UV-induced E/Z isomerization of the electron-rich pyrrole ring containing diketoenols: Theoretical and experimental study

IF 2.1 3区化学 Q2 CHEMISTRY, ORGANIC

Tetrahedron Pub Date : 2024-10-09 DOI:10.1016/j.tet.2024.134292

Mark V. Sigalov , Bagrat A. Shainyan , Nina N. Chipanina , Larisa P. Oznobikhina

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Abstract

The Knoevenagel reaction of 2-acetyl-1,3-indandione, dehydroacetic acid, 3-acetyl-4-hydroxy-coumarin and acetyl-barbituric acid with pyrrol-2-carbaldehyde affords 2-(1-hydroxy-3-(1H-pyrrol-2-yl)allylidene)-1H-indene-1,3(2H)-dione 5, 3-(3-(1H-pyrrol-2-yl)acryloyl)-4-hydroxy-6-methyl-2H-pyran-2-one 6, 3-(3-(1H-pyrrol-2-yl)acryloyl)-4-hydroxy-2H-chromen-2-one 7 and 5-(1-hydroxy-3-(1H-pyrrol-2-yl)allylidene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione 8. The UV-induced E→Z isomerization, intra and intermolecular H-bonding is studied by NMR, IR, UV spectroscopy and theoretical calculations. The driving force for the E→Z isomerization is the formation of a bifurcate O–H⋯O⋯H–N hydrogen bond in the latter. The position of the E⇆Z equilibrium strongly depends on the solvent (CH₂Cl₂, acetone, EtOH, DMSO). According to QTAIM analysis, the formed OH⋯O bonds are strong or moderate in energy (from 7.6 to 10.2 kcal/mol), while the NH⋯O bonds are weak (from 4.8 to 6.4 kcal/mol).

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紫外线诱导的含二酮烯醇的富电子吡咯环的 E/Z 异构化：理论和实验研究

2-acetyl-1,3-indandione, dehydroacetic acid, 3-acetyl-4-hydroxy-coumarin and acetyl-barbituric acid 与 pyrrol-2-carbaldehyde 的 Knoevenagel 反应生成 2-(1-hydroxy-3-(1H-pyrrol-2-yl)allylidene)-1H-indene-1,3(2H)-dione 5、3-(3-(1H-pyrrol-2-yl)acryloyl)-4-hydroxy-6-methyl-2H-pyran-2-one 6, 3-(3-(1H-pyrrol-2-yl)acryloyl)-4-hydroxy-2H-chromen-2-one 7 and 5-(1-hydroxy-3-(1H-pyrrol-2-yl)allylidene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione 8.通过核磁共振、红外光谱、紫外光谱和理论计算研究了紫外线诱导的 E→Z 异构化、分子内和分子间 H 键作用。E→Z 异构化的驱动力是在后者中形成一个分叉的 O-H⋯O⋯H-N 氢键。E⇆Z 平衡的位置在很大程度上取决于溶剂（CH2Cl2、丙酮、EtOH、DMSO）。根据 QTAIM 分析，形成的 OH⋯O 键能量较强或中等（从 7.6 到 10.2 kcal/mol），而 NH⋯O 键能量较弱（从 4.8 到 6.4 kcal/mol）。

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来源期刊

Tetrahedron 化学-有机化学

CiteScore

3.90

自引率

4.80%

发文量

439

审稿时长

34 days

期刊介绍： Tetrahedron publishes full accounts of research having outstanding significance in the broad field of organic chemistry and its related disciplines, such as organic materials and bio-organic chemistry. Regular papers in Tetrahedron are expected to represent detailed accounts of an original study having substantially greater scope and details than that found in a communication, as published in Tetrahedron Letters. Tetrahedron also publishes thematic collections of papers as special issues and ''Reports'', commissioned in-depth reviews providing a comprehensive overview of a research area.