PubMed:2379188 JSONTXT

{"project":"sentences","denotations":[{"id":"TextSentencer_T1","span":{"begin":0,"end":136},"obj":"Sentence"},{"id":"TextSentencer_T2","span":{"begin":137,"end":449},"obj":"Sentence"},{"id":"TextSentencer_T3","span":{"begin":450,"end":652},"obj":"Sentence"},{"id":"TextSentencer_T4","span":{"begin":653,"end":908},"obj":"Sentence"},{"id":"TextSentencer_T5","span":{"begin":909,"end":1168},"obj":"Sentence"},{"id":"TextSentencer_T6","span":{"begin":1169,"end":1259},"obj":"Sentence"},{"id":"TextSentencer_T7","span":{"begin":1260,"end":1533},"obj":"Sentence"},{"id":"TextSentencer_T8","span":{"begin":1534,"end":1770},"obj":"Sentence"},{"id":"TextSentencer_T9","span":{"begin":1771,"end":1858},"obj":"Sentence"},{"id":"T1","span":{"begin":0,"end":136},"obj":"Sentence"},{"id":"T2","span":{"begin":137,"end":449},"obj":"Sentence"},{"id":"T3","span":{"begin":450,"end":652},"obj":"Sentence"},{"id":"T4","span":{"begin":653,"end":908},"obj":"Sentence"},{"id":"T5","span":{"begin":909,"end":1168},"obj":"Sentence"},{"id":"T6","span":{"begin":1169,"end":1259},"obj":"Sentence"},{"id":"T7","span":{"begin":1260,"end":1533},"obj":"Sentence"},{"id":"T8","span":{"begin":1534,"end":1770},"obj":"Sentence"},{"id":"T9","span":{"begin":1771,"end":1858},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"Synthesis of some monodeoxyfluorinated methyl and 4-nitrophenyl alpha-D-mannobiosides and a related 4-nitrophenyl alpha-D-mannotrioside.\nTreatment 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."}

{"project":"NCBITAXON","denotations":[{"id":"T1","span":{"begin":589,"end":596},"obj":"OrganismTaxon"},{"id":"T2","span":{"begin":661,"end":668},"obj":"OrganismTaxon"},{"id":"T3","span":{"begin":859,"end":866},"obj":"OrganismTaxon"},{"id":"T4","span":{"begin":1368,"end":1375},"obj":"OrganismTaxon"}],"attributes":[{"id":"A1","pred":"db_id","subj":"T1","obj":"100829"},{"id":"A2","pred":"db_id","subj":"T2","obj":"100829"},{"id":"A3","pred":"db_id","subj":"T3","obj":"100829"},{"id":"A4","pred":"db_id","subj":"T4","obj":"100829"}],"text":"Synthesis of some monodeoxyfluorinated methyl and 4-nitrophenyl alpha-D-mannobiosides and a related 4-nitrophenyl alpha-D-mannotrioside.\nTreatment 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."}