1-O-Alkylation of D-Glucopyranose
作者:
RichardR. Schmidt,
Manfred Reichrath,
Ute Moering,
期刊:
Journal of Carbohydrate Chemistry
(Taylor Available online 1984)
卷期:
Volume 3,
issue 1
页码: 67-84
ISSN:0732-8303
年代: 1984
DOI:10.1080/07328308408057898
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Direct 1-O-methylation of 1-O-metalated 2,3,4,6-tetra-O-benzyl-d-glucose (1) with methyl trifluoromethanesulfonate (3a) as a strong alkylating agent led to the methyl gluco-pyranosides4awith the α/β anomer ratios varying from 4:1 to 1:11 depending on solvent and temperature. With the less electrophilic trifluoromethanesulfonates ofd-glucose3band3c, ofd-ribose3d, andd-glycerol (3e) as alkylating agents,1gave the β-disaccharides and β-glycosides4b-β 4e-β, exclusively. Product formation is discussed in terms of the various nucleophilicities of the starting materials and in terms of different internal complexation. Introduction of the sterically demanding (p-methoxyphenyl)diphenyl-methyl protecting group in 6-O-position of 2,3,4-tri-O-ben-zyl-D-glucose to form8and subsequent 1-O-metalation and reaction with trifluoromethanesulfonate3cgave the α-con-nected isomaltoside9C-α. However, from 1-O-metalated8and the trifluoromethanesulfonates of glycerol3eand3funder identical reaction conditions, only the β-connected glycosides9e-β and9f-β, respectively, were obtained. Structures were assigned by1H NMR and by deprotection to known compounds.
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