Vilsmeier-Haack reaction of 2-amino-X-benzothiazoles with N-phenylformamide in the presence of benzenesulfonyl chloride

Abstract

2-Amino-X-benzothiazoles (X = H, 4-Cl, 6-Cl, 6-NO2, 6-CH3, 6-OCH3, 6-Br) react with N-phenylformamide and two equivalents of benzenesulfonyl chloride in pyridine, affording different products in dependence on the substituent X: N-(X-2-benzothiazolyl)formamidines, N-phenyl-N’-(X-2-benzothiazolyl)formamidines, N-phenyl-N’,N’’-bis(X-2-benzothiazolyl)triaminomethanes, N-(X-2-benzothiazolyl)benzenesulfonamides and N-2-((X-3-phenyliminomethyl)-benzothiazolylidene)benzenesulfonamides. In the presence of one equivalent of benzenesulfonyl chloride, benzothiazoles I either do not react or are partially benzenesulfonated.