Abstract
The rare earth metal and hafnium triflate-catalyzed cationic benzylation of various nucleophiles using benzylic alcohols is described. The reaction of benzylic alcohols with aromatic compounds in nitromethane in the presence of catalytic amount of metal triflate gave Friedel-Crafts-type benzylation products in high yield. Direct use of the alcohol as a source of an electrophile produces only water as a side product. Water-tolerant rare-earth metal triflates effectively catalyzed the alkylation under non-anhydrous conditions and the catalysts could be reused up to three times. The benzylation system also showed compatibility over a wide range of nucleophiles such as olefin, allylsilane, enol acetates, diketones, ketoesters, alcohols, and amides. The reaction conditions of various combinations of benzylic alcohols and nucleophiles were easily optimized by the two-dimensional catalysts-temperature screenings using La, Yb, Sc, and Hf triflates.
