An efficient synthetic route to O-(2-O-benzyl-3,4-di-O-acetyl-?/?-l-fucopyranosyl)-trichloroacetimidate

An efficient synthetic route to prepare O -(2- -benzyl-3,4-di- -acetyl-?/?- l -fucopyranosyl)-trichloroacetimidate from -fucose was developed by introducing the thiophenyl group at anomeric center and benzylidene functional protect 3 4 positions. Although three approaches were considered, best result obtained when, after 2-hydroxyl benzylation, both protective groups simultaneously removed using acetic anhydride perchloric acid supported on silica as catalyst. Selective deacetylation of tri- -acetate followed reaction resultant hemiacetal with trichloroacetonitrile DBU afforded trichloroacetimidate an overall yield 56% -fucose. • The is almost 2.5 times higher than reported. protection avoids mixed acetal formation. One less step required when anhydride-perchloric Silica used. Less chromatographic purification compared reported method.