Regiospecific iodocyclization of S-allyl dithiocarbamates: synthesis of 2-imino-1,3-dithiolane and 2-iminium-1,3-dithiolane derivatives

4-Alkyl-2-imino-1,3-dithiolanes and 4-alkyl-2-iminium-1,3-dithiolanes were prepared in excellent yields with complete regiospecificity under mild conditions by the iodocyclization of S-allyl dithiocarbamates. Dehydrohalogenation of the 4-alkyl-2-imino-1,3-dithiolanes gave 4-alkylidene-2-imino-1,3-dithiolanes in excellent yields.