Electron-deficient pyridinium salts/thiourea cooperative catalyzed <i>O</i>-glycosylation via activation of <i>O</i>-glycosyl trichloroacetimidate donors
作者:Mukta Shaw、Yogesh Kumar、Rima Thakur、Amit Kumar
DOI:10.3762/bjoc.13.236
日期:——
The glycosylation of O-glycosyl trichloroacetimidate donorsusing a synergistic catalytic system of electron-deficient pyridinium salts/aryl thiourea derivatives at room temperature is demonstrated. The acidity of the adduct formed by the 1,2-addition of alcohol to the electron-deficient pyridinium salt is increased in the presence of an aryl thiourea derivative as an hydrogen-bonding cocatalyst. This
Iron(<scp>iii</scp>) chloride modulated selective 1,2-trans glycosylation based on glycosyl trichloroacetimidate donors and its application in orthogonal glycosylation
作者:Mana Mohan Mukherjee、Nabamita Basu、Rina Ghosh
DOI:10.1039/c6ra21859h
日期:——
FeCl3 can also modulate the 1,2-trans selectivity of the reaction of 2-O-alkylated gluco- and galacto-pyranosyl trichloroacetimidates with phenolic compounds leading to the generation of the corresponding β-O-aryl glycosides in excellent yield and selectivity. Apart from these the present methodology has been successfully utilized for double glycosylation and orthogonal glycosylation reactions along
Here we report a glucosylation strategy mediated by ZnI2, a cheap and mild Lewis acid, for the highly stereoselective construction of 1,2-cis-O-glycosidic linkages using easily accessible and common 4,6-O-tethered glucosyl donors. The versatility and effectiveness of the α-glucosylation strategy were demonstrated successfully with various acceptors, including complex alcohols. This approach demonstrates
The practical formalsynthesis of the anticoagulant drug fondaparinux sodium 1 was accomplished using an optimized modular synthetic strategy. The important pentasaccharide 2, a precursor for the synthesis of fondaparinux sodium, was synthesized on a 10 g scale in 14 collective steps with 3.5% overall yield from well-functionalized monosaccharide building blocks. The strategy involved a convergent
Expedient synthesis of a pentasaccharide related to the O-specific polysaccharide of Escherichia coli O117:K98:H4 strain
作者:Ishani Bhaumik、Anup Kumar Misra
DOI:10.1039/c4ra10538a
日期:——
A convenient synthetic strategy has been developed for the synthesis of a pentasaccharide, related to the O-specific polysaccharide ofEscherichia coliO117:K98:H4 strain, using sequential glycosylations of functionalized monosaccharide moieties.