Selectivity in ketenimine-thioketone cycloadditions. 1. 1,4- and 1,2-Addition pathways and the synthesis of 4H-3,1-benzothiazines, 2-iminothietanes, and thioacrylamides
N-p-Tolyl and N-phenylketenimines (1) react with thiobenzophenones (2) by a formal 4+ 2 cycloaddition to give substituted 4H-3,1-benzothiazines (4) whose structures have been confirmed by an X-ray diffraction study, whereas the N-mesitylketenimine (5) leads to the 2-iminothietan (6) by a 2 + 2 cycloaddition.
N - p-甲苯基和N-苯基酮亚胺(1)通过4 + 2环加成与硫代二苯甲酮(2)反应,生成取代的4 H -3,1-苯并噻嗪(4),其结构已通过X射线衍射证实研究表明,而N-间苯二胺(5)通过2 + 2环加成反应生成2-亚氨基噻吨(6)。
DONDONI A.; BATTAGLIA A.; GIORGIOANNI P., J. ORG. CHEM., 1980, 45, NO 19, 3766-3773