This paper reports SVR (Support Vector Regression) and GTM (Generative Topographic Mapping) modeling of three kinetic properties of cycloaddition reactions: rate constant (logk), activation energy (Ea) and pre-exponential factor (logA). A data set of 1849 reactions, comprising (4+2), (3+2) and (2+2) cycloadditions (CA) were studied in different solvents and at different temperatures. The reactions were encoded by the ISIDA fragment descriptors generated for Condensed Graph of Reaction (CGR). For a given reaction, a CGR condenses structures of all the reactants and products into one single molecular graph, described both by conventional chemical bonds and "dynamical" bonds characterizing chemical transformations. Different scenarios of logk assessment were exploited: direct modeling, application of the Arrhenius equation and temperature-scaled GTM landscapes. The logk models with optimal cross-validated statistics (Q =0.78-0.94 RMSE=0.45-0.86) have been challenged to predict rates for the external test set of 200 reactions, comprising both reactions that were not present in the training set, and training set transformations performed under different reaction conditions. The models are freely available on our web-server: http://cimm.kpfu.ru/models.
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http://dx.doi.org/10.1002/minf.201800077 | DOI Listing |
J Org Chem
January 2025
Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstrasse 11, 48149 Münster, Germany.
Xanthine nucleosides play a significant role in the expansion of the four-letter genetic code. Herein, 7-functionalized 8-aza-7-deazaxanthine ribo- and 2'-deoxyribonucleosides are described. 2-Amino-6-alkoxy nucleosides were converted to halogenated 8-aza-7-deazaxanthine nucleosides by deamination followed by hydroxy/alkoxy substitution.
View Article and Find Full Text PDFAnal Chem
January 2025
The Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China.
The position and configuration of the C═C bond have a significant impact on the spatial conformation of unsaturated lipids, which subsequently affects their biological functions. Double bond isomerization of lipids is an important mechanism of bacterial stress response, but its in-depth mechanistic study still lacks effective analytical tools. Here, we developed a visible-light-activated dual-pathway reaction system that enables simultaneous [2 + 2] cycloaddition and catalytic - isomerization of the C═C bond of unsaturated lipids via directly excited anthraquinone radicals.
View Article and Find Full Text PDFJ Colloid Interface Sci
December 2024
Laboratory of Alternative Energy Conversion Systems, Department of Mechanical Engineering, School of Engineering, University of Thessaly, Pedion Areos 38834, Greece. Electronic address:
The coupling of carbon dioxide (CO) with epoxides to produce cyclic carbonates is a desirable decarbonization approach, but its commercial applicability is still restricted by the costly catalysts required, as well as the need for high temperature and high pressure. Herein, oxygen vacancy-rich defective tungsten oxide (WO) rich in Lewis acid sites was modified by Prussian blue (PB), and the obtained composite reaches up to 94 % styrene carbonate yield (171 mmol gh) at ambient temperature and pressure, exhibiting outstanding advantages in the photocatalytic CO cycloaddition reaction compared with currently reported photocatalysts. It is found that the introduction of PB with photothermal properties significantly enhances the capability of WO to absorb and activate CO and epoxide, along with its light utilization ability.
View Article and Find Full Text PDFEur J Med Chem
December 2024
Department of Natural Products and Medicinal Chemistry, CSIR-IICT Hyderabad, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India. Electronic address:
Investigations into fruit and vegetable processing residues (FVPRs) offer huge opportunities to discover novel therapeutics against many diseases. In this study, detailed investigation of Garcinia mangostana fruit peel extract led to the isolation and identification of ten known compounds (1-10). Further, a new series of α-mangostin derived sulphonyl piperzines, aryl alkynes and 1,2,3-triazole derivatives were synthesized using Huisgen 1,3-dipolar cyclo-addition reaction ("click" chemistry).
View Article and Find Full Text PDFJ Mol Model
January 2025
Department of Theoretical Chemistry, Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387, Krakow, Poland.
Context: The analysis of the changes in the electronic structure along intrinsic reaction coordinate (IRC) paths for model reactions: (i) ethylene + butadiene cycloaddition, (ii) prototype SN2 reaction Cl + CH3Cl, (iii) HCN/CNH isomerization assisted by water, (iv) CO + HF → C(O)HF was performed, in terms of changes in the deformation density (Δr) and the deformation of MEP (ΔMEP). The main goal was to further examine the utility of the ΔMEP as a descriptor of chemical bonding, and to compare the pictures resulting from Δr and ΔMEP. Both approaches clearly show that the main changes in the electronic structure occur in the TS region.
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