TaCl5-catalyzed carbomagnesiation of some norbornenes with ethyl Grignard reagents
作者:Rifkat M. Sultanov、Ruslan R. Ismagilov、Natal'ya R. Popod'ko、Artur R. Tulyabaev、Denis Sh. Sabirov、Usein M. Dzhemilev
DOI:10.1016/j.jorganchem.2013.07.017
日期:2013.11
The stereoselective carbomagnesiation reaction of bicyclo[2.2.1]hept-2-ene, endo-tricyclo[5.2.1.02,6]deca-3,8-diene, and exo–endo-5-methylbicyclo[2.1.1]hept-2-ene with EtMgX, where X = Cl or Et, occurs in the presence of catalytic amounts of TaCl5 to give chloro- and ethyl[2-exo-(2′-norbornylethyl)]magnesiums in high yields. The multistep reaction mechanism involving norbornene and ethylene through
双环[2.2.1]庚-2-烯,内-三环[5.2.1.0 2,6 ] deca-3,8-二烯和外-内-5-甲基双环[2.1.1]庚烷的立体选择性碳还原反应具有Xt Cl或Et的EtMgX的-2-烯在催化量的TaCl 5的存在下发生,从而以高收率得到氯和乙基[2- exo -((2'-降冰片基乙基)]]镁。还假定了涉及降冰片烯和乙烯通过塔拉他环戊烷作为关键中间体的多步反应机理。DFT计算证实了所得exo产品的热力学偏好。