We describe herein a new synthesis of enantiopure alkylidene 1,1-bis-p-tolyl-sulfoxides (5), based on a two-steps sequence. The first one involves the alkylation of the lithium anion of the (S,S)-bis-p-tolylsulfinylmethane (1) with aldehydes. The second one consists in a mild dehydration of the sulfinyl alcohols 3 and 4 with the morpho CDI reagent. Some features (reactivity, diastereoselectivity) of the alkylation reaction are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
Highly Diastereoselective Conjugate Addition to Alkylidene Bis(Sulfoxides): Asymmetric Synthesis of (+)-erythro-Roccellic Acid
Thermal elimination of sulfenic acid from enantiopure beta,beta'-disubstituted bis-sulfoxides allows the stereoselective synthesis of enantiopure acyclic beta,beta'-disubstituted vinylsulfoxides. This mild and stereospecific synthesis provides either (E) or (Z) vinylsulfoxides in high yields and is compatible with acid or base sensitive functional groups.