Design and synthesis of exocyclic cyclitol aziridines as potential mechanism-based glycosidase inactivators

Abstract

Cyclophellitol aziridines have found wide application as mechanism-based, covalent, and irreversible inhibitors of retaining glycosidases. These compounds, like their parent compound, cyclophellitol (a natural product retaining beta-glucosidase inactivator), make use of the mechanism of action of retaining glycosidases, which process their substrate through the formation of a transient covalent intermediate. In contrast, inverting glycosidases, the other main family of glycosyl hydrolases, do not employ such a covalent intermediate, and, as a consequence, useful scaffolds for mechanism-based inhibitor design have yet to be discovered. In this work, we explore chemistries that allow for the construction of cyclitol aziridines with the aziridine electrophile attached in an exocyclic fashion, more distal from the anomeric carbon - thus putatively closer to an inverting glycosidase active site nucleophile. The developed chemistries have allowed for the synthesis of a focused library of differently N-substituted, alpha-and beta-glucopyranose configured cyclitol aziridines for future evaluation as inhibitors or inactivators of alpha-and beta-glucosidases alike.