A new functionalized, chiral disulfide derived from L-cysteine: (R,R)-bis[(3-benzyloxazolan-4-yl)-methane] disulfide as a catalyst in the diethylzincaddition to aldehydes

A new, easily accessible, chiral disulfide 3 was prepared from L-cysteine i n a short synthetic sequence (Scheme 1) and applied successfully as a highl y efficient catalyst for the enantioselective addition of diethyl zinc to a romatic and aliphatic aldehydes to afford the product alcohols in up to mor e than 99% ee. In contrast to the more common amino alcohols used in simila r reactions, catalyst 3 does not have a protic hydrogen in the form of a fr ee hydroxy group. (C) 1999 Elsevier Science Ltd. All rights reserved.