Inhibition of reductive elimination of diorganopalladium species by formation of tetraorganopalladates

Abstract

Reductive elimination of (^tBuCC)₂Pd(PPh₃)₂ to give ^tBuCCCCBu^t(4) is strongly inhibited by an excess of LiCCBu^t through the formation of Li₂Pd(CCBu^t)₄, which does not readily decompose to produce (4); these results provide, for the first time, a mechanistic interpretation of the hitherto puzzling inhibitory action of highly electropositive metals, such as Li, in Pd-promoted coupling reactions.