Controlled dealkylation by BBr3: efficient synthesis of para-alkoxy-phenols

Controlled dealkylation of dialkyl-aryl-ethers by substoichiometric BBr3 has been developed as a general tool for the differentiation of the oxygen functions in hydroquinone derivatives. The reaction proceeds smoothly at rt either on linear or branched alkyl-ethers and provides the corresponding p-alkoxy-phenols RO-Ar-OH in high yields. With respect to the conventional alkylation path of Ar(OH)2, this process represents a tunable and convenient route to key intermediates for conjugated materials with differentiated side chains.