accomplished by treatment with carboxylic anhydrides, acid chlorides or alkyl chloroformates. The reaction involves a cyclization to 4-imino-3,1-benzothiazinium salts, whose thioimidate structure is trapped by a subsequent reaction with the acyl donor. 2-Ureidobenzonitriles do not undergo such an intermolecular tandem reaction. The different reaction behavior of both types of substrates was verified by
2- thioureidobenzonitriles至4-酰亚
氨基-4-质子催化转化ħ -3,1-苯并
噻嗪是通过用
羧酸酐,酰
氯或
氯甲酸烷基酯来完成的。该反应涉及环化成4-亚
氨基-3,1-苯并
噻嗪鎓盐,其
硫代亚
氨酸酯结构被随后与酰基供体的反应所俘获。2-
脲基
苄腈不进行这样的分子间串联反应。两种类型底物的不同反应行为均通过NMR监测并使用18 O富集
水进行了验证。