Zu einem Systematischen Verständnis des Einflusses der Temperatur auf Glykosylierungsreaktionen DOI Creative Commons
Owen T. Tuck, Eric T. Sletten, José Danglad‐Flores

и другие.

Angewandte Chemie, Год журнала: 2022, Номер 134(15)

Опубликована: Янв. 15, 2022

Abstract Die Bildung von glykosidischen Bindungen ist eine ständige Herausforderung in der Praxis. Mit dem Ziel, die Reproduzierbarkeit und Effizienz Synthese Oligosacchariden zu verbessern, wird hier Beziehung zwischen Aktivierung des Glykosyl‐Donors Reaktionstemperatur untersucht. Ein neues semi‐automatisches Assay zeigt, dass Mitglieder einer Gruppe Thioglykoside unterschiedlich auf bei verschiedenen Temperaturen reagieren. Muster Schutzgruppen Thio‐Aglykons führen bemerkenswerten Unterschieden Temperaturempfindlichkeit Glykosyl‐Donors. Wir das Konzept Donor‐Aktivierungstemperatur ein, um experimentelle Erkenntnisse erfassen, folgern daraus, Glykosylierungen, unterhalb dieser Referenztemperatur durchgeführt werden, schädlichen Nebenreaktionen entgehen. Kentnisse über Aktivierungstemperaturen ermöglichen vereinfachte Temperaturbehandlung erleichtern Optimierung Verwendung Bei isothermen Glykosylierung Aktivierungstemperatur halbierten sich benötigten Bausteinäquivalente im Vergleich bisher Lösungs‐ Festphasen‐Oligosaccharidsynthese verwendeten Standard‐“Rampen”‐Verfahren.

Towards a Systematic Understanding of the Influence of Temperature on Glycosylation Reactions DOI
Owen T. Tuck, Eric T. Sletten, José Danglad‐Flores

и другие.

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(15)

Опубликована: Янв. 15, 2022

Glycosidic bond formation is a continual challenge for practitioners. Aiming to enhance the reproducibility and efficiency of oligosaccharide synthesis, we studied relationship between glycosyl donor activation reaction temperature. A novel semi-automated assay revealed diverse responses members panel thioglycosides at various temperatures. The patterns protecting groups thiol aglycon combine cause remarkable differences in temperature sensitivity among building blocks. We introduce concept capture experimental insights, reasoning that glycosylations performed below this reference evade deleterious side reactions. Activation temperatures enable simplified treatment facilitate optimization usage. Isothermal glycosylation halved equivalents block required comparison standard "ramp" regime used solution- solid-phase synthesis to-date.

Язык: Английский

Процитировано

31
More than a Leaving Group: N‐Phenyltrifluoroacetimidate as a Remote Directing Group for Highly α‐Selective 1,2‐cis Glycosylation DOI
Xianglai Liu, Yingying Song, Ao Liu

и другие.

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(21)

Опубликована: Март 10, 2022

The anomeric configuration can greatly affect the biological functions and activities of carbohydrates. Herein, we report that N-phenyltrifluoroacetimidoyl (PTFAI), a well-known leaving group for catalytic glycosylation, act as stereodirecting challenging 1,2-cis α-glycosylation. Utilizing rapidly accessible 1,6-di-OPTFAI glycosyl donors, TMSOTf-catalyzed glycosylation occurred with excellent α-selectivity broad substrate scope, remaining 6-OPTFAI be cleaved chemoselectively. remote participation is supported by first characterization crucial 1,6-bridged bicyclic oxazepinium ion intermediates low-temperature NMR spectroscopy. These cations were found to relatively stable mainly responsible present stereoselectivities. Further application highlighted in reactions toward trisaccharide heparins well convergent synthesis chacotriose derivatives using bulky 2,4-di-O-glycosylated donor.

Язык: Английский

Процитировано

22
Direct Synthesis of 2,6‐Dideoxy‐β‐glycosides and β‐Rhamnosides with a Stereodirecting 2‐(Diphenylphosphinoyl)acetyl Group DOI
Xianglai Liu, Yetong Lin,

Wenyi Peng

и другие.

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(33)

Опубликована: Июнь 13, 2022

Anomeric stereocontrol is usually one of the major issues in synthesis complex carbohydrates, particularly those involving β-configured 2,6-dideoxyglycoside and d/l-rhamnoside moieties. Herein, we report that 2-(diphenylphosphinoyl)acetyl highly effective as a remote stereodirecting group direct these challenging β-glycosides under mild conditions. A deoxy-trisaccharide mimic sugar chain landomycin E was prepared stereospecifically high yield. The synthetic potential also highlighted Citrobacter freundii O-antigens composed [→4)-α-d-Manp-(1→3)-β-d-Rhap(1→4)-β-d-Rhap-(1→] repeating unit, wherein convergent assembly up to nonasaccharide realized with strongly β-directing trisaccharide donor. Variable-temperature NMR studies indicate presence intermolecular H-bonding between donor bulky acceptor spectral evidence support concept hydrogen-bond-mediated aglycone delivery.

Язык: Английский

Процитировано

21
Direct Experimental Characterization of a Bridged Bicyclic Glycosyl Dioxacarbenium Ion by 1H and 13C NMR Spectroscopy: Importance of Conformation on Participation by Distal Esters DOI
Kapil Upadhyaya, Yagya Prasad Subedi, David Crich

и другие.

Angewandte Chemie International Edition, Год журнала: 2021, Номер 60(48), С. 25397 - 25403

Опубликована: Сен. 20, 2021

Low-temperature NMR studies with a 4-C-methyl-4-O-benzoyl galactopyranosyl donor enable the observation and characterization of bridged bicyclic dioxacarbenium ion arising from participation by distal ester. Variable-temperature reveal this to decompose at temperatures above ≈-30 °C. In absence methyl group, formation is not observed. It concluded that typical secondary esters in glycosylation reactions disfavored ground state conformation ester which it stereoelectronically impossible. Methylation converts conformationally more labile tertiary ester, removes barrier, renders favorable. Nevertheless, minor changes selectivity model on going both low room temperature argue against group being major stereodirecting factor even for system.

Язык: Английский

Процитировано

26
Direct Experimental Characterization of a Bridged Bicyclic Glycosyl Dioxacarbenium Ion by 1H and 13C NMR Spectroscopy: Importance of Conformation on Participation by Distal Esters DOI
Kapil Upadhyaya, Yagya Prasad Subedi, David Crich

и другие.

Angewandte Chemie, Год журнала: 2021, Номер 133(48), С. 25601 - 25607

Опубликована: Сен. 20, 2021

Abstract Low‐temperature NMR studies with a 4‐ C ‐methyl‐4‐ O ‐benzoyl galactopyranosyl donor enable the observation and characterization of bridged bicyclic dioxacarbenium ion arising from participation by distal ester. Variable‐temperature reveal this to decompose at temperatures above ≈−30 °C. In absence methyl group, formation is not observed. It concluded that typical secondary esters in glycosylation reactions disfavored ground state conformation ester which it stereoelectronically impossible. Methylation converts conformationally more labile tertiary ester, removes barrier, renders favorable. Nevertheless, minor changes selectivity model on going both low room temperature argue against group being major stereodirecting factor even for system.

Язык: Английский

Процитировано

5
More than a Leaving Group: N‐Phenyltrifluoroacetimidate as a Remote Directing Group for Highly α‐Selective 1,2‐cis Glycosylation DOI
Xianglai Liu, Yingying Song, Ao Liu

и другие.

Angewandte Chemie, Год журнала: 2022, Номер 134(21)

Опубликована: Март 10, 2022

Abstract The anomeric configuration can greatly affect the biological functions and activities of carbohydrates. Herein, we report that N ‐phenyltrifluoroacetimidoyl (PTFAI), a well‐known leaving group for catalytic glycosylation, act as stereodirecting challenging 1,2‐ cis α‐glycosylation. Utilizing rapidly accessible 1,6‐di‐OPTFAI glycosyl donors, TMSOTf‐catalyzed glycosylation occurred with excellent α‐selectivity broad substrate scope, remaining 6‐OPTFAI be cleaved chemoselectively. remote participation is supported by first characterization crucial 1,6‐bridged bicyclic oxazepinium ion intermediates low‐temperature NMR spectroscopy. These cations were found to relatively stable mainly responsible present stereoselectivities. Further application highlighted in reactions toward trisaccharide heparins well convergent synthesis chacotriose derivatives using bulky 2,4‐di‐ O ‐glycosylated donor.

Язык: Английский

Процитировано

2
Direct Synthesis of 2,6‐Dideoxy‐β‐glycosides and β‐Rhamnosides with a Stereodirecting 2‐(Diphenylphosphinoyl)acetyl Group DOI
Xianglai Liu, Yetong Lin,

Wenyi Peng

и другие.

Angewandte Chemie, Год журнала: 2022, Номер 134(33)

Опубликована: Июнь 13, 2022

Abstract Anomeric stereocontrol is usually one of the major issues in synthesis complex carbohydrates, particularly those involving β‐configured 2,6‐dideoxyglycoside and d / l ‐rhamnoside moieties. Herein, we report that 2‐(diphenylphosphinoyl)acetyl highly effective as a remote stereodirecting group direct these challenging β‐glycosides under mild conditions. A deoxy‐trisaccharide mimic sugar chain landomycin E was prepared stereospecifically high yield. The synthetic potential also highlighted Citrobacter freundii O‐antigens composed [→4)‐α‐ ‐Man p ‐(1→3)‐β‐ ‐Rha (1→4)‐β‐ ‐(1→] repeating unit, wherein convergent assembly up to nonasaccharide realized with strongly β‐directing trisaccharide donor. Variable‐temperature NMR studies indicate presence intermolecular H‐bonding between donor bulky acceptor spectral evidence support concept hydrogen‐bond‐mediated aglycone delivery.

Язык: Английский

Процитировано

2
Zu einem Systematischen Verständnis des Einflusses der Temperatur auf Glykosylierungsreaktionen DOI Creative Commons
Owen T. Tuck, Eric T. Sletten, José Danglad‐Flores

и другие.

Angewandte Chemie, Год журнала: 2022, Номер 134(15)

Опубликована: Янв. 15, 2022

Abstract Die Bildung von glykosidischen Bindungen ist eine ständige Herausforderung in der Praxis. Mit dem Ziel, die Reproduzierbarkeit und Effizienz Synthese Oligosacchariden zu verbessern, wird hier Beziehung zwischen Aktivierung des Glykosyl‐Donors Reaktionstemperatur untersucht. Ein neues semi‐automatisches Assay zeigt, dass Mitglieder einer Gruppe Thioglykoside unterschiedlich auf bei verschiedenen Temperaturen reagieren. Muster Schutzgruppen Thio‐Aglykons führen bemerkenswerten Unterschieden Temperaturempfindlichkeit Glykosyl‐Donors. Wir das Konzept Donor‐Aktivierungstemperatur ein, um experimentelle Erkenntnisse erfassen, folgern daraus, Glykosylierungen, unterhalb dieser Referenztemperatur durchgeführt werden, schädlichen Nebenreaktionen entgehen. Kentnisse über Aktivierungstemperaturen ermöglichen vereinfachte Temperaturbehandlung erleichtern Optimierung Verwendung Bei isothermen Glykosylierung Aktivierungstemperatur halbierten sich benötigten Bausteinäquivalente im Vergleich bisher Lösungs‐ Festphasen‐Oligosaccharidsynthese verwendeten Standard‐“Rampen”‐Verfahren.

Процитировано

0