Synthesis of some 5-substituted 2-aminobenzenethiols and their conversion into phenothiazines via Smiles rearrangement

Abstract

An improved and direct method for the preparation of 5-substituted 2-aminobenzenethiols (III; R = Cl, Br, Me, OMe, or NO₂) through hydrolytic cleavage of substituted 2-aminobenzothiazoles (II; R = Cl, Br, Me, OMe, or NO₂) without the necessity for isolating the zinc thiolate intermediate is reported. Some 3-mono- and 3,7-di-substituted phenothiazines have been prepared from these thiols via formation of aryl sulphides and Smiles rearrangement. Some limitations of the Smiles rearrangement under alkaline conditions are discussed. Structures are supported by i.r. and u.v. spectral studies.