Facile and regioselective dealkylation of alkyl aryl ethers using niobium(V) pentachloride

A simple and facile method for the cleavage of carbon-oxygen bonds promoted by niobium pentachloride(v) is described. Excellent yields and regioselectivities were observed with various alkyl aryl ethers to give the phenols. NMR studies revealed the formation of monoaryloxy niobium salt(v), and a neighboring-group effect may play a significant role in the regioselectivity. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006).