Experimental Evidence Supporting a CuIII Intermediate in Cross-Coupling Reactions of Allylic Esters with Diallylcuprate Species
作者:A. Sofia E. Karlström、Jan-E. Bäckvall
DOI:10.1002/1521-3765(20010504)7:9<1981::aid-chem1981>3.0.co;2-c
日期:2001.5.4
The reaction between an allylic ester and a magnesium diallylcuprate, or an allylic Grignard reagent in combination with a catalytic amount of a copper salt, has been studied. These reactions yield a mixture of homo- and cross-coupled 1,5-diene products. The product ratios obtained are close to those expected for a reaction proceeding via a triallylcopper(III) intermediate consisting of three equivalent
已经研究了烯丙基酯与二烯丙基铜酸镁或烯丙基格氏试剂与催化量的铜盐组合之间的反应。这些反应产生均-和交叉偶联的 1,5-二烯产物的混合物。获得的产物比率接近于通过三烯丙基铜 (III) 中间体进行的反应所预期的那些,该中间体由三个与铜结合的等效烯丙基基团组成。当反应用化学计量量的预先形成的二烯丙基铜酸盐进行时,观察到比对 CuIII 中间体预测的更大的均偶联/交叉偶联比。然而,在稀释时,这个比率会降低并接近预测的比率。与预测的均偶联/交叉偶联比的偏差是由烯烃诱导的均偶联引起的,如对照实验所示。烯丙基配体以 eta3 或 eta1 方式与金属中心配位的可能性为中间体 CuIII 物质的稳定化提供了机会。