Organocatalyzed synthesis of 2-deoxyglycosyl azides: Application in 1,2,3-triazole linked 2-deoxyglycosides

In comparison to the significant development of catalysed reactions for the formation of 2-deoxyglycoside from glycals, synthetic methods for the direct formation of 2-deoxyglycosyl azides are less explored. Consequently, the use of the 2-deoxy sugar moieties in the studies involving N-linked modified sugars for the advancements in bio-compatible materials and therapeutics are restricted despite the C2-hydroxylated glycosyl azides finding prominent application through glycodiversifications. We herein report an organocatalysed synthesis of 2-deoxyglycosyl azides from glycals using N-Fluorobezenesulfonimide (NFSI) as a catalyst and TEMPO as a co-catalyst in 1,2-DCE. The appropriate reaction conditions were determined by systematically varying reaction parameters and subsequently employed to the synthesis of glycosyl azides from differently protected glycals. The reactions did not suffer from Ferrier rearrangement by-product and was observed to be essentially α-selective in nature. Furthermore, the azides have been tested for the synthesis of 2-deoxy sugar linked 1,2,3-triazole derivatives using "click" reaction. Several alkynes with aromatic and aliphatic substitutions have been thus reacted with the azides to obtain a new class of 2-deoxyglycosides.