Search results for "Koenigs–Knorr reaction"

showing 3 items of 3 documents

A new method of anomeric protection and activation based on the conversion of glycosyl azides into glycosyl fluorides

1993

Glycosyl azides provide reliable anomeric protection stable to conditions for hydrolytic removal of ester groups, for reductive opening or release of acetalic diol protection, for the introduction of ether-type protection, and for glycosylation processes. The utility of this anomeric protection is further enhanced as glycosyl azides may be converted into glycosyl fluorides, which can be activated for glycosylation reactions. To this end, glycosyl azides have been subjected to 1,3-dipolar cycloaddition with di-tert-butyl acetylenedicarboxylate. On treatment with hydrogen fluoride-pyridine complex the N-glycosyl triazole derivatives directly give glycosyl fluorides.

AzidesMagnetic Resonance Spectroscopyanimal structuresAnomerGlycosylationOptical RotationMolecular Sequence DataCarbohydrate synthesismacromolecular substancesBiochemistryKoenigs–Knorr reactionAnalytical ChemistryFluoridesStructure-Activity Relationshipchemistry.chemical_compoundCarbohydrate ConformationOrganic chemistryGlycosylGlycosidesGlycosyl donorMolecular StructureOrganic ChemistryChemical glycosylationGlycosyl acceptorGeneral Medicinecarbohydrates (lipids)Carbohydrate Sequencechemistrylipids (amino acids peptides and proteins)Carbohydrate Research
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N-Glycosyl Amides as Glycosyl Donors in Stereoselective Glycosylation Reactions

2004

Due to their high stability, N-glycosyl amides have so far not been considered as glycosyl donors for glycosylation reactions. Two new procedures for the cleavage of the anomeric amide functionality under mild reaction conditions and further stereoselective in situ conversions of the activated glycosyl donors with alcohols and amines to give β-configured O- and N-glycosides are described in this article.

Reaction conditionsanimal structuresAnomerGlycosylationStereochemistryChemical glycosylationOrganic ChemistryGeneral Medicinemacromolecular substancesCleavage (embryo)Koenigs–Knorr reactionCatalysiscarbohydrates (lipids)chemistry.chemical_compoundchemistryAmidelipids (amino acids peptides and proteins)GlycosylStereoselectivityGlycosyl donorSynthesis
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Convenient Synthesis of Biologically Important Retinoids

1995

The toxic and teratogenic effects caused by the highly biologically active (all-E)-retinoic acid and its derivatives prompted us to synthesize a number of retinoids. We developed synthetic approaches to (all-E)-retinyl β-D-glucuronide 3, methyl (retinoyl β-D-glucopyranoside)uronate 5, (all-E)-retinoic acid β-D-glucopyranosyl ester 8 and (all-E)-retinoyl β-D-glucuronide 6 in high purity and yield. Compound 3 was synthesized under Koenigs-Knorr conditions from (all-E)-retinol and an α-halogenose. Compounds 5 and 8 were prepared by esterification of a silver salt of (all-E)-retinoic acid with an α-glycosyl halide in pyridine. (all-E)-Retinoyl β-D-glucuronide 6 was prepared by reaction of (all-…

chemistry.chemical_classificationChemistryOrganic ChemistryRetinoic acidHalideSalt (chemistry)Biological activityGeneral ChemistryKoenigs–Knorr reactionchemistry.chemical_compoundYield (chemistry)PyridineOrganic chemistryPhysical and Theoretical ChemistryFluorideLiebigs Annalen
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