Absolute rate constants determined for 1,2-C and 1,2-H migrations of cyclobutyl-, cyclopentyl-, benzocyclobutenyl- and benzocyclopentenyl-(chloro)- or -(acetoxy)-carbenes reveal that âphenylâ carbon migrations are preferred to alternative 1,2-C shifts due to Ï-electronic effects.
确定的绝对速率常数显示,
环丁基、环戊基、
苯并环丁烯基和苯并
环戊烯基(
氯)或(
醋酸酯)卡宾的1,2-C和1,2-H迁移中,由于π-电子效应,“苯基”碳迁移比其他1,2-C迁移更为优先。