Solvent-free bismuth oxycarbonate-mediated mechanochemical glycosylation: A simple greener alternative to access O-/S-glycosides efficiently.

Preparation of a variety of per-O-acylated O- and S-glycosides of a set of commonly encountered mono- and disaccharides has been achieved effectively by solvent-free grinding of the corresponding acetylated/benzoylated glycosyl bromide and the desired acceptor alcohol/thiol in the presence of bismuth carbonate in a planetary ball mill. The method is simple, requires short reaction time periods and is practical allowing it to be performed at a milligram-to multi-gram scale as required. In the cases where the product is crystalline, it was often obtained in practically pure form by crystallization (and without the need for chromatographic isolation).