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Alkylation of enolates and related species

Enolates and related species (enamines, metalated imines, hydrazones, nitronates and the anions of 1,3-dicarbonyl compounds) are carbon nucleophiles. Their alkylation with alkyl halides is one of the most important methods for forming C–C bonds.

This topic deals with how they are generated, how the carbon at which they react is controlled (regioselectivity) and how alkylation can be made to give a single stereoisomer.

Equilibrium between acetone and its enolate in the presence of a base

Enolization and enolate ions

 Alkylation of a carbonyl compound at the alpha carbon with LDA and an alkyl halide

Alkylation of ketones and carboxylic acid derivatives

 2-Methylcyclohexanone gives the less substituted enolate with LDA at minus 78 degrees

Regioselectivity and enantioselectivity in ketone alkylation

 Cyclohexanone, its pyrrolidine enamine and the alkylated ketone

Enamines, imines and hydrazones

 Henry reaction of a nitroalkane with an aldehyde

Nitronate and related anions

 Deconjugative alkylation of cyclohex-2-enone

Enolates of α,β-unsaturated ketones

 Alkylation of acetylacetone at the gamma carbon through the dianion

γ-Alkylation of 1,3-dicarbonyl compounds

 Malonic synthesis: from diethyl malonate to a carboxylic acid

Malonic and acetoacetic syntheses