title: From solution phase to "on-column" chemistry: trichloroacetimidate-based glycosylation promoted by perchloric acid-silica.
abstract: [reaction: see text] Activation of ester-protected glycosyl trichloroacetimidate donors by perchloric acid immobilized on silica afforded 1,2-trans disaccharides in 60-90% yields. Applying this approach to one-pot sequential glycosylation resulted in efficient syntheses of the N-linked glycan trimannoside and Le(X) and Le(A) trisaccharides in very good yield (76%, 62%, and 59% yields, respectively). Solution phase reactions were also translated to a solid phase format; priming the top of a standard silica chromatography column with perchloric acid immobilized on silica facilitated "on-column" glycosylation with subsequent "in situ" purification of products. Coupling yields from this approach were comparable to those obtained from the corresponding solution-phase disaccharide couplings. A series of glycosylated amino acids were also synthesized in high yield with use of the on-column approach.
authors.affiliation: Centre for Carbohydrate Chemistry, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich, UK.
authors.forename: Balaram
authors.initials: B
authors.lastname: Mukhopadhyay
authors.forename: Sarah V
authors.initials: SV
authors.lastname: Maurer
authors.forename: Nadine
authors.initials: N
authors.lastname: Rudolph
authors.forename: Renate M
authors.initials: RM
authors.lastname: van Well
authors.forename: David A
authors.initials: DA
authors.lastname: Russell
authors.forename: Robert A
authors.initials: RA
authors.lastname: Field
mesh_terms: D000081:Acetamides; D000596:Amino Acids / Q000737:chemistry; D062845:Chloroacetates; D006031:Glycosylation; D015394:Molecular Structure; D010472:Perchlorates / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013402:Sugar Alcohols / Q000737:chemistry; D014238:Trichloroacetic Acid / Q000737:chemistry
chemical_list: D000081:Acetamides; D000596:Amino Acids; D062845:Chloroacetates; D010472:Perchlorates; D013402:Sugar Alcohols; D014238:Trichloroacetic Acid; D012822:Silicon Dioxide; C009528:trichloroacetamide