Asymmetric conjugate addition of organometallic reagents in the presence of tertiary amines to chiral α,β-unsaturated amido carboxylic acids. Addition order of reagents as an unprecedented factor in the determination of the sense of asymmetric induction

Abstract

Optically active 3-substituted carboxylic acids have been obtained in moderate enantiomeric excesses (e.e.) by asymmetric conjugate addition of alkyl-lithium, in the presence of tertiary amines, to chiral α,β-unsaturated amido carboxylic acids derived from (S)-proline. The presence of tertiary amine is effective in increasing both the synthetic yields and the e.e.'s. A change in the addition order of tertiary amine and alkyl-lithium to the amido-carboxylic acid changes the sense of asymmetric induction.