Formation of ß-Configured Thioglycosides of d-Glucosamine and d-Galactosamine and Synthesis of Protected Human Milk Oligosaccharides.

We report on the stereoselective multigram scale preparation of cyclohexyl- and phenyl thioglycosides of 2-azido-2-deoxy-ß-d-gluco- and galactopyranosides from d-N-acetylglucosamine using a catalytic and solvent-free method. Two of the prepared building blocks were used as key intermediates for the synthesis of human milk oligosaccharides LNT and LNnT in their protected form.