Month: November 2022

Sturala, Jiri published the artcileElectron-Deficient Heteroarenium Salts: An Organocatalytic Tool for Activation of Hydrogen Peroxide in Oxidations, SDS of cas: 42839-08-7, the main research area is heteroarenium salt organocatalytic activation hydrogen peroxide oxidations.

A series of monosubstituted pyrimidinium and pyrazinium triflates and 3,5-disubstituted pyridinium triflates were prepared and tested as simple catalysts of oxidations with hydrogen peroxide, using sulfoxidation as a model reaction. Their catalytic efficiency strongly depends on the type of substituent and is remarkable for derivatives with an electron-withdrawing group, showing reactivity comparable to that of flavinium salts which are the prominent organocatalysts for oxygenations. Because of their high stability and good accessibility, 4-(trifluoromethyl)pyrimidinium and 3,5-dinitropyridinium triflates are the catalysts of choice and were shown to catalyze oxidation of aliphatic and aromatic sulfides to sulfoxides, giving quant. conversions, high preparative yields and excellent chemoselectivity. The high efficiency of electron-poor heteroarenium salts is rationalized by their ability to readily form adducts with nucleophiles, as documented by low pKR+ values (pKR+ < 5) and less neg. reduction potentials (Ered > -0.5 V). Hydrogen peroxide adducts formed in situ during catalytic oxidation act as substrate oxidizing agents. The Gibbs free energies of oxygen transfer from these heterocyclic hydroperoxides to thioanisole, obtained by calculations at the B3LYP/6-311++g(d,p) level, showed that they are much stronger oxidizing agents than alkyl hydroperoxides and in some cases are almost comparable to derivatives of flavin hydroperoxide acting as oxidizing agents in monooxygenases.

Journal of Organic Chemistry published new progress about Activation energy. 42839-08-7 belongs to class pyrimidines, name is Ethyl pyrimidine-2-carboxylate, and the molecular formula is C7H8N2O2, SDS of cas: 42839-08-7.

Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia

Uddin, Kabir M. published the artcileNew insight into the substituent effects on the hydrolytic deamination of saturated and unsaturated cytosine, Related Products of pyrimidines, the main research area is cytosine hydrolytic deamination substituent effect thermodn property.

Ab initio calculations were carried out to understand the effect of electron donating groups (EDG) and electron withdrawing groups (EWG) at the C5 position of cytosine (Cyt) and saturated cytosine (H2Cyt) of the deamination reaction. Geometries of the reactants, transition states, intermediates, and products were fully optimized at the B3LYP/6-31G(d,p) level in the gas phase as this level of theory has been found to agree very well with G3 theories. Activation energies, enthalpies, and Gibbs energies of activation along with the thermodn. properties (ΔE, ΔH, and ΔG) of each reaction were calculated A plot of the Gibbs energies of activation (ΔG ) for C5 substituted Cyt and H2Cyt against the Hammett σ-constants reveal a good linear relationship. In general, both EDG and EWG substituents at the C5 position in Cyt results in higher ΔG and lower σ values compared to those of H2Cyt deamination reactions. C5 alkyl substituents (H, CH3, CH2CH3, CH2CH2CH3) increase ΔG values for Cyt, while the same substituents decrease ΔG values for H2Cyt which is likely due to steric effects. However, the Hammett σ-constants were found to decrease at the C5 position of cytosine (Cyt) and saturated cytosine (H2Cyt) on the deamination reaction. Both ΔG and σ values decrease for the substituents Cl and Br in the Cyt reaction, while ΔG values increase and σ decrease in the H2Cyt reaction. This may be due to high polarizability of bromine which results in a greater stabilization of the transition state in the case of bromine compared to chlorine. Regardless of the substituent at C5, the pos. charge on C4 is greater in the TS compared to the reactant complex for both the Cyt and H2Cyt. Moreover, as the charges on C4 in the TS increase compared to reactant, ΔG also increase for the C5 alkyl substituents (H, CH3, CH2CH3, CH2CH2CH3) in Cyt, while ΔG decrease in H2Cyt. In addition, anal. of the frontier MO energies for the transition state structures shows that there is a correlation between the energy of the HOMO-LUMO gap and activation energies.

International Journal of Quantum Chemistry published new progress about Activation energy. 19030-75-2 belongs to class pyrimidines, name is 5-N-Propyluracil, and the molecular formula is C7H10N2O2, Related Products of pyrimidines.

Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia

Krivokapic, Andre published the artcileRadicals in 5-methylcytosine induced by ionizing radiation. Electron magnetic resonance for structural and mechanistic analyses, Synthetic Route of 58366-64-6, the main research area is ionizing radiation X ray 5 methylcytosine radical.

Single crystals of 5-methylcytosine hemihydrate and 5-methylcytosine hydrochloride were X-irradiated and studied at 10 K and at higher temperatures using X- and K-band EPR, ENDOR and EIE spectroscopy. In the hemihydrate crystals, four radicals were identified at 10 K, one of them being the recently reported N1-deprotonated one-electron oxidation product. The other radicals were the 3αH radical and the C6 and C5 H-addition radicals (the 5-yl and 6-yl radicals, resp.). After irradiation at 295 K, only the 3αH and the 5-yl radicals were observed In the hydrochloride crystals, at least seven different radicals were present after irradiation at 10 K. These were the N1-deprotonated one-electron oxidation product, the 3αH radical, three different one-electron reduction products, and the 5- and 6-yl radicals. DFT calculations were used to assist in assigning the observed couplings. The 3αH and 5-yl radicals were dominant after thermal annealing to room temperature In neither crystal system did the N1-deprotonated oxidation product transform into the 3αH radical upon warming. The radical yield was significantly greater after irradiation at 300 K compared to that after irradiation at 10 K followed by warming to 300 K and was also considerably greater in the hydrochloride crystals than in the hemihydrate crystals.

Radiation Research published new progress about Ionizing radiation. 58366-64-6 belongs to class pyrimidines, name is 5-Methylcytosinehydrochloride, and the molecular formula is C5H8ClN3O, Synthetic Route of 58366-64-6.

Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia

Golmohammadi, Hassan published the artcileQuantitative structure-property relationship prediction of gas-to-chloroform partition coefficient using artificial neural network, Safety of Ethyl pyrimidine-2-carboxylate, the main research area is gas chloroform QSPR partition coefficient artificial neural network.

A quant. structure-property relationship (QSPR) study based on an artificial neural network (ANN) was carried out for the prediction of the gas-to-chloroform partition coefficients of a set of 338 compounds of a very different chem. nature. The genetic algorithm-partial least squares (GA-PLS) method was used as a variable selection tool. A PLS method was used to select the best descriptors and the selected descriptors were used as input neurons in neural network model. These descriptors are Gravitation index for all bonded pairs of atoms (G 2), Final heat of formation (ΔH f), Total hybridization components of the mol. dipole (μ h), DPSA-3 Difference in CPSAs (DPSA-3) and Structural Information content (order 1) (1SIC). The results obtained showed the ability of developed artificial neural networks to predict of gas-to-chloroform partition coefficients of various compounds Also this demonstrates the advantages of ANN.

Microchemical Journal published new progress about Formation enthalpy. 42839-08-7 belongs to class pyrimidines, name is Ethyl pyrimidine-2-carboxylate, and the molecular formula is C7H8N2O2, Safety of Ethyl pyrimidine-2-carboxylate.

Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia

Karthikeyan, Iyyanar published the artcileAn efficient synthesis of pyrido[1,2-a]indoles through aza-Nazarov type cyclization, Recommanded Product: Ethyl pyrimidine-2-carboxylate, the main research area is pyridoindole preparation aza Nazarov cyclization.

Transition metal free Bronsted acid mediated synthesis of biol. important pyrido[1,2-a]indole scaffolds through aza-Nazarov type cyclization of readily available diaryl(2-pyridyl)methanol using formic acid was developed. This methodol. was successfully extended to synthesize atropisomers.

Chemical Communications (Cambridge, United Kingdom) published new progress about Nazarov cyclization. 42839-08-7 belongs to class pyrimidines, name is Ethyl pyrimidine-2-carboxylate, and the molecular formula is C7H8N2O2, Recommanded Product: Ethyl pyrimidine-2-carboxylate.

Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia

Rodriguez-Jimenez, Santiago published the artcileSolvent Polarity Predictably Tunes Spin Crossover T1/2 in Isomeric Iron(II) Pyrimidine Triazoles, COA of Formula: C7H8N2O2, the main research area is solvent polarity tuning spin transition isomeric iron pyrimidyltriazole cyanato; iron pyrimidyltriazole cyanato complex solvatomorph preparation crystal structure.

Two isomeric pyrimidine-based Rdpt-type triazole ligands were made: 4-(4-methylphenyl)-3-(2-pyrimidyl)-5-phenyl-4H-1,2,4-triazole (L2pyrimidine) and 4-(4-methylphenyl)-3-(4-pyrimidyl)-5-phenyl-4H-1,2,4-triazole (L4pyrimidine). When reacted with [FeII(pyridine)4(NCE)2], where E = S, Se, or BH3, two families of mononuclear Fe(II) complexes were obtained, including six solvatomorphs, giving a total of 12 compounds: [FeII(L2pyrimidine)2(NCS)2] (1), [FeII(L2pyrimidine)2(NCSe)2] (2), 2·1.5H2O, [FeII(L2pyrimidine)2(NCBH3)2]·2CHCl3 (3·2CHCl3), 3 and 3·2H2O, [FeII(L4pyrimidine)2(NCS)2] (4), 4·H2O, [FeII(L4pyrimidine)2(NCSe)2] (5), 5·2MeOH, 5·1.5H2O, and [FeII(L4pyrimidine)2(NCBH3)2]·2.5H2O (6·2.5H2O). Single-crystal x-ray diffraction reveals that the N6-coordinated Fe(II) centers in 1, 2, 3·2CHCl3, 4, 5, and 5·2MeOH have two bidentate triazole ligands equatorially bound and two axial NCE co-ligands trans-coordinated. All structures are high spin (HS) at 100 K, except 3·2CHCl3, which is low spin (LS). Solid-state magnetic measurements show that only 3·2CHCl3 (T1/2 >400 K) and 5·1.5H2O (T1/2 = 110 K) undergo spin crossover (SCO); the others remain HS at 300-50 K. When 3·2CHCl3 is heated at 400 K it desorbs CHCl3 becoming 3, which remains HS at 400-50 K. UV-visible studies in CH2Cl2, CHCl3, Me2CO, MeCN, and CH3NO2 solutions for the BH3 analogs 3 and 6 led to a 6:1 ratio of Lnpyrimidine/Fe(II) being employed for the solution studies. These revealed SCO activity in all five solvents, with T1/2 values for the 2-pyrimidine complex (247-396 K) that were consistently higher than for the 4-pyrimidine complex (216-367 K), regardless of solvent choice, consistent with the 2-pyrimidine ring providing a stronger ligand field than the 4-pyrimidine ring. Strong correlations of solvent polarity index with the T1/2 values in those solvents are observed for each complex, enabling predictable T1/2 tuning by up to 150 K. While this correlation is tantalizing, here it may also be reflecting solvent-dependent speciation – so future tests of this concept should employ more stable complexes. Differences between solid-state (ligand field; crystal packing; solvent content) and solution (ligand field; solvation; speciation) effects on SCO are highlighted.

Inorganic Chemistry published new progress about Chemical speciation. 42839-08-7 belongs to class pyrimidines, name is Ethyl pyrimidine-2-carboxylate, and the molecular formula is C7H8N2O2, COA of Formula: C7H8N2O2.

Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia

Volkov, Oleg A. published the artcileSpecies-Selective Pyrimidineamine Inhibitors of Trypanosoma brucei S-Adenosylmethionine Decarboxylase, Application of 4-Chloro-6-isopropylpyrimidin-2-amine, the main research area is pyrimidineamine preparation trypanosomicide Trypanosoma adenosylmethionine decarboxylase inhibitor.

New therapeutic options are needed for treatment of human African trypanosomiasis (HAT) caused by protozoan parasite Trypanosoma brucei. S-Adenosylmethionine decarboxylase (AdoMetDC) is an essential enzyme in the polyamine pathway of T. brucei. Previous attempts to target this enzyme were thwarted by the lack of brain penetration of the most advanced series. Herein, the authors describe a T. brucei AdoMetDC inhibitor series based on a pyrimidineamine pharmacophore that the authors identified by target-based high-throughput screening. The pyrimidineamines showed selectivity for T. brucei AdoMetDC over the human enzyme, inhibited parasite growth in whole-cell assay, and had good predicted blood-brain barrier penetration. The medicinal chem. program elucidated structure-activity relationships within the series. Features of the series that were required for binding were revealed by determining the x-ray crystal structure of TbAdoMetDC bound to one analog. The pyrimidineamine series provides a novel starting point for an anti-HAT lead optimization.

Journal of Medicinal Chemistry published new progress about Blood-brain barrier. 73576-33-7 belongs to class pyrimidines, name is 4-Chloro-6-isopropylpyrimidin-2-amine, and the molecular formula is C7H10ClN3, Application of 4-Chloro-6-isopropylpyrimidin-2-amine.

Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia

Xiang, Yepeng published the artcileHalogen-induced internal heavy-atom effect shortening the emissive lifetime and improving the fluorescence efficiency of thermally activated delayed fluorescence emitters, Synthetic Route of 36847-11-7, the main research area is LED phenoxazine derivative thermally activated delayed fluorescence heavy atom.

Halogenation of an electron acceptor in TADF emitters is presented as a feasible strategy for shortening the DF lifetimes of TADF emitters without sacrificing their photoluminescence quantum yields. A greenish-yellow device based on the chloride-substituted emitter (ClPPM) achieves a high external quantum efficiency of 22.2% and an ultra-slow efficiency roll-off of 12.3% at a practical luminance of 1000 cd m-2, which is comparable to the state-of-the-art device performance for green-to-yellow TADF OLEDs at the practical luminance.

Journal of Materials Chemistry C: Materials for Optical and Electronic Devices published new progress about Bathochromic effect. 36847-11-7 belongs to class pyrimidines, name is 2,4,6-Tribromopyrimidine, and the molecular formula is C4HBr3N2, Synthetic Route of 36847-11-7.

Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia

Tang, Zhaocheng published the artcileCercosporin-bioinspired photoreductive activation of aryl halides under mild conditions, Formula: C4HBr3N2, the main research area is microbial fermentation arylation photocatalyst excited state organocatalysis.

Bioinspired by the naturally-occurring cercosporin-driven infection process of plant pathogenic fungi Cercospora sp., here we took advantage of the photophys. properties of cercosporin, and used it as a metal-free photocatalyst to develop an unprecedented cercosporin-driven photocatalysis under mild conditions. Furthermore, the forming conditions and excited-state dynamics of radical anions of cercosporin have been systematically investigated. In particular, transient femtosecond absorption spectroscopy was employed to unveil the excited-state dynamics of cercosporin, a key step that dictates its function in photocatalysis. We showed that cercosporin was able to be sufficiently activated through a two-step excitation, ultimately boosting its photocatalytic activity for the reductive activation of substrates with very low reactivity. Since large quantities of cercosporin can be easily produced through microbial fermentation like other com. available perylenequinonoid pigments, such as hypocrellin A and hypocrellin B, we expect that all advantages of these naturally-occurring perylenequinonoid pigments as green photocatalysts can be further explored to a wide range of synthetic transformations.

Journal of Catalysis published new progress about Arylation catalysts. 36847-11-7 belongs to class pyrimidines, name is 2,4,6-Tribromopyrimidine, and the molecular formula is C4HBr3N2, Formula: C4HBr3N2.

Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia

Ghosh, Indrajit published the artcileChromoselective Photocatalysis: Controlled Bond Activation through Light-Color Regulation of Redox Potentials, Recommanded Product: 2,4,6-Tribromopyrimidine, the main research area is photochem redox reaction potential catalyst bond activation; C−H arylation; dyes; photocatalysis; radical anions; radicals.

The authors report the light-color regulation of the redox potential of a photocatalyst to control the activation of chem. bonds. Light-color control of the redox power of a photocatalyst introduces a new selectivity parameter to photoredox catalysis: instead of changing the catalyst or ligand, alteration of the color of the visible-light irradiation adjusts the selectivity in catalytic transformations. By using this principle, the selective activation of aryl-halide bonds for C-H arylation and the sequential conversion of functional groups with different reduction potentials is possible by simply applying different colors of light for excitation of the photocatalyst.

Angewandte Chemie, International Edition published new progress about Arylation catalysts. 36847-11-7 belongs to class pyrimidines, name is 2,4,6-Tribromopyrimidine, and the molecular formula is C4HBr3N2, Recommanded Product: 2,4,6-Tribromopyrimidine.

Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia