Palladium-catalyzed coupling of tetraorganotin compounds with aryl and benzyl halides. Synthetic utility and mechanism

TLDR: In this article, the reaction of substituted bromobenzenes with tetramethyltin catalyzed by 1 is accelerated by electron-withdrawing groups; however, a simple Hammett correlation is not observed.

Abstract: Palladium complexes catalyze the coupling of tetraorganotin compounds with benzyl and aryl halides, benzylchlorobis(triphenylphosphine)palladium(II) (1) being the catalyst of choice. Various functional groups are tolerated by this reaction and generally high yields of the cross-coupled products are obtained. Oxygen has a considerable accelerating effect on the reaction, whereas triphenylphosphine has little effect. The reaction of substituted bromobenzenes with tetramethyltin catalyzed by 1 is accelerated by electron-withdrawing groups; however, a simple Hammett correlation is not observed. Optically active ..cap alpha..-deuteriobenzyl bromide reacts with tetramethyltin to afford optically active ..cap alpha..-deuterioethylbenzene with inversion of configuration. Homocoupling is the main reaction observed when lithium or Grignard reagents react with benzyl chloride under the influence of various palladium catalysts.