The oxidative cyclization of n ‐phenyl‐3‐methylthiopropylamines to form N ‐phenyl‐s‐methylisothiazolidinium salts

A series of N ‐phenyl‐3‐methylthiopropylamine hydrochlorides were prepared by reacting a series of anilines with methional and sodium cyanoborohydride. These were cyclized upon oxidation by N ‐chloro‐succinimide to the corresponding N ‐phenyl‐S‐methylisothiazolidinium derivatives which were isolated as the tetraphenylborate salts. Compounds successfully prepared included the m ‐methyl, p ‐methyl, m ‐methoxy, and p ‐methoxyphenyl derivatives.