title: Synthesis of alpha- and beta-glycosyl asparagine ethylene isosteres (C-glycosyl asparagines) via sugar acetylenes and Garner aldehyde coupling.
abstract: A convergent approach has been developed for the synthesis of C-glycosyl amino acids in which the glycinyl moiety CH(NH2)CO2H is connected to the anomeric center of the sugar residue by a three carbon atom tether. Essentially, these compounds are isosteres of N-glycosyl asparagines in which the amide group has been replaced by an ethylene bridge. Following the coupling of alpha- or beta-D-linked lithium C-glycoside acetylides with N-Boc D-serinal acetonide (Garner aldehyde), the resulting adducts were transformed into the final N-Boc-C-glycosyl-alpha-aminopentanoic acids via reduction of the triple bond, deoxygenation, and oxidative cleavage of the oxazolidine ring. By this protocol, 12 C-glycosyl asparagines, six pairs of alpha- and beta-anomers, have been prepared incorporating the gluco, galacto, manno, and the corresponding 2-acetamido-2-deoxy residues.
authors.affiliation: Dipartimento di Chimica, Laboratorio di Chimica Organica, Università di Ferrara, Via Borsari 46, 44100 Ferrara, Italy. adn@dns.unife.it
authors.forename: Alessandro
authors.initials: A
authors.lastname: Dondoni
authors.forename: Giandomenico
authors.initials: G
authors.lastname: Mariotti
authors.forename: Alberto
authors.initials: A
authors.lastname: Marra
mesh_terms: D000114:Acetylene / Q000737:chemistry*; D000447:Aldehydes / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry*; D001216:Asparagine / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D005998:Glycine / Q000737:chemistry; D006027:Glycosides / Q000737:chemistry*; D006031:Glycosylation; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010421:Pentanoic Acids / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000447:Aldehydes; D000596:Amino Acids; D006027:Glycosides; D010421:Pentanoic Acids; D001216:Asparagine; D000114:Acetylene; D005998:Glycine