Studies on 1, 3-Dithiolium Cations. I. A Novel Synthetic Method of 4-p-Substituted Phenyl Derivatives and Related Compounds

A convenient method for the preparation of 4-p-substituted phenyl-1, 3-dithiolium salts was presented. 4-p-Substituted phenacyl N, N-dialkylaminocarbodithioates easily obtained from the reaction of N, N-dialkylamine N, N-dialkylaminocarbodithioates and p-substituted phenacylbromides were cyclized to give 2-immonium 1, 3-dithiole salts. Reduction of immonium salts was performed by the action of NaBH4 to give 2-amino-1, 3-dithiole and the action of acid to this amine gave 1, 3-dithiolium salts immediately. The yield of each step was very high and the operation was simple, giving pure 1, 3-dithiolium salts. The properties of intermediates and 4-p-substituted phenyl-1, 3-dithiolium salts were described.