Cross-metathesis of C-allyl iminosugars with alkenyl oxazolidines as a key step in the synthesis of C-iminoglycosyl alpha-amino acids. A route to iminosugar containing C-glycopeptides.
[structures: see text] A general access to a novel class of sugar alpha-amino acids composed of iminofuranose and iminopyranose residues anomerically linked to the glycinyl group through an alkyl chain is described. A set of eight compounds was prepared by the same reaction sequence involving as an initial step the Grubbs Ru-carbene-catalyzed cross-metathesis (CM) of various N-Cbz-protected allyl C-iminoglycosides with N-Boc-vinyl- and N-Boc-allyloxazolidine. The isolated yields of the CM products (mixtures of E- and Z-alkenes) varied in the range 40-70%. Each mixture was elaborated by first reducing the carbon-carbon double bond using in situ generated diimide and then unveiling the N-Boc glycinyl group [CH(BocNH)CO2H] by oxidative cleavage of the oxazolidine ring by the Jones reagent. All amino acids were characterized as their methyl esters. The insertion of a model C-iminoglycosyl-2-aminopentanoic acid into a tripeptide via sequential carboxylic and amino group coupling with L-phenylalanine derivatives was carried out as a demonstration of the potential of these sugar amino acids in designed glycopeptide synthesis.
Dipartimento di Chimica, Laboratorio di Chimica Organica, Università di Ferrara, Via L. Borsari 46, 44100-Ferrara, Italy. adn@dns.unife.it
Alessandro
A
Dondoni
Pier Paolo
PP
Giovannini
Daniela
D
Perrone
D000475:Alkenes / Q000737:chemistry; D000498:Allyl Compounds / Q000737:chemistry*; D000596:Amino Acids / Q000138:chemical synthesis*; D002384:Catalysis; D003500:Cyclization; D006020:Glycopeptides / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry*; D006031:Glycosylation; D007097:Imines / Q000737:chemistry*; D015394:Molecular Structure; D010080:Oxazoles / Q000737:chemistry*; D010084:Oxidation-Reduction; D013237:Stereoisomerism
D000475:Alkenes; D000498:Allyl Compounds; D000596:Amino Acids; D006020:Glycopeptides; D006027:Glycosides; D007097:Imines; D010080:Oxazoles; C064210:oxazolidine