Multigram scale preparation of a semi-synthetic N-trifluoroacetyl protected chondroitin disaccharide building block: Towards the stereoselective synthesis of chondroitin sulfates disaccharides.

The chemoselective N-trifluoroacetylation of a chondroitin disaccharide obtained from controlled acid hydrolysis of a commercially available polymeric chondroitin sulfate is reported for the first time. We also described the multi-gram scale synthesis of a donor block having a benzylidene moiety further used for the expeditious and stereocontrolled synthesis of glycosides fitted with various aglycons. Stereocontrolled β-glycosylation, sulfation and efficient N-TFA deprotection steps afforded the desired disaccharides in good yields.