Direct, microwave-assisted substitution of anomeric nitrate-esters
作者:D. Jamin Keith、Steven D. Townsend
DOI:10.1016/j.carres.2017.02.005
日期:2017.4
1-nitrate-ester modality for alcohol, alkoxy, and azide coupling partners with minimal purification. While direct glycosylation of nitrate esters ultimately proved unsuccessful, we have demonstrated that an anomeric nitrate-ester can be converted directly to a trichloroacetimidate in a short and simple one-pot procedure, bypassing lower yielding two-step sequences.
O-[Methyl (2-O-acetyl-3-O-benzyl-4-O-levulinyl-alpha, and beta-L-idopyranosid)uronate] trichloroacetimidate and the corresponding n-pentenyl glycosides are efficient L-iduronic acid glycosyldonors. Both have been used for the high-yielding synthesis of basic disaccharide blocks which are useful for the subsequent synthesis of complex oligosaccharides related to heparin/heparan sulfate, and dermatan
Preparation of diversely protected 2-azido-2-deoxyglycopyranoses from glycals
作者:Stanislas Czernecki、Ebtissam Ayadi
DOI:10.1139/v95-046
日期:1995.3.1
6-0-tert-butyldimethylsilyl derivatives as well as with 1,s-anhydro-4,6-0-benzylidene-2-deoxy-d-lyxo- hex-1-enitol and its 3-0-acetyl and 3-0-benzyl derivatives, which were transformed into phenyl2-azido-2- deoxy-a-d-selenogalactopyranoside derivatives in good yield. In the second step, hydrolysis of these selenogly- cosi&s afforded diversely protected glycopyranoses in high yield. Peracetylated derivatives were hydrolyzed