Sulfonate Versus Sulfonate: Nickel and Palladium Multimetallic Cross-Electrophile Coupling of Aryl Triflates with Aryl Tosylates
作者:Kai Kang、Liangbin Huang、Daniel J. Weix
DOI:10.1021/jacs.0c04670
日期:2020.6.17
While phenols are frequent and convenient aryl sources in cross-coupling, typically as sulfonate esters, the direct cross-Ullmann coupling of two different sulfonate esters is unknown. We report here a general solution to this chal-lenge catalyzed by a combination of Ni and Pd with Zn reductant and LiBr as an additive. The reaction has broad scope, as demonstrated in 33 examples (65% ± 11% ave yield)
虽然苯酚是交叉偶联中常见且方便的芳基来源,通常作为磺酸酯,但两种不同磺酸酯的直接交叉乌尔曼偶联尚不清楚。我们在此报告了针对这一挑战的通用解决方案,该解决方案由 Ni 和 Pd 与 Zn 还原剂和 LiBr 作为添加剂的组合催化。该反应具有广泛的范围,如 33 个实例所示(平均产率 65% ± 11%)。机理研究表明,Pd 强烈偏好三氟甲磺酸芳基酯,Ni 催化剂对甲苯磺酸芳基酯的偏好较小,催化剂之间的芳基转移由 Zn 介导,Pd 通过消耗芳基锌中间体来提高产率。