3,4-Bis(trimethylsilyl)-1H-pyrrole (5) was employed as a key precursor to generate a highly strained and reactive five-membered cyclic cumulene, namely 1-tert-butoxycarbonyl-3,4-didehydro-1H-pyrrole (4). The transient existence of 4 at room temperature was confirmed by trapping reactions with furan, acrylonitrile, and benzene, affording cycloadducts 13-15. The choice of the electron-withdrawing tert-butoxycarbonyl
3,4-双(三甲基甲
硅烷基)-1H-
吡咯(5)被用作生成高应变反应性五元环状
枯烯的关键前体,即1-叔丁氧基羰基-3,4-二氢-1H-
吡咯(4)。通过捕获与
呋喃,
丙烯腈和苯的反应,确认了4在室温下的瞬时存在,从而提供了13-15的环加合物。选择吸电子的叔丁氧羰基作为N-取代基是至关重要的,因为它能够调节11a和11b的电子密度。结果,分别获得了三
碘tri单
碘鎓12a和12b。相反,N-叔丁基-3,4-双(三甲基甲
硅烷基)-1H-
吡咯(9)在用Zefirov试剂处理后生成
三氟甲磺酸双
硅鎓10。