Combined Experimental and Computational Mechanistic Investigation of the Palladium-Catalyzed Decarboxylative Cross-Coupling of Sodium Benzoates with Chloroarenes

Abstract

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 the chloroarene and the reaction was zero order with respect to chloroarene. Palladium mediated decarboxylation was assigned as the turn-over limiting step based on an Eyring plot and DFT computations. Catalyst performance was found to vary based on the electrophile, which is best explained by catalyst decomposition at Pd(0). The COD ligand contained in the precatalyst CODPd(CH2TMS)2 (Pd1) was shown to be a beneficial additive. The bench stable Buchwald complex XPhos-PdG2 could be used with exogenous COD and XPhos instead of complex Pd1. Adding exogenous XPhos significantly increased the catalyst TON and enhanced reproducibility.