Oxidative and reductive ring opening of endo‐3,4‐<i>O</i>‐(4‐methoxybenzylidene) acetals of 1, 6‐anhydro‐β‐D‐galactopyranoses

Abstract

Abstract Cleavage of the endo ‐3, 4‐ O ‐(4‐methoxybenzylidene) acetal rings of 1, 6‐anhydro‐β‐D‐galactopyranose derivatives with LiAlH 4 ‐AlCl 3 , NaCNBH 3 ‐HCl or NMe 3 ‐AlCl 3 gives predominantly axial 3‐ O ‐(4‐methoxybenzyl) ether derivatives. Oxidative opening of the same acetal functions with DDQ affords the corresponding 3‐ O ‐(4‐methoxybenzoyl) derivatives. The (4‐methoxybenzyl) group can be removed selectively with DDQ and survives acetolysis of the 1, 6‐anhydro bond.