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We report a glycosyl radical-based, 1,2-trans-selective synthesis of C-aryl glycosides of 2-deoxy-2-amino-sugars from glycals via photoredox PCET/Ni dual catalysis. Mechanistic studies indicate that glycosyl radical formation involves the generation of an N-radical through a proton-coupled electron transfer (PCET) process, followed by its addition to the glycal. This protocol features: a) the use of an inexpensive organic photosensitizer and readily available glycals and aryl bromides; b) good functional group tolerance for both aryl bromides and glycal substrates; c) excellent diastereoselectivity, with exclusive formation of the 1,2-trans C-glycosides in all cases. Furthermore, the reaction could be conducted on gram-scale and is suitable for the late-stage modification of complex molecule. Deprotection experiments demonstrated complementary stability profiles between the oxazolidinone protecting group employed here and the dihydrooxazole group in our previous work.
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http://dx.doi.org/10.1002/chem.202502233 | DOI Listing |
Chemistry
September 2025
National Engineering Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang, 330022, China.
We report a glycosyl radical-based, 1,2-trans-selective synthesis of C-aryl glycosides of 2-deoxy-2-amino-sugars from glycals via photoredox PCET/Ni dual catalysis. Mechanistic studies indicate that glycosyl radical formation involves the generation of an N-radical through a proton-coupled electron transfer (PCET) process, followed by its addition to the glycal. This protocol features: a) the use of an inexpensive organic photosensitizer and readily available glycals and aryl bromides; b) good functional group tolerance for both aryl bromides and glycal substrates; c) excellent diastereoselectivity, with exclusive formation of the 1,2-trans C-glycosides in all cases.
View Article and Find Full Text PDFCarbohydr Res
August 2025
Bose Institute, Bidhan Nagar, Kolkata, 700091, India. Electronic address:
Glycosylation is potentially one of the most important reactions in glycochemistry, where precise control over the anomeric selectivity is crucial for synthesizing biologically relevant glycoconjugates. Over the last two decades, the advent of visible light chemistry for the generation of glycosyl radicals and its application in the synthesis of glycosides has revolutionized the impact on the stereoselectivity of glycosylation. The visible light-driven radical-based reactions offer exceptional functional group tolerance, operate under mild reaction conditions, and have emerged as a powerful tool for synthesizing potent glycosyl compounds, which include aryl/alkyl glycosides, 2-deoxy sugar, glycosylamino acid, glycosylpeptides, and other glyco-conjugates.
View Article and Find Full Text PDFChembiochem
February 2025
Key Laboratory of Molecule Synthesis and Function Discovery, College of Chemistry, Fuzhou, University, Fuzhou, 350108, China.
N-glycosides exhibit diverse biological and pharmacological activities, making their efficient synthesis crucial for both biological research and drug development. Traditional acid-promoted N-glycosylation methods, which rely on the formation of oxocarbenium intermediates, often face significant challenges. These methods are water-sensitive and typically require neighboring group participation to achieve high selectivity.
View Article and Find Full Text PDFOrg Lett
January 2025
National Engineering Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang 330022, China.
We have developed a glycosyl radical-based synthesis of -alkyl glycosides through a deoxygenative Giese addition-reduction-cyclization cascade, in which readily available 1-hydroxy carbohydrates serve as precursors for glycosyl radicals and aryl alkenes function as radical acceptors. This reaction not only provides an effective method for accessing a previously underexplored class of functionalized cyclopropanes but also enhances the application of Giese addition in the synthesis of -alkyl glycosides by derivatizing the radical intermediate generated through polar cyclization to yield a cyclopropane.
View Article and Find Full Text PDFOrg Lett
September 2024
Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, School of Pharmaceutical Sciences Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
The synthesis of C1-ketonyl glycosyl compounds featuring α-selectivity has seldom been reported. We herein devise a glycosyl radical-based approach to facilely access stereoenriched ketonyl glycosyl compounds via an Ir photoredox-catalyzed desulfurative addition to silyl enol ethers, using in situ-generated tetrafluoropyridinyl thioglycosides from glycosyl 1-thiols as radical precursors. This protocol features readily prepared starting materials, mild conditions, excellent functional group tolerance, satisfactory scale-up, and notable amenability to late-stage modification of pharmaceutically relevant complex molecules.
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