Qiu X, Garden AL, Fairbanks AJ. Protecting group free glycosylation: one-pot stereocontrolled access to 1,2-
trans glycosides and (1→6)-linked disaccharides of 2-acetamido sugars.
Chem Sci 2022;
13:4122-4130. [PMID:
35440979 PMCID:
PMC8985506 DOI:
10.1039/d2sc00222a]
[Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 03/12/2022] [Indexed: 11/21/2022] Open
Abstract
Unprotected 2-acetamido sugars may be directly converted into their oxazolines using 2-chloro-1,3-dimethylimidazolinium chloride (DMC), and a suitable base, in aqueous solution. Freeze drying and acid catalysed reaction with an alcohol as solvent produces the corresponding 1,2-trans-glycosides in good yield. Alternatively, dissolution in an aprotic solvent system and acidic activation in the presence of an excess of an unprotected glycoside as a glycosyl acceptor, results in the stereoselective formation of the corresponding 1,2-trans linked disaccharides without any protecting group manipulations. Reactions using aryl glycosides as acceptors are completely regioselective, producing only the (1→6)-linked disaccharides.
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