
Research Square (Research Square), Год журнала: 2023, Номер unknown
Опубликована: Ноя. 2, 2023
Язык: Английский
Research Square (Research Square), Год журнала: 2023, Номер unknown
Опубликована: Ноя. 2, 2023
Язык: Английский
Chemical Society Reviews, Год журнала: 2023, Номер 52(22), С. 7773 - 7801
Опубликована: Янв. 1, 2023
The structural complexity of glycans poses a serious challenge in the chemical synthesis glycosides, oligosaccharides and glycoconjugates. Glycan complexity, determined by composition, connectivity, configuration far exceeds what nature achieves with nucleic acids proteins. Consequently, glycoside ranks among most complex tasks organic synthesis, despite involving only simple type bond-forming reaction. Here, we introduce fundamental principles bond formation summarize recent advances oligosaccharide synthesis.
Язык: Английский
Процитировано
46Nature Communications, Год журнала: 2024, Номер 15(1)
Опубликована: Март 13, 2024
Abstract Attaining complete anomeric control is still one of the biggest challenges in carbohydrate chemistry. Glycosyl cations such as oxocarbenium and dioxanium ions are key intermediates glycosylation reactions. Characterizing these highly-reactive understanding their mechanisms essential to stereoselective synthesis complex carbohydrates. Although C-2 acyl neighbouring-group participation has been well-studied, reactive more remote remain elusive challenging study. Herein, we report a workflow that utilized characterize rhamnosyl 1,3-bridged derived from C-3 p -anisoyl esterified donors. First, use combination quantum-chemical calculations infrared ion spectroscopy determine structure cationic intermediate gas-phase. In addition, establish exchange kinetics highly-reactive, low-abundance species solution-phase using chemical saturation transfer, spectroscopy, correlation heteronuclear single-quantum correlation, multiple-bond nuclear magnetic resonance spectroscopy. Finally, apply bacterial oligosaccharides. This combined approach finding answers fundamental physical-chemical questions application organic provides robust basis for elucidating
Язык: Английский
Процитировано
7Science Advances, Год журнала: 2023, Номер 9(42)
Опубликована: Окт. 18, 2023
The stereoselectivity of glycosidic bond formation continues to pose a noteworthy hurdle in synthesizing carbohydrates, primarily due the simultaneous occurrence S
Язык: Английский
Процитировано
14Chemistry - A European Journal, Год журнала: 2024, Номер 30(30)
Опубликована: Март 28, 2024
Abstract The chemical synthesis of complex oligosaccharides relies on efficient and highly reproducible glycosylation reactions. outcome a is contingent upon several environmental factors, such as temperature, acidity, the presence residual moisture, well steric, electronic, conformational aspects reactants. Each proceeds rapidly with high yield within rather narrow temperature range. For better control over glycosylations to ensure fast reliable reactions, systematic analysis 18 glycosyl donors revealed effect reagent concentration, water content, protecting groups, structure activation temperature. With these insights, we parametrize first step reaction be executed reliably efficiently.
Язык: Английский
Процитировано
5Chemistry - A European Journal, Год журнала: 2023, Номер 29(57)
Опубликована: Июль 6, 2023
A single acyloxy group at C-2 can control the outcome of nucleophilic substitution reactions pyran-derived acetals, but extent neighboring-group participation depends on a number factors. We show here that does not necessarily stereochemical acetal with weak nucleophiles. The 1,2-trans selectivity increased increasing reactivity incoming nucleophile. This trend suggests intermediacy both cis-fused dioxolenium ions and oxocarbenium in stereochemistry-determining step. In addition, as electron-donating ability neighboring decreased, preference for products increased. Computational studies how barriers ring-opening reaction transition states to provide change capacity C-2-acyloxy
Язык: Английский
Процитировано
10Nature Synthesis, Год журнала: 2024, Номер 3(11), С. 1377 - 1384
Опубликована: Июль 26, 2024
The stereoselective formation of 1,2-
Язык: Английский
Процитировано
4Molecules, Год журнала: 2025, Номер 30(2), С. 218 - 218
Опубликована: Янв. 7, 2025
Using methods of DFT, we investigated the effect electron withdrawing and donating groups on relative stability tentative glycosyl donor reaction intermediates. The calculation shows that by changing stereoelectronic properties protecting group, can influence dioxolenium type intermediates up to 10 kcal mol−1, increasing nucleophillicity 4-O-Bz intermediate becomes more stable than a triflate–donor pair. We exploited this mechanism design galactosyl donors with custom O2 O4, outcome cyclohexanol. showed no change in product distribution, which suggests neighboring group participation takes precedence over remote due kinetic barriers.
Язык: Английский
Процитировано
0The Journal of Organic Chemistry, Год журнала: 2025, Номер 90(4), С. 1585 - 1596
Опубликована: Янв. 15, 2025
Nucleophilic substitution reactions of C-2-acyloxy furanosyl acetals can be highly diastereoselective. We here show that the presence a less electron-donating p-nitrobenzoyloxy group at C-2 acetal use to control 1,2-trans stereoselectivity with higher than analogue more benzoyloxy group, just as what was observed in pyranosyl system. Computational results support reaction manifold involving both open oxocarbenium ions and cis-dioxolenium provide 1,2-cis products. Participation by C-2-(p-nitrobenzoyloxy) forms stabilized ion reacts incoming nucleophile readily The relative stability versus is much system result lower energy penalty for forming cis-fused [5,5]-bicyclic dioxolenium ion.
Язык: Английский
Процитировано
0Beilstein 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
0Communications Chemistry, Год журнала: 2025, Номер 8(1)
Опубликована: Март 7, 2025
The stereoselective introduction of glycosidic bonds is one the greatest challenges in carbohydrate chemistry. A key aspect controlling glycan synthesis glycosylation reaction which linkages are formed. outcome governed by a reactive sugar intermediate - glycosyl cation. Glycosyl cations highly unstable and short-lived, making them difficult to study using established analytical tools. However, mass-spectrometry-based techniques perfectly suited unravel structure gas phase. main approach involves isolating intermediate, free from external influences such as solvents promoters. Isolation allows examining their integrating orthogonal spectrometric spectroscopic technologies. In this perspective, recent achievements gas-phase research on highlighted. It provides an overview used probe methods for interpreting spectra. connections between data mechanisms solution explored, given that reactions typically performed solution.
Язык: Английский
Процитировано
0