Unexpected Formation of Benzothiazoles in the Synthesis of New Heterocycles: Benzo-1,2,4-dithiazines

Abstract

The synthesis of benzo-1,2,4-dithiazines was investigated presuming a reversible sulfur-sulfur bond formation. 2-Aminothiophenol, when allowed to react with isothiocyanates, provided benzothiazoles. 2,2′-Diaminodiphenyl disulfide underwent cyclizations very readily without any reducing agent to give, according to the reaction conditions, benzothiazoles or benzo-1,2,4-dithiazines. The developed procedure offers a simple and convenient way to prepare the title compounds in very good to excellent yields. Until now, benzo-1,2,4-dithiazines as well as 2,2′-diaminodiphenyl disulfides bearing aminocarbonothioyl groups were unknown.

Key words

benzo-1,2,4-dithiazines - benzothiazoles - cyclizations - heterocycles - sulfur

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