title: Synthesis and intramolecular glycosylation of sialyl mono-esters of o-xylylene glycol. The importance of donor configuration and nitrogen protecting groups on cyclization yield and selectivity; isolation and characterization of a N-sialyl acetamide indicative of participation by acetonitrile.
abstract: The synthesis and cyclization reactions, leading to spirocyclic medium ring-sized diolides, of o-(hydroxymethyl)xylylene monoesters of sialyl thioglycosides is described. Cyclization yields and stereoselectivities are found to vary as a function of the anomeric stereochemistry of the thioglycoside and of the N5 protecting group, and these effects are discussed in terms of the reaction mechanism. Cyclization in the presence of acetonitrile results in the isolation and characterization of a Ritter-type N-sialyl acetamide, which affords strong evidence for the participation of acetonitrile in the form of sialyl nitrilium ions.
authors.affiliation: Department of Chemistry, Wayne State University, Detroit, MI 48202, USA.
authors.forename: Harsha
authors.initials: H
authors.lastname: Amarasekara
authors.affiliation: Department of Chemistry, Wayne State University, Detroit, MI 48202, USA. Electronic address: dcrich@chem.wayne.edu.
authors.forename: David
authors.initials: D
authors.lastname: Crich
mesh_terms: D000081:Acetamides / Q000737:chemistry; D000097:Acetonitriles / Q000737:chemistry*; D003500:Cyclization; D004952:Esters / Q000737:chemistry*; D006018:Glycols / Q000138:chemical synthesis* / Q000737:chemistry; D006031:Glycosylation; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D000081:Acetamides; D000097:Acetonitriles; D004952:Esters; D006018:Glycols
keywords: Lactonization; N-Glycosyl amide; Ritter reaction; Sialic acid; Spirodiolide; Thioglycoside