Competitive acylation of arylstyrylsilanes: Controlling silanucleophile reactivity
作者:Michael A. Brook、Courtney Henry
DOI:10.1016/0040-4020(95)00945-0
日期:1996.1
substitution reactions occurred cleanly between acyl cations and arylstyrylsilanes 2–4. With an unsubstituted aryl group, 2 underwent transfer of the styryl group to form styryl ketone 5 as would be predicted from previous kinetic studies. With increasing methyl group substitution of the aryl group, aryl group transfer occurred competitively such that 3 showed a 2:1 preference for destyrylation: dearylation
酰基阳离子和芳基苯乙烯基硅烷2–4之间完全发生了亲电取代反应。如先前的动力学研究所预测的,对于未取代的芳基,2进行苯乙烯基的转移以形成苯乙烯基酮5。随着芳基甲基取代基的增加,芳基的竞争发生竞争,因此3显示出2:1的去甲苯乙烯基化偏好:脱芳基化得到10:11,而4进行了异戊基的排他性转移,得到异辛基酮6-8。这些结果与非甲硅烷基化化合物的亲电子芳族取代反应不一致。随着芳基甲基取代基的增加,出于电子原因,其反应性应提高,但不应超过苯乙烯基的程度。然而,当甲硅烷基的侧翼为甲基时,通过减轻空间拥塞还额外地促进了硅-芳基键的裂解,使得该过程优先发生于苯乙烯基的转移。