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Merging Reagent Modulation and Remote Anchimeric Assistance for Glycosylation: Highly Stereoselective Synthesis of α‐Glycans up to a 30‐mer
Author(s) -
Zhang Yunqin,
He Haiqing,
Chen Zixi,
Huang Yingying,
Xiang Guisheng,
Li Penghua,
Yang Xingkuan,
Lu Gang,
Xiao Guozhi
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202103826
Subject(s) - stereoselectivity , glycosylation , glycosidic bond , reagent , chemistry , glycan , glycosyl , combinatorial chemistry , stereochemistry , organic chemistry , glycoprotein , catalysis , biochemistry , enzyme
Abstract The efficient synthesis of long, branched, and complex carbohydrates containing multiple 1,2‐cis glycosidic linkages is a long‐standing challenge. Here, we report a merging reagent modulation and 6‐O‐levulinoyl remote anchimeric assistance glycosylation strategy, which is successfully applied to the first highly stereoselective synthesis of the branched Dendrobium Huoshanense glycans and the linear Longan glycans containing up to 30 contiguous 1,2‐cis glucosidic bonds. DFT calculations shed light on the origin of the much higher stereoselectivities of 1,2‐cis glucosylation with 6‐O‐levulinoyl group than 6‐O‐acetyl or 6‐O‐benzoyl groups. Orthogonal one‐pot glycosylation strategy based on glycosyl ortho‐alkynylbenzoates and ortho‐(1‐phenylvinyl)benzoates has been demonstrated in the efficient synthesis of complex glycans, precluding such issues as aglycon transfer inherent to orthogonal one‐pot synthesis based on thioglycosides.