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

Characterization of Elusive Reaction Intermediates Using Infrared Ion Spectroscopy: Application to the Experimental Characterization of Glycosyl Cations DOI Creative Commons

Floor ter Braak,

Hidde Elferink, Kas J. Houthuijs

и другие.

Accounts of Chemical Research, Год журнала: 2022, Номер 55(12), С. 1669 - 1679

Опубликована: Май 26, 2022

ConspectusA detailed understanding of the reaction mechanism(s) leading to stereoselective product formation is crucial and predicting driving development new synthetic methodology. One way improve our mechanisms characterize intermediates involved in formation. Because these are reactive, they often unstable therefore difficult using experimental techniques. For example, glycosylation reactions critical steps chemical synthesis oligosaccharides need be provide desired α- or β-diastereomer. It remains challenging predict control stereochemical outcome reactions, their remain a hotly debated topic. In most cases, take place via continuum between SN1- SN2-like pathways. pathways proceeding displacement contact ion pair relatively well understood because can characterized by low-temperature NMR spectroscopy. contrast, SN1-like solvent-separated pair, also known as glycosyl cation, poorly understood. more investigate cation highly reactive. The reactive nature cations complicates characterization have short lifetime rapidly equilibrate with corresponding pair. To overcome this hurdle enable study stability structure, generated mass spectrometer absence solvent counterion gas phase. ease formation, stability, fragmentation been studied spectrometry (MS). However, MS alone provides little information about structure cations. By combining (MS) infrared spectroscopy (IRIS), determination gas-phase structures has achieved. IRIS enables recording spectra cations, which assigned matching reference predicted from quantum chemically calculated vibrational spectra. Here, we review setups that discuss various date. depends on relative configuration monosaccharide substituents, influence through both steric electronic effects. scope relevance relation condensed-phase discussed. We expect workflow reviewed here reactivity extended many other types involving difficult-to-characterize ionic intermediates.

Язык: Английский

Процитировано

23
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
Chemical Synthesis of Complex Carbohydrates DOI
Paul Kosma

Handbook of experimental pharmacology, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

Язык: Английский

Процитировано

0
A Bioactive Synthetic Outer‐Core Oligosaccharide Derived from a Klebsiella pneumonia Lipopolysaccharide for Bacteria Recognition DOI Creative Commons

Dushen Chen,

Akhilesh Kumar Srivastava,

Justyna Dubrochowska

и другие.

Chemistry - A European Journal, Год журнала: 2023, Номер 29(25)

Опубликована: Янв. 20, 2023

There is an urgent need for new treatment options carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae), which a common cause of life-threatening hospital- and community-acquired infections. Prophylactic or therapeutic vaccination may offer approach to control these infections, however, none has yet been approved human use. Here, we report the chemical synthesis outer core tetra- pentasaccharide derived from lipopolysaccharide K. pneumoniae. The oligosaccharides were equipped with aminopentyl linker, facilitated conjugation carrier proteins CRM

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