Togliatti State University, 14 Belorusskaya Str., 445020 Togliatti, Russia.
J Org Chem. 2022 May 6;87(9):5916-5924. doi: 10.1021/acs.joc.2c00198. Epub 2022 Apr 8.
An interaction of 1,5-diaryl-3-X-pent-4-yn-1-ones (where X stands for piperidin-1-yl, morpholin-4-yl, 4-methylpiperazin-1-yl) with arylhydrazines proceeds at room temperature and results in 3-aryl-5-arylethynyl-1-phenyl-4,5-dihydro-1-pyrazoles with up to 57-73% yields. Under similar conditions, the cyclocondensation of conjugated 2,4,1-enynones with arylhydrazine proceeds only in the presence of cyclic amines. 1,5-Diaryl-3-X-pent-4-yn-1-ones are reported as synthetic equivalents of conjugated 2,4,1-enynones in reactions with arylhydrazines. On the basis of obtained data, there are highly efficient methods developed for the synthesis of 5-arylethynyl-substituted 4,5-dihydro-1-pyrazoles, as well as for similarly structured 1-pyrazoles prepared by oxidation in AcOH. Presented products possess quite marked fluorescent abilities. Emission maximum wavelengths are located at 453-465 and 363-400 nm, respectively; certain compounds show extremely large Stokes shifts that may reach 91,000 cm.
1,5-二芳基-3-X-戊-4-炔-1-酮（其中 X 代表哌啶-1-基、吗啉-4-基、4-甲基哌嗪-1-基）与芳基腙在室温下反应，生成高达 57-73%收率的 3-芳基-5-芳基乙炔基-1-苯基-4,5-二氢-1-吡唑。在类似条件下，共轭 2,4,1-烯炔与芳基腙的环缩合仅在环状胺存在下进行。1,5-二芳基-3-X-戊-4-炔-1-酮被报道为与芳基腙反应的共轭 2,4,1-烯炔的合成等价物。基于获得的数据，开发了高效的方法来合成 5-芳基乙炔基取代的 4,5-二氢-1-吡唑，以及在 AcOH 中氧化制备的类似结构的 1-吡唑。所展示的产物具有相当明显的荧光能力。发射最大值波长分别位于 453-465nm 和 363-400nm 处；某些化合物表现出非常大的斯托克斯位移，可达 91000cm。
