N-(2-Phenylethene-1-sulfonyl)-N′-monoalkyl S-methylisothioureas, 2, were ring-closed to yield Michael cycloadducts, 3-methylthio-4-alkyl-5-phenyl-1,1-dioxo-5,6-dihydro-1,2,4-thiadiazines, 3. Bulky N′-alkyl groups hindered the cycloaddition. The base-catalyzed hydrolysis of 3 and 3-chloro-derivatives 4 gave 4-methyl-5-phenyl-2,3,5,6-tetrahydro-1,1,3-trioxo-1,2,4-thiadiazines, 5, which in turn underwent N-alkylation to give 6. The reaction of 4 with amines or with sodium methoxide yielded 3-amino-, 7, or 3-methoxy-thiadiazine derivatives, 9.
N-(2-苯基
乙烯-1-磺酰基)-N′-单烷基 S-甲基异
硫脲 2 环合生成迈克尔环加成物 3-甲
硫基-4-烷基-5-苯基-1,1-二氧代-5,6-二氢-1,2,4-噻二嗪 3。在碱催化下,3 和 3-Cloro-derivatives 4 发生
水解,得到 4-甲基-5-苯基-2,3,5,6-四氢-1,1,3-三氧代-1,2,4-噻二嗪类化合物 5。4 与胺或
甲醇钠反应,可得到 3-
氨基噻二嗪衍
生物 7 或 3-甲氧基噻二嗪衍
生物 9。