One-pot synthesis of 2-substituted benzo[b]furans via Pd–tetraphosphine catalyzed coupling of 2-halophenols with alkynes

A catalyst composed of [Pd(η(3)-C3H5)Cl]2 and N,N,N',N'-tetra(diphenylphosphinomethyl)pyridine-2,6-diamine (L) was found to be effective for one-pot synthesis of 2-substituted benzo[b]furans from 2-halophenols and alkynes. For 2-bromo-3-hydroxypyridine, the catalyst loading could be as low as 1 ppm and the turnover number (TON) was up to 870,000.