A new method for the formation of cyclic ethers and lactones is described. Dimethyl(methylthio)sulfonium fluoroborate (DMTSF) initiates formation of an episulfonium ion, which is followed by internal nucleophilic displacement to give the products in good yields. ... We wish to thank Professor KC Nicolaou for a generous sample of compound 3. ... Okuma K. , Yasuda T. , Takeshita I. , Shioji K. , Yokomori Y. ... Bird P. , Eames J. , Fallis ...
