hydrazine monohydrochloride readily formed pyrazoline intermediates under mild conditions. Oxidation of pyrazolines, in situ, employing bromine afforded a wide variety of pyrazoles. The methodology offers a fast, and often chromatography-free protocol for the synthesis of 3,4,5-substituted pyrazoles in good to excellent yields. Alternatively, a more benign oxidation protocol affords 3,5-disubstituted or
The diaza-Nazarov cyclization involving a 2,3-diaza-pentadienyl cation for the synthesis of polysubstituted pyrazoles
作者:Balakrishna Aegurla、Rama Krishna Peddinti
DOI:10.1039/c7ob01949a
日期:——
diaza-Nazarov (DAN) type cyclization for the construction of substituted pyrazoles from easily available starting materials via an enamine–iminium ion intermediate is described. The oxidative cyclization worked under green conditions with remarkable regioselectivity. This one-pot, efficient and operationally simple three-component intramolecular regioselective DAN cyclization displayed a wide range of
Some new 3,5-diaryl-1H-pyrazoles were prepared from aryl methyl ketones via Claisen condensation with aromatic esters and followed by cyclization with hydrazine monohydrate. Their structures were confirmed by IR, 1H NMR spectroscopy, mass spectrometry and elemental analysis. The X-ray structure for 3(5)-(4-tert-butylphenyl)-5(3)-(4-methoxyphenyl)-1H-pyrazole (2b) was presented. The results show that
一些新的3,5-二芳基-1 H-吡唑是由芳基甲基酮经克莱森与芳香族酯缩合制备的,然后与一水合肼环化。通过IR,1 H NMR光谱,质谱和元素分析确认了它们的结构。给出了3(5)-(4-叔丁基苯基)-5(3)-(4-甲氧基苯基)-1H-吡唑(2b)的X射线结构。结果表明,化合物2b以互变异构体I和II存在,其分子通过N–H··N分子间氢键连接,形成由互变异构体I和II组成的环状二聚体。
Monoamine Oxidase Isoform-Dependent Tautomeric Influence in the Recognition of 3,5-Diaryl Pyrazole Inhibitors
A series of 3,5-diaryl pyrazoles were prepared and assayed for their ability to inhibit reversibly monoamine oxidase-A (MAO-A) and monoamine oxidase B (MAO-B). Several compounds show inhibitory activity with concentration values in the nanomolar range. A computational work was carried out on the two most selective inhibitors that have tautomeric pyrazole forms. The binding free energies of these compounds for each MAO isoform were influenced by the tautomeric equilibria.