2,4-Dimethyl-7-methylenetetracyclo[3.3.-0.0.2,804,6]octan-3-one and its corresponding alcohol were reacted with TCNE to give π2+π2 cycloadducts at the exomethylene group. On the other hand, 1,5-dimethyl-6-methylenetricyclo[3.2.1.02,7]oct-3-en-8-one did not react with TCNE, whereas its corresponding alcohol and 1,5-dimethyl-6,8-dimethylenetricyclo[3.2.1.02,7]oct-3-ene afforded π2+π2 cycloadducts. The reactivities were correlated with the 13C-NMR data of the exomethylene groups, the electron densities of which are affected by the carbonyl group.
2,4-二甲基-7-亚甲基四环[3.3.-0.0.2,804,6]辛-3-酮及其相应的醇与 TCNE 反应,在外亚甲基处生成 π2+π2 环加载产物。另一方面,1,5-二甲基-6-亚甲基
三环[3.2.1.02,7]辛-3-烯-8-酮不与 TCNE 反应,而其相应的醇和 1,5-二甲基-6,8-二亚甲基
三环[3.2.1.02,7]辛-3-烯则生成了 π2+π2环加载产物。反应活性与外亚甲基的 13C-NMR 数据相关,外亚甲基的电子密度受羰基的影响。