DDQ-Mediated Oxidation of 4,6-O-Methoxybenzylidene-Protected Saccharides in the Presence of Various Nucleophiles: Formation of 4-OH, 6-Cl, and 6-Br Derivatives
摘要:
Treatment of 4,6-O-p-methoxybenzylidene-protected pyranosidic mono- and disaccharides with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), in the presence of a few equivalents of water, gave the corresponding 6- and 4-O-p-methoxybenzoates with unprotected hydroxyl groups in the 4- and 6-position in the ratio similar to 4:1 and in 85-98% yield. Dry conditions in the presence of halide salts gave the 6-deoxychloro and -bromo 4-O-p-methoxybenzoates exclusively, in >90% yield.
Synthesis of Double-Chain Bis-Sulfone Neoglycolipids of the 2-, 3-, and 6-Deoxyglobotrioses
摘要:
Partially protected 2-(trimethylsilyl)ethyl 2- and 3-deoxyglucosides and 6-deoxylactoside were synthesised via various routes and glycosylated with galabiosyl and galactosyl donors to give the corresponding deoxytrisaccharides. Removal of the protecting groups gave the 2-(trimethylsilyl)ethyl 2-, 3-, and 6-deoxyglobotriosides. Transformation of the protected trisaccharides into trichloroacetimidates, via the corresponding hemiacetals, proceeded in similar to 80% overall yield. Glycosylation of 3-(hexadecylsulfonyl)-2-[(hexadecylsulfonyl)methyl]propanol with the trisaccharidic trichloroacetimidates, in 72-79% yield, followed by removal of protecting groups, gave the title neoglycolipids.
Synthesis of Double-Chain Bis-Sulfone Neoglycolipids of the 2-, 3-, and 6-Deoxyglobotrioses
作者:Zhiyuan Zhang、Göran Magnusson
DOI:10.1021/jo951914k
日期:1996.1.1
Partially protected 2-(trimethylsilyl)ethyl 2- and 3-deoxyglucosides and 6-deoxylactoside were synthesised via various routes and glycosylated with galabiosyl and galactosyl donors to give the corresponding deoxytrisaccharides. Removal of the protecting groups gave the 2-(trimethylsilyl)ethyl 2-, 3-, and 6-deoxyglobotriosides. Transformation of the protected trisaccharides into trichloroacetimidates, via the corresponding hemiacetals, proceeded in similar to 80% overall yield. Glycosylation of 3-(hexadecylsulfonyl)-2-[(hexadecylsulfonyl)methyl]propanol with the trisaccharidic trichloroacetimidates, in 72-79% yield, followed by removal of protecting groups, gave the title neoglycolipids.
DDQ-Mediated Oxidation of 4,6-<i>O</i>-Methoxybenzylidene-Protected Saccharides in the Presence of Various Nucleophiles: Formation of 4-OH, 6-Cl, and 6-Br Derivatives
作者:Zhiyuan Zhang、Göran Magnusson
DOI:10.1021/jo952177v
日期:1996.1.1
Treatment of 4,6-O-p-methoxybenzylidene-protected pyranosidic mono- and disaccharides with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), in the presence of a few equivalents of water, gave the corresponding 6- and 4-O-p-methoxybenzoates with unprotected hydroxyl groups in the 4- and 6-position in the ratio similar to 4:1 and in 85-98% yield. Dry conditions in the presence of halide salts gave the 6-deoxychloro and -bromo 4-O-p-methoxybenzoates exclusively, in >90% yield.