The chemistry of cellobiose and lactose. Part 7. Selective benzoylation of methyl β-lactoside

Abstract

The selective benzoylation of methyl β-lactoside with various proportions of benzoyl chloride in pyridine has been studied. The 3′,6′-dibenzoate, the 3′,6,6′-tribenzoate, the 2,3′,6,6′-tetrabenzoate, and the 2,2′,3′,4′,6,6′-hexabenzoate have each been isolated, in yields of between 21 and 31%. The 2,3′,4′,6,6′- and 2,2′,3′,6,6′-pentabenzoates were also encountered, but in much lower yields. From these results it was deduced that the order of reactions of the seven hydroxy-groups in methyl β-lactoside is 6′ > 3′ > 6 > 2 > 2′,4′ > 3.