Highly regioselective homoallyl alcohol protection through ring opening of p-methoxybenzylidene acetal

摘要

A highly regioselective homoallylic alcohol protection was achieved in the reductive cleavage of anisylidene acetal with DIBAL-H during the selective protection of hydroxyl group in terminal unsaturated diols which was unlikely compare to the diols present adjacent to internal and cyclic double bond. Reductive cleavage of terminal olefenic diols protected as its acetals gave exclusively ally! alcohol product in good to excellent yield. Though the actual reason of such observation is not quite clear, the current reductive protocol can be applied as an efficient solution for indirect protection of less reactive hydroxy group in preference to that of more reactive allylic one as PMB-mono ether. (C) 2016 Elsevier Ltd. All rights reserved.