Generation of Glycosyl Radicals from Glycosyl Sulfoxides and Its Use in the Synthesis ofC‐linked Glycoconjugates

Abstract

We here report glycosyl sulfoxides appended with an aryl iodide moiety as readily available,air and moisture stable precursors to glycosyl radicals.These glycosyl sulfoxides could be converted to glycosyl radicals by way of arapid and efficient intramolecular radical substitution event. The use of this type of precursors enabled the synthesis of various complex Clinked glycoconjugates under mild conditions.T his reaction could be performed in aqueous media and is amenable to the synthesis of glycopeptidomimetics and carbohydrate-DNA conjugates. Scheme 1. a) Glycosyl radicals as valuable intermediates in C-glycoside synthesis. b) Our strategy to generate glycosyl radicals.

A Radical Approach to Making Unnatural Amino Acids: Conversion of C−S Bonds in Cysteine Derivatives into C−C Bonds

“…The Maruoka group [11c] applied this process in the generation alkyl radicals and glycosyl radicals. Our group [11d] recently employed this process to generate glycosyl radicals, which were further utilized in the preparation of complex glycoconjugates. In our current design depicted in Scheme 1 b, we take advantage of the high reactivity of thiol groups toward various electrophiles [12] to generate sulfide 8 , and exploit the facile radical substitution process to access radical 4 .…”

Synthesis of C-acyl furanosides via the cross-coupling of glycosyl esters with carboxylic acids

“…The dearth of furanosylation methods may be associated with the lack of furanosyl radical precursors that can be used for cross-coupling. Pyranosyl radicals have been generated from various unnatural glycosyl derivatives, including bromides, 18 xanthates, 19 glycals, 20 stannanes, 21 thiol ethers, 22 acyl tellurides, 23 and trifluoroborates. 24 Precursors to furanosyl radicals, however, are limited to unnatural tetrahydrofuran derivatives with a carboxylic acid at the C1 position, restricting the scope of carbohydrate substrates.…”

Nonenzymatic StereoselectiveS-Glycosylation of Polypeptides and Proteins

“…However, these methods need to use protected substrates and require conditions that may not be tolerated by biomolecules. In continuation of our interest in glycochemistry, we report here a strategy for S -glycopeptide synthesis shown in Scheme b. This method features the design and use of bench-stable allyl glycosyl sulfones ( 1 ) as the glycosylating agents.…”