Efficient route to orthogonally protected precursors of 2-acylamino-2-deoxy-3-O-substituted-β-d-glucopyranose derivatives and use thereof

An efficient route to two 3-O-acyl-2-deoxy-4,6-O-isopropylidene-2-trichloroacetamido-d-glucopyranosyl trichloroacetimidate donors is reported. As demonstrated for the 3-O-acetyl derivative, these building blocks are exquisite β-d-glucosamine donors when reacted either with simple alcohols or with complex oligosaccharides. Besides, their protection pattern is compatible with selective deprotection and subsequent chain elongation at O-3 of the newly incorporated glucosamine residue.

The trichloroacetimidate donor (R = Ac) was used successfully in the synthesis of S. flexneri branched tri- and pentasaccharides.