Acid-Catalyzed Conversion of 7-Ethynyl- and 7-Vinylcyclohepta-1,3,5-trienes to Substituted Benzene Derivatives
作者:Shinya Minegishi、Jun Kamada、Ken’ichi Takeuchi、Koichi Komatsu、Toshikazu Kitagawa
DOI:10.1002/ejoc.200300245
日期:2003.9
these cases. Kinetic studies indicated that the rearrangement of 1a is significantly accelerated by the presence of tert-butyl groups on the seven-membered ring. The order of reactivity, 1a < 1b < 1c < 1d, is in agreement with the population of NCD forms at equilibrium, as estimated by the calculated CHT−NCD energy-difference and the 13C NMR chemical shifts of 1a−d, indicating the importance of the equilibrium
研究了在 THF/TFA (5:1, v/v) 中酸催化重排在 C-7 处含有 α,β-不饱和取代基的环庚-1,3,5-三烯。7-Ethynylcyclohepta-1,3,5-triene (1a) 及其 1,4-di-tert-butyl (1b)、1,5-di-tert-butyl (1c) 和 2,5-di-tert丁基 (1d) 衍生物分别异构化为苯基丙二烯 2、3、7 和 3。2,5-二叔丁基-7-乙烯基环庚-1,3,5-三烯(17)得到(E)-和(Z)-1,4-二-叔-的混合物(66:34)丁基-2-(1-丙烯基)苯(20)。提出了一种涉及降卡二烯互变异构体 (NCD) 质子化的机制,NCD 与环庚三烯 (CHT) 1 或 17 处于平衡状态,然后裂解三元环得到铷离子。相比之下,2,5-di-tert-butyl-7-cyanocyclohepta-1,3,5-triene (12)