Chapter 1: Alkylation of Enolates and Carbon Nucleophiles

The chapter emphasizes the critical role of kinetic versus thermodynamic control in forming specific enolate isomers and how these intermediates participate in bimolecular nucleophilic substitution reactions with alkyl halides and other electrophilic coupling partners. Beyond simple enolates, the text explores stabilized carbon nucleophiles including imine anions and enamines as alternative carbon-centered nucleophiles capable of productive alkylation reactions. Dianion chemistry is introduced as a strategy for achieving regioselective alkylation in polyketone systems and other polycarbonyl compounds through sequential deprotonation. Intramolecular alkylation processes receive particular attention, illustrating how ring closure via enolate nucleophilicity enables the construction of five- and six-membered rings and larger cycles through properly designed precursors. The chapter extensively covers stereochemical aspects of alkylation, including diastereoselective reactions in acyclic systems through chelation control and in cyclic systems through inherent ring geometry, as well as enantioselective alkylation using chiral auxiliaries and auxiliary-based enolate modifications. Alternative enolate precursors such as silyl enol ethers, enol acetates, and α,β-unsaturated carbonyl compounds are presented with their respective advantages and limitations. Throughout, practical synthetic applications demonstrate how these alkylation principles combine to construct complex natural products and pharmaceutically relevant structures, establishing the conceptual framework necessary for planning efficient carbon-carbon bond disconnections in retrosynthetic analysis.