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Stereoselective synthesis and 2D NMR study of S‐D ‐glucopyranoside
Author(s) -
Fei ChangPei,
Chan T. H.
Publication year - 1989
Publication title -
acta chimica sinica english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 0256-7660
DOI - 10.1002/cjoc.19890070311
Subject(s) - chemistry , anomer , benzoxazole , benzothiazole , bromide , trimethylsilyl , carbon 13 nmr , chemical shift , stereochemistry , medicinal chemistry , base (topology) , proton nmr , protonation , organic chemistry , ion , mathematical analysis , mathematics
2, 3, 4‐Tri‐ O ‐benzyl‐6‐ O trimethylsilyl‐α‐ D ‐glucopyranosyl bromide reacted with RSH compounds (R = Et, t ‐Bu, PhCH 2 , p ‐PhBu t , Ph, 2‐benzoxazole, 2‐benzothiazole), with diisopropylethylamine as base, to give S‐D ‐glucosides. The α‐ and β‐ anomeric ratio was dependent on the p K a. value of the thiol compound. If p K a value was less than or equal to 7, β‐anomer was obtained. If p K a value was equal to or more than 11, α anomer was obtained. If p K a value was between 9 and 10.6, a mixture of α‐ and β‐anomer was obtained. The probable mechanism was discussed. The chemical shifts of proton and carbon in these S‐D ‐glucosides were measured and verified by 2D NMR (cosy and hetcor).