Enantioselective Generation and Diastereoselective Reactions of Chiral Enolates Derived from α-Heterosubstituted Carboxylic Acids. Preliminary Communication

Dioxolanones 7 and 8a and oxazolinones 9a derived from pivalaldehyde and lactic acid, mandelic acid, and proline, respectively, furnish chiral enolates of type 3 by deprotonation with LDA. Reactions of these enolates with alkyl halides, aldehydes, and ketones (→ 8b, 9b, 11–13) are highly diastereoselective. Thus, the overall enantioselective α-alkylation of chiral, non-racemic α-heterosubstituted carboxylic acids (4 → 6) is realized.