Synthesis of 2-Dialkylamino-1,3-oxathioran-2-ylium Salts

Five-Membered ring's trihetero-substituted carbonium salt, 2-dialkylamino-1,3-oxathioran-2-ylium perchlorates [3a-p] were easily prepared from the reaction of N, N-dialkyl-dithiocarbamates [1] with epoxides [2] followed by addition of perchloric acid. 2-Imino-1,3-oxathioran derivatives [4] were obtained by treatment of hygroscopic 2-monoalkylamino-1,3-oxathioran-2-ylium perchlorates with aqueous alkali solution. And then, the reaction of [4] with alkyl iodides gave 2-dialkylamino-1,3-oxathioran-2-ylium iodides [3q&acd