Bifunctional ligands in combination with phosphines and Lewis acidic phospheniums for the carbonylative Sonogashira reaction†
Abstract
The combination of phosphine-ligated Pd catalysis and phosphenium(V) Lewis acid catalysis has been developed for the carbonylative Sonogashira reaction using phosphino-phosphenium salts (L1–L4) as bifunctional ligands, in which the Lewis acidic phosphenium(V) cations can form secondary bonds with O atoms (in CO) to cooperatively stabilize Pd–acyl intermediates.