Synthesis of cyclic sulfides and allylic sulfides by phenylsulfanyl (PhS-) migration of β-hydroxy sulfides

Abstract

New routes to cyclic and spirocyclic sulfides involve aldol reactions of dithioesters or chemoselective Mitsunobu reactions of 1,n-diols to give 2-hydroxyalkyl sulfides with a terminal SH group. Treatment with acid gives unrearranged cyclic sulfides, or by rearrangement with PhS-migration, spirocyclic thiolanes and allylic sulfides in almost quantitative yield. We comment on the effect of the chain length on the mode of cyclisation and on the surprising differences between an OH group and an SH group as nucleophile towards an episulfonium ion.