The thermolysis of the 3-substituted 3H-1, 2-benzodiazepines (1) afforded 1 : 1 mixtures of trans- (2) and cis- (3) 3-vinylindazoles, whereas their photolysis gave only the transisomers (2). The 3-substituted 5-methyl-3H-1, 2-benzodiazepines (4) gave similar results. These findings suggest that the thermolysis occurs in a stepwise manner via the diradical intermediate (9), whereas the photolysis proceeds in a concerted manner.
3-取代的3H-1,2-苯二氮卓类(1)的热解提供反式-(2)和顺式-(3)3-
乙烯基吲唑的1:1混合物,而它们的光解仅提供反式异构体(2)。 3-取代的5-甲基-3H-1, 2-苯二氮卓类化合物(4) 给出了类似的结果。这些发现表明热解作用通过双自由基中间体 (9) 逐步发生,而光解作用以协调的方式进行。