Asymmetric induction reactions. V. The palladium-catalyzed asymmetric .alpha.-allylation of carbonyl compounds with chiral allyl esters via enamines and imines

Abstract

A novel and excellent method for asymmetric α-allylation of carbonyl compounds via their chiral enamines or imines bearing allyl esters has been developed. Readily available chiral allyl esters having chirality at the a-position of the ester carbonyl group, such as (S)-proline and other (S)-α-amino acid allyl esters, have been found to serve as good asymmetric allylating reagents in palladium-catalyzed reactions of the chiral enamines and imines derived from them. The use of (S)-proline or (S)-valine allyl esters as the amino parts in the enamines or imines provided the highest optical yields of the corresponding α-allyl carbonyl compounds. A mechanism for asymmetric induction is proposed based on the stereochemical results obtained