The reaction of 1, 3-dimethyl-5-nitro-6-chlorouracil with 2-aminothiophenol in benzene containing an excess of triethylamine gave 1, 3-dimethyl-10H-pyrimido (5, 4-b) (1, 4) benzothiazine-2, 4 (1H, 3H) dione quantitatively via the Smiles rearrangement. The reaction in acetic acid, however, resulted in the formation of 2-methyl-4-nitropyrimido (4, 3-b) benzothiazoline-1, 3 (2H, 10H)-dione in 78% yield, involving an unusual uracil-ring cleavage which appears to occur in a benzothiazoline intermediate in the course of the acid-catalized Smiles rearrangement.
1, 3-二甲基-5-硝基-6-
氯尿
嘧啶与2-
氨基
苯硫酚在含有过量
三乙胺的苯中反应,得到1, 3-二甲基-10H-
嘧啶基(5, 4-b) (1, 4)苯并
噻嗪-2, 4 (1H, 3H) 二酮通过 Smiles 重排定量。然而,在
乙酸中的反应导致形成 2-甲基-4-
硝基嘧啶基 (4, 3-b)
苯并噻唑啉-1, 3 (2H, 10H)-二酮,产率为 78%,其中涉及不寻常的尿
嘧啶环在酸催化的 Smiles 重排过程中,
苯并噻唑啉中间体似乎发生了裂解。