Cycloaddition reactions of substituted cycloheptatrienes with benzyne and quinones: an entry to the substituted benzhomobarrelenes
作者:Abdullah Menzek、Metin Balcı
DOI:10.1016/s0040-4020(01)87191-x
日期:1993.7
Two cycloheptatriene derivatives 8 and 9 react with benzyne to give adducts 10–12 having anti benzhomobarrelene geometry. On the other hand, cycloadditionreactions of benzoquinone and homobenzoquinone 16 with cycloheptarienes 1 and 8 resulted in the exclusive formation of 13, 17 and 18, respectively. The endoconfiguration of benzoquinone ring in 13 was confirmed by photochemical (2+2)-cycloaddition
ketone 25a are secondary products and arise from 21a and 22a. However, hightemperature (77 °C) bromination of compounds 18a and 18b gave only nonrearranged products 19 and 20 whose barrelene skeletons were preserved. It is our conclusion that the low temperature reaction is ionic, where in the hightemperature reaction radical intermediates are involved. The mechanism for the formation of the products