Reactions of Sulfanyl Chlorides with Thiocamphor and Thiofenchone: Wagner-Meerwein Rearrangement of an Intermediate Thiocarbonylium Ion

Abstract

The reaction of sulfanyl and disulfanyl chlorides with thiocamphor (6) in the presence of Et3N leads to unsymmetrical di- and trisulfanes, respectively (Schemes 2 and 4). A reaction mechanism via a thiocarbonylium ion, which is immediately deprotonated, is proposed. The formation of a minor product 10 in the absence of a base, resulting from a Wagner-Meerwein rearrangement, is an additional evidence for the intermediacy of a thiocarbonylium ion (Scheme 3). On the other hand, the non-enolizable thiofenchone (13) reacts with sulfanyl chlorides in CH2Cl2/Et3N to give exclusively products with a rearranged bicyclic skeleton (Scheme5). A Wagner-Meerwein rearrangement of the intermediate thiocarbonylium ion is the key step. The structures of the products 10 and 14, which have rearranged bicyclic systems, have been established by X-ray crystallography.