Ligand-controlled, transition-metal catalyzed site-selective modification of glycosides

Carbohydrates play important roles in many physiological and pathological events. The preparation of the derivatives and conjugates of carbohydrates is often needed to help interrogate and exploit their biological properties. Owning to their structural complexity, one major challenge in the derivatization of carbohydrates is to control site-selectivity, that is, to selectively modify one hydroxyl group in the presence of many others. In recent years, ligand controlled transition-metal catalysis has been employed in the site-selective modification of glycosides, resulting in methodologies that enable efficient and direct syntheses of carbohydrates derivatives. In this minireview, we will focus on reactions in which the site-selectivity is controlled by the properties of the ancillary ligands of transition-metals.