In Situ NMR and Kinetics Reveal Origins of Regioselectivity Differences for Epichlorohydrin Ring-Opening in Lewis and Brønsted Acid Zeolites DOI
David W. Flaherty, David M. Potts, Huston Locht

и другие.

Research Square (Research Square), Год журнала: 2025, Номер unknown

Опубликована: Апрель 30, 2025

Abstract Altering the quantities and organization of reactive species at active sites enables control turnover rates regioselectivities (rate ratios) for ring-opening epichlorohydrin (C3H5ClO) across two orders magnitude. Kinetic analysis suggests that parallel monomolecular (SN1) bimolecular (SN2) substitution mechanisms contribute to observed C3H5ClO reactions with methanol (CH3OH) over both Lewis (Sn-BEA) Brønsted acid (Al-BEA) zeolites in liquid solvents. In situ solid-state 13C-nuclear magnetic resonance spectroscopy (SS-NMR) measurements give direct evidence proposed ring-opened carbocations activated CH3OH intermediates these catalysts. Interpretation time-resolved operando 13C-SS-NMR spectra show C3H5ClO-derived CH3OH-derived surface convert products through SN1 SN2 reaction subsequently form distinct produce regioisomers. These NMR also reveal a concomitant shift from increases coverage achieved by local concentrations CH3OH, C3H5ClO, diluting CH3CN. This knowledge provides new insight into roles confinement on regioselectivity catalytic organic solid-liquid interfaces.

Язык: Английский

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation DOI Creative Commons
Rituparna Das, Balaram Mukhopadhyay

Beilstein Journal of Organic Chemistry, Год журнала: 2025, Номер 21, С. 369 - 406

Опубликована: Фев. 17, 2025

Stereoselective glycosylations are one of the most challenging tasks synthetic glycochemists. The protecting building blocks on glycosides contribute significantly in attaining required stereochemistry resulting glycosides. Strategic installation suitable groups C-2 position, vicinal to anomeric carbon, renders neighbouring group participation, whereas distal C-3, C-4, and C-6 positions often claimed exhibit remote participation with carbon. Neighbouring being widely studied help glycochemists design protocols for multistep synthesis complex oligosaccharides turn, standardise process glycosylation towards a particular stereochemical output. While has been quite effective achieving produced glycosides, exhibits comparatively less efficacy complete stereoselectivity reactions. Remote is still highly debated topic scientific community. However, implementing participating role reactions practised achieve better stereocontrol facilitate formation synthetically glycosidic linkages.

Язык: Английский

Процитировано

0
Theoretical Study on the Key Influence of Ionic Liquid on the Synthesis Method of HMX by DPT DOI
Fangjian Shang,

Huaxin Liu,

Jianyong Liu

и другие.

Journal of Chemical Information and Modeling, Год журнала: 2025, Номер unknown

Опубликована: Фев. 24, 2025

The role of ionic liquids in the nitration synthesis HMX from DPT is explored this study by using quantum chemical calculations and AIMD-metadynamics methods. findings reveal that formation NO2+ NO+ enhanced while significantly lowering energy barriers critical reaction pathways, such as nitration, nitrosation, hydroxylation, through supramolecular structure. Moreover, research results further demonstrate catalytic environmentally friendly green characteristics influence appropriate acidity on HMX.

Язык: Английский

Процитировано

0
Amorphization evolution study of CrCoFeNiMn high entropy alloy for mechanical performance optimization by deep potential molecular dynamics DOI Creative Commons

Wentao Zhou,

Jia Song, Lve Lin

и другие.

npj Computational Materials, Год журнала: 2025, Номер 11(1)

Опубликована: Март 13, 2025

Язык: Английский

Процитировано

0
Structure-Based Mechanism and Specificity of Human Galactosyltransferase β3GalT5 DOI Creative Commons
Jennifer M. Lo, Chih‐Chuan Kung, Ting-Jen Rachel Cheng

и другие.

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Март 25, 2025

Human β1,3-galactosyltransferase 5 (β3GalT5) is a key enzyme involved in the synthesis of glycans on glycoproteins and glycolipids that are associated with various important biological functions, especially tumor malignancy cancer progression, has been considered as promising target for development anticancer agents. In this study, we determined X-ray structures β3GalT5 complex stable donor analogue UDP-2-fluorogalactose or native substrate UDP-galactose (UDP-Gal) several glycan acceptors at different reaction steps. Based obtained from our experiments, catalyzes transfer galactose UDP-Gal to broad spectrum an SN2-like mechanism; however, absence acceptor, slowly converted UDP two other products, one through mechanism water acceptor oxocarbenium-like product, presumably SN1-like mechanisms. The structure, mechanism, specificity presented study advance understanding enzymatic glycosylation provide valuable insights application drug design targeting β3GalT5-associated cancer.

Язык: Английский

Процитировано

0
In Situ NMR and Kinetics Reveal Origins of Regioselectivity Differences for Epichlorohydrin Ring-Opening in Lewis and Brønsted Acid Zeolites DOI
David W. Flaherty, David M. Potts, Huston Locht

и другие.

Research Square (Research Square), Год журнала: 2025, Номер unknown

Опубликована: Апрель 30, 2025

Abstract Altering the quantities and organization of reactive species at active sites enables control turnover rates regioselectivities (rate ratios) for ring-opening epichlorohydrin (C3H5ClO) across two orders magnitude. Kinetic analysis suggests that parallel monomolecular (SN1) bimolecular (SN2) substitution mechanisms contribute to observed C3H5ClO reactions with methanol (CH3OH) over both Lewis (Sn-BEA) Brønsted acid (Al-BEA) zeolites in liquid solvents. In situ solid-state 13C-nuclear magnetic resonance spectroscopy (SS-NMR) measurements give direct evidence proposed ring-opened carbocations activated CH3OH intermediates these catalysts. Interpretation time-resolved operando 13C-SS-NMR spectra show C3H5ClO-derived CH3OH-derived surface convert products through SN1 SN2 reaction subsequently form distinct produce regioisomers. These NMR also reveal a concomitant shift from increases coverage achieved by local concentrations CH3OH, C3H5ClO, diluting CH3CN. This knowledge provides new insight into roles confinement on regioselectivity catalytic organic solid-liquid interfaces.

Язык: Английский

Процитировано

0