title: Concise synthesis of a pentasaccharide related to the anti-leishmanial triterpenoid saponin isolated from Maesa balansae.
abstract: Concise synthesis of the glycone part (a pentasaccharide) of the anti-leishmanial triterpenoid saponin isolated from Maesa balansae is reported. A late-stage TEMPO-mediated oxidation of a primary hydroxyl group to carboxylic acid has been achieved under phase-transfer conditions. Glycosylations were performed either by thioglycoside or glycosyl trichloroacetimidate activation using sulfuric acid immobilized on silica (H2SO4-silica) in conjunction with N-iodosuccinimide and alone, respectively. H2SO4-silica was proved to be a better choice as promoter than conventional Lewis acid promoters such as TfOH or TMSOTf.
authors.affiliation: Indian Institute of Science Education and Research-Kolkata, HC-7, Sector-III, Kolkata 700 106, India.
authors.forename: Vishal Kumar
authors.initials: VK
authors.lastname: Rajput
authors.forename: Balaram
authors.initials: B
authors.lastname: Mukhopadhyay
mesh_terms: D000081:Acetamides; D000818:Animals; D000981:Antiprotozoal Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D062845:Chloroacetates; D006031:Glycosylation; D007891:Leishmania / Q000187:drug effects; D008698:Mesylates / Q000737:chemistry; D008956:Models, Chemical; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000494:pharmacology; D029623:Primulaceae / Q000737:chemistry*; D012503:Saponins / Q000138:chemical synthesis* / Q000494:pharmacology; D012822:Silicon Dioxide / Q000737:chemistry; D013388:Succinimides / Q000737:chemistry; D013464:Sulfuric Acids / Q000737:chemistry; D013865:Thioglycosides / Q000737:chemistry; D014238:Trichloroacetic Acid / Q000737:chemistry; D014297:Trimethylsilyl Compounds / Q000737:chemistry; D014315:Triterpenes / Q000737:chemistry*
chemical_list: D000081:Acetamides; D000981:Antiprotozoal Agents; D062845:Chloroacetates; D008698:Mesylates; D009844:Oligosaccharides; D012503:Saponins; D013388:Succinimides; D013464:Sulfuric Acids; D013865:Thioglycosides; D014297:Trimethylsilyl Compounds; D014315:Triterpenes; C053353:trimethylsilyl trifluoromethanesulfonate; C008155:N-iodosuccinimide; D014238:Trichloroacetic Acid; D012822:Silicon Dioxide; C009528:trichloroacetamide; C033158:sulfuric acid