Studies of Heterocyclic Compounds. VI. The Reactions of 5, 6-Dihydrothiazolo [2, 3-b] thiazolium Salts with O-and S-Nucleophiles

Abstract

The reaction of 5, 6-dihydrothiazolo [2, 3-b] thiazolium salts (1) with hydroxide ion furnished disulfide of 3-(2-mercaptoethyl)-4-thiazolin-2-one (6). The reaction of 1 with hydrogensulfide ion furnished 3-(2-mercaptoethyl)-4-thiazolin-2-thione (7) and/or its disulfide (8) and with N, N-dimethyldithiocarbamate ion furnished 3-(N, N-dimethyl-dithiocarbamylethyl)-4-thiazolin-2-thione (12) whereas the reaction of 1b with thiophenolate ion afforded 3-(2-phenylthioethyl)-4-thiazolin-2-thione (18b), thiazole (21), 6b, phenyl 2-[2-(4-phenylthiazolin-2-thion-3-yl) ethylthio] ethyl disulfide (22) and phenyl 2-phenylthioethyl disulfide (23). Brief reaction mechanism of the formation of these products are discussed. The reaction of 1 is considered to be initiated by the attack of the nucleophile on the polarized >C=N< bond to form an adduct and to proceed through AE-mechanism. The elimination stage of the reaction is concluded to depend upon basicity, polarizability and other properties of the reagent to induce either the cleavage of S₇-C_7a bond, the cleavage of S₇-C_7a and N-C₅ bonds, or another attack of the reagent on C₅ or on S₇.