Abstract
Naphtho[2, 3-d]thiazole-4, 9-diones having a substituent in the benzene ring, which were expected to have interesting physiological activities or dyeing properties, were synthesized. Chloronaphtho[2, 3-d]thiazole-4, 9-diones were obtained by amination of 2, 3, 5- and 2, 3, 6-trichloro-1, 4-naphthoquinones followed by ring-closure reaction. Nitration of nap. htho[2, 3-d]thiazole-4, 9-dione in fumic nitric acid-sulfuric acid at 50°C afforded four mononitro compounds: 8-nitro(a major product), 5-nitro, 6-nitro, and 7-nitro derivatives. The structures of 5-nitro and 8-nitro derivatives were determined by deriving the m to the corresponding chloro derivatives. The effects of substituent and thiazole ring in naphtho[2, 3-d]ithiazole-4, 9-diones on the reaction and properties were discussed.
