Odin IS, Chertov AY, Grigor'eva OB, Golovanov AA. Ketone Derivatives of Propargylamines as Synthetic Equivalents of Conjugated 2,4,1-Enynones in the Synthesis of Acetylenic 2-Pyrazolines and Pyrazoles.
J Org Chem 2022;
87:5916-5924. [PMID:
35394780 DOI:
10.1021/acs.joc.2c00198]
[Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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-1H-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-1H-pyrazoles, as well as for similarly structured 1H-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.
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