Convergent Synthesis of Digalactosyl Diacylglycerols

Efficient convergent chemical syntheses of digalactosyl diacylglycerols (DGDGs), which have both a galactose galactose alpha(1 -> 6)-linkage and a galactose-glycerol beta-linkage along with a diacylglycerol containing various kinds of fatty acids, have been accomplished. In order to achieve a concise synthesis, we chose to use allylic protective groups as permanent protective groups. We have also achieved alpha- and beta-selective glycosylations for the respective linkages with high yields as the key steps.