Pub Date : 2000-10-01DOI: 10.1002/1521-3897(200010)342:8<736::AID-PRAC736>3.0.CO;2-#
Jennifer R. Allen, S. Danishefsky
Model studies on the transformation of the olefinic unit contained in n-pentenyl glycosides (NPGs) to glycoamino acids is described. The methodology involves a Horner-Emmons olefination with a protected glycine derived phosphonate, followed by asymmetric hydrogenation using Du-PHOS catalyst system. A variety of protecting group schemes have been investigated and their stereoselectivity in the hydrogenation reaction determined. With N-Boc and C-TSE ester protection, the diastereoselectivity in the reaction was measured by 1H NMR analysis with “racemic” product as a comparison. These modified glycoamino acids are also useful for peptide synthesis. The methodology appears to be general and was extended to include the synthesis a glycoamino acid containing the complex hexasaccharide Globo-H.
{"title":"Synthesis of Non-NaturalO-Glycosylamino Acids Derived fromn-Pentenyl Glycosides; Model Studies and Proof of Principle for Glycopeptide Synthesis","authors":"Jennifer R. Allen, S. Danishefsky","doi":"10.1002/1521-3897(200010)342:8<736::AID-PRAC736>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/1521-3897(200010)342:8<736::AID-PRAC736>3.0.CO;2-#","url":null,"abstract":"Model studies on the transformation of the olefinic unit contained in n-pentenyl glycosides (NPGs) to glycoamino acids is described. The methodology involves a Horner-Emmons olefination with a protected glycine derived phosphonate, followed by asymmetric hydrogenation using Du-PHOS catalyst system. A variety of protecting group schemes have been investigated and their stereoselectivity in the hydrogenation reaction determined. With N-Boc and C-TSE ester protection, the diastereoselectivity in the reaction was measured by 1H NMR analysis with “racemic” product as a comparison. These modified glycoamino acids are also useful for peptide synthesis. The methodology appears to be general and was extended to include the synthesis a glycoamino acid containing the complex hexasaccharide Globo-H.","PeriodicalId":14712,"journal":{"name":"Journal Fur Praktische Chemie-chemiker-zeitung","volume":"42 1","pages":"736-744"},"PeriodicalIF":0.0,"publicationDate":"2000-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80692119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-10-01DOI: 10.1002/1521-3897(200010)342:8<745::AID-PRAC745>3.0.CO;2-#
G. Kuźnik, C. Unverzagt, B. Hörsch, G. Kretzschmar
{"title":"Chemical and Enzymatic Synthesis of Modified Sialyl Lewis X Tetrasaccharides with High Affinity for E and P‐Selectin","authors":"G. Kuźnik, C. Unverzagt, B. Hörsch, G. Kretzschmar","doi":"10.1002/1521-3897(200010)342:8<745::AID-PRAC745>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/1521-3897(200010)342:8<745::AID-PRAC745>3.0.CO;2-#","url":null,"abstract":"","PeriodicalId":14712,"journal":{"name":"Journal Fur Praktische Chemie-chemiker-zeitung","volume":"9 1","pages":"745-752"},"PeriodicalIF":0.0,"publicationDate":"2000-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73384413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1992-01-01DOI: 10.1002/PRAC.19923340802
L. Horner
Selectivity: OH-, NH- and SH-Groupspecific Reagents. The Application in Organic Analysis and as Protective Groups Phosphylhalides and -pseudohalides R1R2P(O)X (X = Cl, F, CN, N3, OC6H4NO2(p)) reactdepending on X- with a different selectivity with OHNH- and SH-groups. Vinylsulfones ArSO2CH = CH2 are SH-selective. Silanes R3SiH are OH-selective. By exchange of one ligand bound on P, SO2 or Si by the 5-dimethylamino resp. the 5-methoxynaphthalinogroup reagents are formed, which combine group selectivity with fluorescence. The fluorescence is quenched if a ligand or the leaving group is substituted by a NO2-group. The fluorescence appears again if after the group selective fixation the ligand with the nitrogroup is split off. In serine enzymes (α-chymotrypsine, trypsin, butyryl- and acetylcholinesterase, subtilisine) and insuline (after the reductive opening of the S-S bridges) the primary OH-groups in the active site in the enzymes resp. the SH groups in the reduced insuline were substituted with fluorescing groups using group selective fluorescing reagents.
{"title":"Selektivitätsstudien: OH-, NH- und SH-gruppenspezifische Reagentien – ihre Anwendung in der organischen Analytik und als Schutzgruppen in der Synthese†","authors":"L. Horner","doi":"10.1002/PRAC.19923340802","DOIUrl":"https://doi.org/10.1002/PRAC.19923340802","url":null,"abstract":"Selectivity: OH-, NH- and SH-Groupspecific Reagents. The Application in Organic Analysis and as Protective Groups Phosphylhalides and -pseudohalides R1R2P(O)X (X = Cl, F, CN, N3, OC6H4NO2(p)) reactdepending on X- with a different selectivity with OHNH- and SH-groups. Vinylsulfones ArSO2CH = CH2 are SH-selective. Silanes R3SiH are OH-selective. By exchange of one ligand bound on P, SO2 or Si by the 5-dimethylamino resp. the 5-methoxynaphthalinogroup reagents are formed, which combine group selectivity with fluorescence. The fluorescence is quenched if a ligand or the leaving group is substituted by a NO2-group. The fluorescence appears again if after the group selective fixation the ligand with the nitrogroup is split off. In serine enzymes (α-chymotrypsine, trypsin, butyryl- and acetylcholinesterase, subtilisine) and insuline (after the reductive opening of the S-S bridges) the primary OH-groups in the active site in the enzymes resp. the SH groups in the reduced insuline were substituted with fluorescing groups using group selective fluorescing reagents.","PeriodicalId":14712,"journal":{"name":"Journal Fur Praktische Chemie-chemiker-zeitung","volume":"113 1","pages":"645-655"},"PeriodicalIF":0.0,"publicationDate":"1992-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80468639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1897-12-31DOI: 10.1007/978-3-663-07224-9_10
J. Troeger
{"title":"Über die Einwirkung von Alkoholischem Kaliumsulfid und Alkoholischem Kaliumsulfhydrat auf Symmetrische Dibromsubstitute von Sulfonen","authors":"J. Troeger","doi":"10.1007/978-3-663-07224-9_10","DOIUrl":"https://doi.org/10.1007/978-3-663-07224-9_10","url":null,"abstract":"","PeriodicalId":14712,"journal":{"name":"Journal Fur Praktische Chemie-chemiker-zeitung","volume":"29 15","pages":"445-469"},"PeriodicalIF":0.0,"publicationDate":"1897-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91512094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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