemistrynotes.com)
- In the mechanism below the carbonyl was deprotonated at the alpha position, and the enolate was then drawn as a resonance form. (mendelset.com)
Nitrogen1
- Aza enolates are the nitrogen analogs of enolates. (thechemistrynotes.com)
Carbon1
- Nucleophilic rearrangements to carbon involving carbanions, Favorskii. (warwick.ac.uk)
Steric1
- This is because, in some situations, steric hindrance destabilizes the more substituted enolate. (thechemistrynotes.com)
Mechanism1
- House found a mechanism for permitting these enolates to react with aldehydes to make the required aldols. (thechemistrynotes.com)
Form2
- Because of this, methanal (formaldehyde) cannot form enolates. (thechemistrynotes.com)
- The protons are pulled out to form enolates as follows. (micromex.com.pl)
Sodium1
- A novel protocol to synthesize 3,4'-biquinolines from 2-aminochalcones in the presence of a stoichiometric amount of sodium tert-butoxide as the nucleophilic promotor was developed. (korea.ac.kr)
Undergo1
- Enolates of substrates having free N-H bonds undergo protodemetalation to provide ultimately the 1,4-addition adduct. (journaltocs.ac.uk)
Organic1
- Enolates are organic anions that are generated from organic molecules, particularly enols. (thechemistrynotes.com)