Microwave-Assisted Hirao Reaction of Heteroaryl Bromides and >P(O)H Reagents Using Pd(OAc)2 as the Catalyst Precursor in the Absence of Added P-Ligands

Abstract

Bromopyridines, bromotiophenes and 3-bromofuran were reacted with diphenylphosphine oxide or diethyl phosphite under microwave irradiation using Pd(OAc)2 as the catalyst precursor together with some excess of the >P(O)H reagent. Hence, there was no need for the usual mono- and bidentate P-ligands. The >P(O)-functionalized heterocycles were obtained in variable (55-95%) yields. The results of our “green” protocol were in most cases better than those of the literature methods.