title: Synthesis of O-glycopyranosyl heterocyclic ketene aminals and their use as glycosyl donors.
abstract: The synthesis and reactions of glycopyranosyl heterocyclic ketene aminals were investigated. Under mild conditions, the benzoyl-substituted heterocyclic ketene aminals 3 or 4 underwent O-glycosylation with tetra-O-acetyl-alpha-D-glucopyranosyl bromide (1) using mercuric cyanide or silver trifluoromethanesulfonate as catalyst in acetonitrile to give O-glycopyranosyl heterocyclic ketene aminals 5-7 and 8-11, respectively. The beta-anomers were the sole products. By the O-glycosylation of heterocyclic ketene aminals with 1, the O-attack of heterocyclic ketene aminals was carried out for the first time. Some of 5-11 in the synthesis of oligosaccharides 14 and 15 can provide a valuable leaving group at the anomeric position of the glycopyranosyl ring. Compounds 6c or 10c may be potentially useful as glycosyl donors in the synthesis of oligosaccharides.
authors.affiliation: Institute of Chemistry, Academia Sinica, Beijing, People's Republic of China.
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Li
authors.forename: L B
authors.initials: LB
authors.lastname: Wang
authors.forename: Z T
authors.initials: ZT
authors.lastname: Huang
mesh_terms: D004187:Disaccharides / Q000138:chemical synthesis; D005030:Ethylenes / Q000378:metabolism*; D006027:Glycosides / Q000138:chemical synthesis*; D006031:Glycosylation; D006571:Heterocyclic Compounds / Q000737:chemistry*; D007659:Ketones / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D009844:Oligosaccharides / Q000138:chemical synthesis
chemical_list: D004187:Disaccharides; D005030:Ethylenes; D006027:Glycosides; D006571:Heterocyclic Compounds; D007659:Ketones; D009844:Oligosaccharides; C008223:ketene