Ketone Derivatives of Propargylamines as Synthetic Equivalents of Conjugated 2,4,1-Enynones in the Synthesis of Acetylenic 2-Pyrazolines and Pyrazoles

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.

Cyclization of arylhydrazones of cross-conjugated enynones: synthesis of luminescent styryl-1H-pyrazoles and propenyl-1H-pyrazoles

“…GC analysis of the reaction mixtures was performed on a Crystallux-4000M gas chromatograph (Russia) with a flame ionization detector using a 25 m capillary column (100% polydimethylsiloxane), under the conditions described in our previous work. 28…”

“…GC analysis of the reaction mixtures was performed on a Crystallux-4000M gas chromatograph (Russia) with a flame ionization detector using a 25 m capillary column (100% polydimethylsiloxane), under the conditions described in our previous work. 28 Elemental microanalysis for C, H and Si was carried out by express gravimetric methodology. Nitrogen was determined by the Dumas micromethod.…”

“…IR (KBr) cm −1 : 2214, 1647, 1628. MS (EI, 70 eV): m/z (%) = 136 (M + , 4), 121 (15), 109 (14), 108 (93), 107 (17), 96 (12), 95 (100), 94 (16), 93 (28), 91 (17), 80 (10), 79 (28), 77 (35), 69 (26), 68 (10), 67 (26), 66 (18), 65 (19), 53 (28), 41 (36), 40 (10), 39 (39), 38 (10). C 9 H 12 O (136.19): calcd C 79.37, H 8.88; found C 79.27, H 8.90.…”

“…19 F NMR (376 MHz, CDCl 3 ), δ ppm: −117.40. MS (EI, 70 eV): m/z (%) = 340 (M + , 36), 339 (60), 339 (34), 322 (30), 321 (100), 320 (24), 319 (28), 236 (10), 235 (10), 218 (12), 217 (14), 193 (10), 180 (15), 77 (43), 51 (15). C 23 H 17 FN 2 (340.40): calcd C 81.…”

“…19 F NMR (376 MHz, CDCl 3 ), δ ppm: −113.77. MS (EI, 70 eV): m/z (%) = 340 (M + , 60), 339 (100), 338 (22), 236 (14), 235 (11), 180 (28), 77 (35). C 23 H 17 FN 2 (340.40): calcd C 81.…”