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A catalyst-free, additive-free, and eco-friendly method for synthesizing 1,2,4-triazolo[1,5-a]pyridines under microwave conditions has been established. This tandem reaction involves the use of enaminonitriles and benzohydrazides, a transamidation mechanism followed by nucleophilic addition with nitrile, and subsequent condensation to yield the target compound in a short reaction time. The methodology demonstrates a broad substrate scope and good functional group tolerance, resulting in the formation of products in good-to-excellent yields. Furthermore, the scale-up reaction and late-stage functionalization of triazolo pyridine further demonstrate its synthetic utility. A plausible reaction pathway, based on our findings, has been proposed.

Pyridazine derivatives hold significant interest due to their broad applications in pharmaceuticals and materials science, where they serve as valuable scaffolds for bioactive compounds and functional materials. Here, we report a formal [4 + 2] reaction for the synthesis of 5’-sulfonyl-4’-aryl-3-cyano substituted pyridazine compounds from the reaction between vinylogous enaminonitriles and sulfonyl hydrazides. The key features of our pyridazine synthesis include the transamidation of vinylogous enaminonitriles with sulfonyl hydrazide, radical sulfonylation of the resulting intermediate, and subsequent 6-endo-trig radical cyclization. This reaction proceeds smoothly to deliver a series of pyridazine derivatives in good to high yields. We also found that the sulfonyl group of the synthesized pyridazines can be transformed into C-, O-, or N-containing functional groups. A gram-scale experiment and a diverse transformation of synthesized pyridazines were also performed to validate the practicality of our developed process. In the synthesis of sulfonyl-substituted pyridazines, a 6-endo-trig cyclization via a radical pathway is both kinetically and thermodynamically favored over the cyclization via an ionic pathway, as supported by DFT calculations. Pyridazine is an aromatic heterocyclic compound that is utilized as a bioisostere for benzene or pyridine, and is found in the core scaffold of various drug molecules, making synthetic methods to access pyridazine scaffolds of high interest. Here, the authors report the synthesis of 5’-sulfonyl-4’-aryl-3-cyano substituted pyridazine compounds from a formal [4 + 2] reaction between vinylogous enaminonitriles and sulfonyl hydrazides.

In continuation of studies for α-MSH stimulated melanogenesis inhibitors, we have evaluated the design, synthesis, and activity of a new series of chlorogenic acid (CGA) analogues comprising pyridine, pyrimidine, and diacyl derivatives. Among nineteen synthesized compounds, most of them (fifteen) exhibited better inhibitions of melanin formation in B16 melanoma cells. The results illustrated that a pyridine analogue 6f and a diacyl derivative 13a of CGA showed superior inhibition profiles (IC50: 2.5 ± 0.7 μM and 1.1 ± 0.1 μM, respectively) of α-MSH activities than positive controls, kojic acid and arbutin (IC50: 54 ± 1.5 μM and 380 ± 9.5 μM, respectively). The SAR studies showed that both –CF3 and –Cl groups exhibited better inhibition at the meta position on benzylamine than their ortho and para positions. In addition, the stability of diacyl analogues of CGA in methanol monitored by HPLC for 28 days indicated the steric bulkiness of acyl substituents as a key factor in their stability.

This study presents soil-moisture calibrations using low-frequency (15-40 MHz) time domain reflectometry (TDR) probe, referred to as water content reflectometer (WCR), for measuring the volumetric water content of landfill cover soils, developing calibrations for 28 different soils, and evaluating how WCR calibrations are affected by soil properties and electrical conductivity. A 150-mm-diameter PVC cell was used for the initial WCR calibration. Linear and polynomial calibrations were developed for each soil. Although the correlation coefficients (R2) for the polynomial calibration are slightly higher, the linear calibrations are accurate and pragmatic to use. The effects of soil electrical conductivity and index properties were investigated using the slopes of linear WCR calibrations. Soils with higher electrical conductivity had lower calibration slopes due to greater attenuation of the signal during transmission in the soil. Soils with higher electrical conductivity tended to have higher clay content, organic matter, liquid limit, and plasticity index. The effects of temperature and dry unit weight on WCR calibrations were assessed in clayey and silty soils. The sensor period was found to increase with the temperature and density increase, with greater sensitivity in fine-textured plastic soils. For typical variations in temperature, errors in volumetric water content on the order of 0.04 can be expected for wet soils and 0.01 for drier soils if temperature corrections are not applied. Errors on the order of 0.03 (clays) and 0.01 (silts) can be expected for typical variations in dry unit weight (± 2 kN/m3).

A catalyst-free, additive-free, and eco-friendly method for synthesizing 1,2,4-triazolo[1,5-a]pyridines under microwave conditions has been established. This tandem reaction involves the use of enaminonitriles and benzohydrazides, a transamidation mechanism followed by nucleophilic addition with nitrile, and subsequent condensation to yield the target compound in a short reaction time. The methodology demonstrates a broad substrate scope and good functional group tolerance, resulting in the formation of products in good-to-excellent yields. Furthermore, the scale-up reaction and late-stage functionalization of triazolo pyridine further demonstrate its synthetic utility. A plausible reaction pathway, based on our findings, has been proposed.A catalyst-free, additive-free, and eco-friendly method for synthesizing 1,2,4-triazolo[1,5-a]pyridines under microwave conditions has been established. This tandem reaction involves the use of enaminonitriles and benzohydrazides, a transamidation mechanism followed by nucleophilic addition with nitrile, and subsequent condensation to yield the target compound in a short reaction time. The methodology demonstrates a broad substrate scope and good functional group tolerance, resulting in the formation of products in good-to-excellent yields. Furthermore, the scale-up reaction and late-stage functionalization of triazolo pyridine further demonstrate its synthetic utility. A plausible reaction pathway, based on our findings, has been proposed.

Organocatalysts are abundantly used for various transformations, particularly to obtain highly enantio- and diastereomeric pure products by controlling the stereochemistry. These applications of organocatalysts have been the topic of several reviews. Organocatalysts have emerged as one of the very essential areas of research due to their mild reaction conditions, cost-effective nature, non-toxicity, and environmentally benign approach that obviates the need for transition metal catalysts and other toxic reagents. Various types of organocatalysts including amine catalysts, Brønsted acids, and Lewis bases such as N-heterocyclic carbene (NHC) catalysts, cinchona alkaloids, 4-dimethylaminopyridine (DMAP), and hydrogen bond-donating catalysts, have gained renewed interest because of their regioselectivity. In this review, we present recent advances in regiodivergent reactions that are governed by organocatalysts. Additionally, we briefly discuss the reaction pathways of achieving regiodivergent products by changes in conditions such as solvents, additives, or the temperature.

Pyridazine derivatives hold significant interest due to their broad applications in pharmaceuticals and materials science, where they serve as valuable scaffolds for bioactive compounds and functional materials. Here, we report a formal [4 + 2] reaction for the synthesis of 5'-sulfonyl-4'-aryl-3-cyano substituted pyridazine compounds from the reaction between vinylogous enaminonitriles and sulfonyl hydrazides. The key features of our pyridazine synthesis include the transamidation of vinylogous enaminonitriles with sulfonyl hydrazide, radical sulfonylation of the resulting intermediate, and subsequent 6-endo-trig radical cyclization. This reaction proceeds smoothly to deliver a series of pyridazine derivatives in good to high yields. We also found that the sulfonyl group of the synthesized pyridazines can be transformed into C-, O-, or N-containing functional groups. A gram-scale experiment and a diverse transformation of synthesized pyridazines were also performed to validate the practicality of our developed process. In the synthesis of sulfonyl-substituted pyridazines, a 6-endo-trig cyclization via a radical pathway is both kinetically and thermodynamically favored over the cyclization via an ionic pathway, as supported by DFT calculations.Pyridazine derivatives hold significant interest due to their broad applications in pharmaceuticals and materials science, where they serve as valuable scaffolds for bioactive compounds and functional materials. Here, we report a formal [4 + 2] reaction for the synthesis of 5'-sulfonyl-4'-aryl-3-cyano substituted pyridazine compounds from the reaction between vinylogous enaminonitriles and sulfonyl hydrazides. The key features of our pyridazine synthesis include the transamidation of vinylogous enaminonitriles with sulfonyl hydrazide, radical sulfonylation of the resulting intermediate, and subsequent 6-endo-trig radical cyclization. This reaction proceeds smoothly to deliver a series of pyridazine derivatives in good to high yields. We also found that the sulfonyl group of the synthesized pyridazines can be transformed into C-, O-, or N-containing functional groups. A gram-scale experiment and a diverse transformation of synthesized pyridazines were also performed to validate the practicality of our developed process. In the synthesis of sulfonyl-substituted pyridazines, a 6-endo-trig cyclization via a radical pathway is both kinetically and thermodynamically favored over the cyclization via an ionic pathway, as supported by DFT calculations.

This study explored differences in frontal white-matter (WM) integrity between methamphetamine (MA) abusers and healthy comparison subjects using diffusion tensor imaging (DTI). Fractional anisotropy (FA) values, which indicate WM integrity, were calculated for regions-of-interest in frontal WM on diffusion tensor images of 32 MA abusers and 30 healthy comparison subjects. Frontal executive functions were also assessed by the Wisconsin Card Sorting test (WCST). MA abusers had significantly lower FA values in bilateral frontal WM at the anterior commissure–posterior commissure (AC–PC) plane and the right frontal WM 5 mm above the AC–PC plane relative to healthy comparison subjects. MA abusers had more total, perseveration and non-perseveration errors in the WCST relative to healthy comparison subjects. FA values of the right frontal WM 5 mm above the AC–PC plane negatively correlated with the number of total and non-perseveration errors in the WCST in MA abusers. In the sub-analysis for gender differences, lower FA values in frontal WM and more errors in the WCST were found only in male MA abusers, not in female MA abusers, relative to comparison subjects of the respective gender. We report that frontal WM integrity of MA abusers is compromised. This finding may also be related to impairment in frontal executive function. In addition, the neurotoxic effect of MA on frontal WM may be less prominent in women than in men, possibly due to oestrogen's neuroprotective effect.

We theoretically study Fano resonance in a two-level quantum dot side-coupled to two leads, which are connected by a direct channel. The resonance lineshape is found to be deformed, from the conventional Fano form, by interlevel Coulomb interaction and interlevel interference. We derive the connection between the lineshape deformation and the interaction-induced nonmonotonicity of level occupation, which may be useful for experimental study. The dependence of the lineshape on the transmission of the direct channel and on the dot-lead coupling matrix elements is discussed.