Combined Experimental and Computational Mechanistic Investigation of the Palladium-Catalyzed Decarboxylative Cross-Coupling of Sodium Benzoates with Chloroarenes
Combined Experimental and Computational Mechanistic Investigation of the Palladium-Catalyzed Decarboxylative Cross-Coupling of Sodium Benzoates with Chloroarenes
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DOI：
10.1021/acs.joc.1c00910
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发表时间：
2021-08-02
影响因子：
3.6
通讯作者：
Topczewski, Joseph J.
中科院分区：
文献类型：
--
作者：
Humke, Jenna N.;Daley, Ryan A.;Topczewski, Joseph J.
本文对钯催化的苯甲酸钠和氯代芳烃的脱羧基交叉偶联反应进行了机理研究。该反应在Pd中为一级反应。对氯代芳烃的取代基效应最小，对氯代芳烃的反应为零级反应。基于Eyring图和密度泛函理论计算，将钯介导的脱羧基指定为周转限制步骤。催化剂的性能因亲水性的不同而不同，这可以用催化剂在Pd(0)的分解来解释。预催化剂CODPd(CH2TMS)(2)(PD1)中的1，5-环辛二烯(COD)配体是一种有益的添加剂。稳定的Buchwald络合物XPhosPdG2可以代替络合物Pd1与外源COD和2-dicyclohexylphosphino-2‘，4’，6‘-triisopropylbiphenyl(XPhos)一起使用。外源XPhos的加入显著增加了催化剂的周转次数，提高了重现性。
Reported herein is a mechanistic investigation into the palladium-catalyzed decarboxylative cross-coupling of sodium benzoates and chloroarenes. The reaction was found to be first-order in Pd. A minimal substituent effect was observed with respect to chloroarene, and the reaction was zero-order with respect to chloroarene. Palladium-mediated decarboxylation was assigned as the turnover-limiting step based on an Eyring plot and density functional theory computations. Catalyst performance was found to vary based on the electrophile, which is best explained by catalyst decomposition at Pd(0). The 1,5-cyclooctadiene (COD) ligand contained in the precatalyst CODPd(CH2TMS)(2) (Pd1) was shown to be a beneficial additive. The bench-stable Buchwald complex XPhosPdG2 could be used with exogenous COD and 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (XPhos) instead of complex Pd1. Adding exogenous XPhos significantly increased the catalyst turnover number and enhanced reproducibility.