Chemistry of 4,6-O-benzylidene-D-glycopyranosyl triflates:: Contrasting behavior between the gluco and manno series

被引:150
作者
Crich, D [1 ]
Cai, WL [1 ]
机构
[1] Univ Illinois, Dept Chem, Chicago, IL 60607 USA
关键词
D O I
10.1021/jo990243d
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
Activation of either anomer of S-phenyl 2,3-di-O-benzyl-4,6-O-benzylidene-1-deoxy-1-thia-D-glucopyranoside with triflic anhydride in dichloromethane at -78 degrees C in the presence of 2,6-di-tert-butyl-4-methylpyridine affords a highly active glycosylating species which, on addition of alcohols, provides cl-glucosides with high selectivity. This selectivity stands in stark contrast to the analogous mannopyranoside series, which affords the beta-mannosides with excellent selectivity under the same conditions. Low-temperature NMR experiments support the notion that a glucosyl triflate is formed in the initial activation step. Possible reasons for the diverging stereoselectivity in the gluco and manno series are discussed.
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页码:4926 / 4930
页数:5
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