Recent Advances in the Regioselective Functionalization of Carbohydrates Using Non-Enzymatic Catalysts

Protection-deprotection strategies are one of the most essential techniques in the synthesis of complex compounds. However, if a functional group can be freely introduced onto a particular position of a compound without interference from other functionalities, some protection-deprotection steps in the synthesis can be eliminated. Though some advances have been recently reported for the removal of these steps in natural product synthesis by groups such as Baran et al. (1), the use of protecting groups is still necessary in the synthesis of polyols such as glycosides and polysaccharides. Additionally, no non-enzymatic methods are available to directly functionalize these polyols because methods to selectively recognize a particular OH group in polyols or monosaccharides, which is a unit of polyols, have not been sufficiently developed. In this review, we report recent advances in this field from the literature and our own approaches for the regioselective functionalization of carbohydrates employing non-enzymatic catalysts.