regioselectivity of the addition of tert-butyllithium to cinnamic acid is subject to reaction conditions and to substituent electronic effects. Significant effects are observed in the presence of several additives including a radical trap such as α-methylstyrene. Competition experiments by addition of the organolithium reagent to mixtures of substituted cinnamic acids show that the relative rates of both
向
肉桂酸添加
叔丁基锂的区域选择性受反应条件和取代基电子效应的影响。在几种添加剂的存在下观察到了显着的效果,其中包括自由基陷阱,例如α-
甲基苯乙烯。通过向取代的
肉桂酸混合物中添加
有机锂试剂进行竞争实验表明,起始酸的转化率和1,3-加合物的形成的相对速率均受电子效应的影响,而1,4-加成的速率则受到电子效应的影响。不依赖于取代基。这些特征与极性加成机理相一致,但是也可以实现快速
SET平衡,然后进行缓慢的自由基结合。