A FACILE ASYMMETRIC SYNTHESIS OF β-SUBSTITUTED ALKANOIC ACID THE HIGHLY STEREOSELECTIVE MICHAEL ADDITION OF GRIGNARD REAGENTS TO α,β-UNSATURATED CARBOXYLIC AMIDES DERIVED FROM l -EPHEDRINE

The Michael addition of Grignard reagents to chiral α,β-unsaturated carboxylic amides derived from 1-ephedrine affords highly optically active β-substituted alkanoic acids after acid hydrolysis. This high stereoselectivity is explained by considering the formation of rigid internal chelate complexes.