Transglucosidation of methyl and ethyl d-glucopyranosides by alcoholysis

The transglucosidations of methyl 4- O-methyl-α- and -β- d-glucopyranoside in ethanolic camphor-10-sulfonic acid, and of ethyl 4- O-methyl-α- and -β- d-glucopyranoside in methanolic camphor-10-sulfonic acid, have been studied. Samples were removed at intervals and the proportions of the glucosides d...

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Bibliographic Details
Published in:Carbohydrate research 2002-03, Vol.337 (6), p.517-521
Main Authors: Garegg, Per J, Johansson, Karl-Jonas, Konradsson, Peter, Lindberg, Bengt, Trumpakaj, Zygmunt
Format: Article
Language:English
Subjects:
Camphor - analogs & derivatives
Camphor - chemistry
Carbohydrate Sequence
Ethanol - chemistry
Glucosides - chemistry
Glycosylation
Kinetics
Mechanistic studies
Methanol - chemistry
Methylation
Methylglucosides - chemistry
Molecular Sequence Data
TECHNOLOGY
TEKNIKVETENSKAP
Transglucosylation
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Summary:The transglucosidations of methyl 4- O-methyl-α- and -β- d-glucopyranoside in ethanolic camphor-10-sulfonic acid, and of ethyl 4- O-methyl-α- and -β- d-glucopyranoside in methanolic camphor-10-sulfonic acid, have been studied. Samples were removed at intervals and the proportions of the glucosides determined by GC of their acetates. The results show that the anomer with the inverted configuration predominates in the initially formed product (≈59–70%). This indicates that all the studied reactions proceed via the same mechanism, involving exocyclic CO cleavage and formation of a glucopyranosylium ion, but that the eliminated alcohol exerts some steric hindrance, which favors the approach of the other alcohol from the opposite side. The initial rate constants for the formation of the two products, during the transglucosidation, have been determined.
ISSN:0008-6215
1873-426X
1873-426X
DOI:10.1016/S0008-6215(02)00005-8