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.
A general study on the conjugateaddition of anionic nucleophiles to alkylidenebis(sulfoxides) is presented. Alkoxides gave high yielding and diastereoselectiveaddition reactions, which could be influenced by solvents and the counteranion. Azides provided an interesting entry into sulfinyl‐substituted triazoles. Organometallics, mainly copper reagents, proved also to be valuable nucleophiles, and