Reactions of some N-(2,5-dimethoxyaryl)thiobenzamides: en route to an analogue of kuanoniamine A

Abstract

Nitration of 2-aryl-4,7-dimethoxybenzothiazoles 7a–7c produces a mixture of 5- and 6-nitrobenzothiazoles which were distinguished by synthesis of the 2-aryl-4,7-dimethoxy-6-nitrobenzothiaoles 12a–12c by oxidative cyclization of the corresponding nitrothiobenzanilides. Reaction of N-[2,5-dimethoxy-4-(p-tolylsulfonylamino)phenyl]thiobenzamide 17d with base to give 5-methoxy-2-phenyl-6-(p-tolylsulfonylamino)benzothiazole 18 with apparent intramolecular replacement of a methoxy group is also described.