0000000000046719
AUTHOR
Holger Herzner
ChemInform Abstract: Synthesis of Glycopeptides Containing Carbohydrate and Peptide Recognition Motifs
ChemInform Abstract: Oligosaccharide Synthesis via Electrophile-Induced Activation of Glycosyl-N-allylcarbamates.
Abstract Glycosyl-N-allyl carbamates, obtained by reaction of anomerically unprotected saccharides with allyl isocyanate, can be activated by an electrophile-induced cyclisation and reacted with glycosyl acceptors to form the corresponding oligosaccharides By this method the mucin core 2 trisaccharide2 has successfully been synthesized. Due to the mild glycosylation conditions even 1-O-acetyl protected glycosyl acceptors can be used. This was demonstrated in the synthesis of a 1,6-linked glucosyl trisaccharide whereby a reptitious glycosylation strategy could be applied. 1. Dedicated to the memory of Professor Akira Hasegawa.
Synthetic Inhibitors of Cell Adhesion: A Glycopeptide from E-Selectin Ligand 1 (ESL-1) with the Arabino Sialyl Lewisx Structure
Particularly selective methods are required for the synthesis of arabino sialyl Lewisx glycopeptides owing to the acid-labile β-arabinopyranoside bond. It is important for the inhibition of cell adhesion that the arabino sialyl Lewisx glycopeptide 1, which contains the Gly 672 -Asp 681 sequence of the E-selectin Ligand 1 (ESL-1), binds ten times more strongly than sialyl Lewisx to E-selectin, although it is monovalent and does not contain L-fucose, which is considered essential.
Synthesis of Glycopeptides Containing Carbohydrate and Peptide Recognition Motifs
ChemInform Abstract: Crossing the Finishing Line: Total Syntheses of the Vancomycin Aglycon.
(p-Sulfomethyl)phenylalanine as a mimic of O-sulfatyl-tyrosine in synthetic partial sequences of P-Selectin glycoprotein ligand 1 (PSGL-1)
Abstract Fmoc- l -( p -sulfomethyl)phenylalanine, a bioisosteric mimic of acid-sensitive O -sulfatyl tyrosine, was synthesized from l -tyrosine according to a novel route. Partial sequences of the recognition site of P-Selectin glycoprotein ligand 1 (PSGL-1), which contain (sulfomethyl)phenylalanine were synthesized on solid-phase. By fragment condensation, a sialyl Lewis x peptide conjugate containing a (sulfomethyl)phenylalanine mimic of O -sulfatyl tyrosine was prepared without destruction of the acid-sensitive fucoside bond within the saccharide side chain. Compounds of this type are of interest as sufficiently acid-stable potential inhibitors of P-Selectin in inflammatory processes.
Spacer-separated sialyl LewisX cyclopeptide conjugates as potential E-selectin ligands.
Completely protected sialyl LewisX azide was synthesized from a neolactosamine azide precursor carrying a 3-O-allyloxycarbonyl group as the temporary protecting group. After its Pd(0)-catalyzed deprotection and stereoselective alpha-fucosylation, the obtained LewisX azide was subjected to O-deacetylation in the galactose unit and subsequent regio- and stereoselective sialylation. Reduction of the anomeric azido group afforded the sialyl LewisX amine building block. Two molecules of this tetrasaccharide ligand were conjugated to a preformed cyclooctapeptide containing two equidistant l-asparagine units equipped with carboxy-terminated tetraethyleneglycol side chains to give, after deprotecti…