3-羟基哒嗪及其CH3, NO2和Cl取代衍生物质子转移过程的理论研究

用密度泛函理论(DFT) B3LYP方法, 在6-311＋G*基组下, 对3-羟基哒嗪及其CH₃, NO₂和Cl取代衍生物分子醇式和酮式结构互变异构化反应进行了研究, 优化化合物的几何构型, 寻找反应的过渡态, 通过振动分析和内禀反应坐标(IRC)分析加以证实, 计算了反应的活化能. 结果表明, 3(2H)-哒嗪酮及其带取代基的衍生物不论是单体, 还是相对应的二聚体, 比其相对应的异构体能量低, 表明在通常情况下是以3(2H)-哒嗪酮及其衍生物形式稳定存在的, 这与前人通过实验数据对3-羟基哒嗪互变异构体的比率进行预测的结果是一致的. 根据计算结果讨论了异构化反应的机理.     

3-羟基哒嗪及其CH3，NO2和Cl取代衍生物质子转移过程的理论研究

用密度泛函理论(DFT)B3LYP方法,在6-311 G*基组下,对3-羟基哒嗪及其CH3,NO2和Cl取代衍生物分子醇式和酮式结构互变异构化反应进行了研究,优化化合物的几何构型,寻找反应的过渡态,通过振动分析和内禀反应坐标(IRC)分析加以证实,计算了反应的活化能.结果表明,3(2H)-哒嗪酮及其带取代基的衍生物不论是单体,还是相对应的二聚体,比其相对应的异构体能量低,表明在通常情况下是以3(2H)-哒嗪酮及其衍生物形式稳定存在的,这与前人通过实验数据对3-羟基哒嗪互变异构体的比率进行预测的结果是一致的.根据计算结果讨论了异构化反应的机理.     

Synthesis and Properties of 6,7,8-Substituted 2-(4-Oxo-3,4-dihydro-2-quinazolinyl)acetonitriles

2-(4-Oxo-3,4-dihydro-2-quinazolinyl)acetonitriles have been obtained by the interaction of -cyanoethylthioiminoacetate with substituted anthranilic acids. Prototropy became apparent in the series of synthesized compounds. Reactions of the 2-(4-oxo-3,4-dihydro-2-quinazolinyl)acetonitriles have been carried out with (hetero)aromatic aldehydes leading to the formation of 3-aryl-2-(4-oxo-3,4-dihydro-2-quinazolinyl)acrylonitriles.     

Catalyst‐ and solvent‐free synthesis of 2‐fluoro‐N‐(3‐methylsulfanyl‐1H‐1,2,4‐triazol‐5‐yl)benzamide through a microwave‐assisted Fries rearrangement: X‐ray structural and theoretical studies

An efficient approach for the regioselective synthesis of (5‐amino‐3‐methylsulfanyl‐1H‐1,2,4‐triazol‐1‐yl)(2‐fluorophenyl)methanone, C₁₀H₉FN₄OS, (3), from the N‐acylation of 3‐amino‐5‐methylsulfanyl‐1H‐1,2,4‐triazole, (1), with 2‐fluorobenzoyl chloride has been developed. Heterocyclic amide (3) was used successfully as a strategic intermediate for the preparation of 2‐fluoro‐N‐(3‐methylsulfanyl‐1H‐1,2,4‐triazol‐5‐yl)benzamide, C₁₀H₉FN₄OS, (4), through a microwave‐assisted Fries rearrangement under catalyst‐ and solvent‐free conditions. Theoretical studies of the prototropy process of (1) and the Fries rearrangement of (3) to provide (4), involving the formation of an intimate ion pair as the key step, were carried out by density functional theory (DFT) calculations. The crystallographic analysis of the intermolecular interactions and the energy frameworks based on the effects of the different molecular conformations of (3) and (4) are described.     

Experimental (FT‐IR) and theoretical (DFT) studies on prototropy and H‐bond formation for pyrazine‐2‐amidoxime

The results of the first structural studies (with the use of both experimental and theoretical methods) on pyrazine‐2‐amidoxime (PAOX) were shown and discussed. FT‐IR spectra were recorded in different concentrations of the PAOX in apolar solvent to check the possibility of the inter‐ or intramolecular hydrogen‐bond formation. All possible tautomers–rotamers of PAOX were then theoretically considered at the DFT(B3LYP)/6‐311+G** level in vacuo. For selected isomers, calculations were also performed at higher levels of theory {B3LYP/6‐311+G(3df,2p) and G3B3}. Based on the results of DFT calculations, the most stable isomers were found, and their total free energies and infrared spectra were calculated. The energy variation plots for the N8?C7?N9?O10 and N1?C2?C7?N9 dihedral angles were also computed to find two energy barriers, one for E/Z isomerization around the C7?N9 double bond and the other one for rotation of the pyrazinyl ring around the C2?C7 single bond. The results show that the stability of the PAOX isomers strongly depend on their configuration and orientation of the substituents. The possibilities of inter‐ and intramolecular hydrogen bonds were also experimentally and theoretically checked. Finally, a potential of mean force was determined in CHCl₃ for a dimer of PAOX with hexamethylphosphoramide. Both, experimental and theoretical results are in agreement. Copyright © 2016 John Wiley & Sons, Ltd.     

Heterocyclic Analogs of Pleiadiene. 72. Sulfones of Perimidine and 2,3-Dihydroperimidine. Synthesis and Some Properties

The arenesulfonation of perimidines has been carried out in polyphosphoric acid and found to occur at the 6(7) and 4(9) positions. Reduction then gave the first representatives of 2,3-dihydroperimidine sulfones. We report a comparative ¹H NMR spectroscopic analysis of the arenesulfonyl- and acylperimidines together with their annular prototropic tautomerism.     

3-羟基哒嗪及其CH3,NO2和CI取代衍生物质子转移过程的理论研究

用密度泛函理论(DFT)B3LYP方法,在6-311+G*基组下,对3-羟基哒嗪及其CH3,NO2和Cl取代衍生物分子醇式和酮式结构互变异构化反应进行了研究,优化化合物的几何构型,寻找反应的过渡态,通过振动分析和内禀反应坐标(IRC)分析加以证实,计算了反应的活化能.结果表明,3(2H)-哒嗪酮及其带取代基的衍生物不论是单体,还是相对应的二聚体,比其相对应的异构体能量低,表明在通常情况下是以3(2H)-哒嗪酮及其衍生物形式稳定存在的,这与前人通过实验数据对3-羟基哒嗪互变异构体的比率进行预测的结果是一致的.根据计算结果讨论了异构化反应的机理.