title: Synthesis of some monodeoxyfluorinated methyl and 4-nitrophenyl alpha-D-mannobiosides and a related 4-nitrophenyl alpha-D-mannotrioside.
abstract: Treatment of methyl 3,4,6-tri-O-benzyl-2-O-(2,3,4-tri-O-acetyl-alpha-D-mannopyranosyl)-alpha -D- mannopyranoside with N,N-diethylaminosulfur trifluoride (Et2NSF3), followed by O-deacetylation and catalytic hydrogenolysis, afforded methyl 2-O-(6-deoxy-6-fluoro-alpha-D-mannopyranosyl)-alpha-D-mannopyranoside (8). Methyl 6-deoxy-6-fluoro-2-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside (11) was similarly obtained from methyl 3-O-benzyl-2-O-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl-alpha-D- mannopyranoside. 1,2,3,4-Tetra-O-acetyl-6-deoxy-6-fluoro-beta-D-mannopyranose (13), used for the synthesis of the 4-nitrophenyl analogs of 8 and 11, as well as their 3-O-linked isomers, was obtained by treatment of 1,2,3,4-tetra-O-acetyl-beta-D-mannopyranose with Et2NSF3. Treatment of 13 with 4-nitrophenol in the presence of tin(IV) chloride, followed by sequential O-deacetylation, isopropylidenation, acetylation, and cleavage of the acetal group, afforded 4-nitrophenyl 4-O-acetyl-6-deoxy-6-fluoro-alpha-D-mannopyranoside (18). Treatment of 13 with HBr in glacial acetic acid furnished the 6-deoxy-6-fluoro bromide 19. Glycosylation of diol 18 with 20 gave 4-nitrophenyl 4-O-acetyl-6-deoxy-6-fluoro-3-O- (21) and -2-O-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl)-alpha-D- mannopyranoside (23) in the ratio of approximately 2:1, together with a small proportion of a branched trisaccharide. 4-Nitrophenyl 4,6-di-O-acetyl-alpha-D-mannopyranoside was similarly glycosylated with bromide 19 to give 4-nitrophenyl 4,6-di-O-acetyl-3-O- and -2-O-(2,3,4-tri- O-acetyl-6-deoxy-6-fluoro-alpha-D-mannopyranosyl)-alpha-D-mannopyranosid e. The various di- and tri-saccharides were O-deacetylated by Zemplén transesterification.
authors.affiliation: Department of Gynecologic Oncology, Roswell Park Memorial Institute, Buffalo, New York 14263.
authors.forename: S H
authors.initials: SH
authors.lastname: Khan
authors.forename: R K
authors.initials: RK
authors.lastname: Jain
authors.forename: S A
authors.initials: SA
authors.lastname: Abbas
authors.forename: K L
authors.initials: KL
authors.lastname: Matta
mesh_terms: D002240:Carbohydrate Sequence; D004187:Disaccharides / Q000138:chemical synthesis*; D005461:Fluorine; D006027:Glycosides / Q000138:chemical synthesis*; D008362:Mannosides / Q000138:chemical synthesis*; D008969:Molecular Sequence Data; D014312:Trisaccharides / Q000138:chemical synthesis
chemical_list: D004187:Disaccharides; D006027:Glycosides; D008362:Mannosides; D014312:Trisaccharides; D005461:Fluorine