A new class of recoverable chiral sulphoxide: Application to the asymmetric synthesis of β-hydroxy esters.

Abstract

Enantiomerically pure cyclic sulphinadime S (S)R-(+)- 2 was prepared from homochiral sulphinic acid R-(−)- 1 and subsequently converted to the ester S (S)R-(−)- 3 via ring opening with an ester enolate. Aldol reactions of S (S)R-(−)- 3 with aromatic aldehydes gave, with one exception, aldol products 4 in high diastereoisomeric excess. Reductive cleavage of the aldol adducts 4 gave β-hydroxy esters 5 in high (>95%) enantiomeric excess, and thiol 6 which may be recycled to S (S)R-(+)- 2. Thus S (S)R-(+)- 2 represents a source of recoverable chiral sulphoxide.