Executive Summary : | C2-modified sugars are a core structural motif in various biologically relevant compounds isolated from natural sources. Glycochemists focus on developing synthetic C2-glycopeptides, 2-C-branched sugars, and functionalized glycosides to enhance their application as therapeutics. Glycals are the primary building blocks for derivatization at C2 of sugars and have been used for the synthesis of diverse sugars and 2-deoxy sugars. New age glycochemistry has invoked catalyzed methods for glycal functionalization and the synthesis of modified sugars. Recent advances in photo/metal catalyzed radical generation methods have seen new heights in olefin functionalizations, especially difunctionalization of styrene derivatives. This proposal aims to difunctionalize glycals using radicals formed under catalytic initiation and clean energy conditions. The overall reaction will proceed via C/N radical attack at C2 of glycals with formation of radical at C1 position. This radical can be either oxidized to the oxocarbenium ion or quenched by radical transfer reagent to afford corresponding glycosides. Radical sources that can be activated in the presence of photoredox catalyst or metal catalysts will be explored. The proposal addresses C2-modified sugars bearing 3 types of groups at C2 – amido, aryl, and trifluoromethyl. C2-amidation will use amidyl radical sources like pyridinium salts, NFSI, amido oxy acids, and aryl radicals generated from known sources. C2-aryl glycals will be directly obtained under catalytic pathways without a nucleophile. |