Sulphur nitride in organic chemistry. Part 17. Preparation of 1,8-diaminocarbazole

Abstract

Tetrasuiphur tetranitride (1) reacted with 5,5′-di-t-butylbiphenyl-2,2′-diol (3a–d) to give 4-(2-hydroxyphenyl)-2,1,3-benzothiadiazole (4a) and (4c), bi-2,1,3-benzothiadiazol-4-yl (5), and benzofurano[3,2-e]-2,1,3-benzothiadiazole (6), the yields of which were dependent upon the ortho substituent of (3) and an equimolar ratio of (1) : (3). Reduction of compound (5) with SnCl₂in acetic acid-concentrated hydrochloric acid gave the imidazolyl-thiazole (11), while reduction with Sn in concentrated hydrochloric acid gave tetra-aminobiphenyl (9), which was diazotised to give the bitriazolyl (12). Compound (9) when heated in phosphoric acid give 1,8-diaminocarbazole (2)[27% yield from the dibromobiphenyldiol (3c)].