Synthesis and photolysis of azido-benzo[b]thiophens, -benzothiazoles, -benzimidazoles, and -indazoles: novel 6,7-diamino-benzothiazoles, -benzimidazoles, and -indazoles and 6-diethylamino-8H-thiazolo [5,4-c]azepines

Abstract

Irradiation of the 6-azidobenzothiazoles (4)–(9)(see Scheme) in the presence of an excess of a secondary amine gave either the corresponding 6,7-diaminobenzothiazole (14)–(20), a 6-amino-8H-thiazolo[5,4-c]azepine (21)–(24), a mixture of both, or intractable material [as in the case of azide (9)]. Irradiation of 7-azido-3-methylbenzo[b]thiophen in an excess of diethylamine gave 7-amino-3-methylbenzo[b]thiophen and a trace of 3,3′-dimethyl-7,7′-azobenzo[b]thiophen. 6-Azidoindazole gave 7-amino-6-diethylaminoindazole (32) and 5(6)-azidobenzimidazole gave a mixture of 4(7)-amino-5(6)-diethylaminobenzimidazole (33) and 5(6)-amino-4(7)-diethylaminobenzimidazole (34). Photolysis of either 6-azidobenzothiazole or its 2-methyl derivative in a methoxidemethanol–dioxan mixture gave the corresponding 6-methoxy-8H-thiazolo[5,4-c]azepine, (30) or (31), respectively.