RESUMEN
A facile one-pot cascade synthesis involving simultaneous in situ pyrazole formation followed by iodine/DMSO-mediated oxidation has been established to afford 1-aryl-2-(3-aryl)-1H-pyrazol-5-yl-ethane-1,2-diones. Primarily, a two-pot approach has been established which includes the reaction of 3-methylthio-1,5-diaryl-2-pentene-1,5-diones with hydrazine in the first step to afford pyrazole, which was eventually oxidized in the next steps in the presence of iodine in DMSO. Furthermore, we performed both steps in the same pot to afford 1,2-dicarbonyl compounds in good yield. The structure of one of the compounds was confirmed by single crystal X-ray analysis. DMSO served as a solvent as well as an oxidant. Moreover, N-substituted hydrazines provided 1-(1-substituted-3-aryl-1H-pyrazol-5-yl)-2-arylethane-1,2-diones regioselectively. Furthermore, for synthetic application, 1-aryl-2-(3-aryl)-1H-pyrazol-5-yl-ethane-1,2-diones were treated with o-phenylenediamine to afford pyrazole-functionalized quinoxaline in good yield. A control reaction was carried out to understand the mechanism of product formation.
RESUMEN
A simple and efficient base-mediated [3 + 3] cyclization of 1,3-dianionic ketones with 3,3-bis(methylthio)-1-arylprop-2-en-1-ones was developed to afford 3-hydroxy-biaryls, hydroxy-xylenes, and hydroxy-teraryls. Various tri- and tetra-substituted phenols were prepared from different symmetric and asymmetric ketones. The reaction of 2-(bis(methylthio)methylene)-3,4-dihydronaphthalen-1(2H)-ones with different ketones provided 1-(methylthio)-9,10-dihydrophenanthren-3-ols in very good yield. The scope of the reaction was further extended by the synthesis of cyclopropyl-functionalized phenols. One of the compounds was crystallized, and its structure was confirmed using the single-crystal X-ray approach.
RESUMEN
The binding studies of calix[4]pyrroles (1-6) with fluoro, chloro, bromo, iodo and sulphato anions generated from normal-tetrabutylammoniumfluoride, normal-tetrabutylammoniumchloride, normal-tetrabutylammoniumbromide, normal-tetrabutylammoniumiodide, and normal-tetrabutylammoniumsulphate respectively were investigated by electrospray ionization mass spectrometry (ESI-MS) in dichloromethane-acetonitrile in negative ion mode. The efficacy of a particular calix[4]pyrrole to bind with anions was found maximum at low cone voltage of the instrument, at high cone voltage the binding was suppressed due to removal of anion from the cavity of the macrocycles. The binding strength was found inversely proportional to the size of anion for a particular calix[4]pyrrole. The fragmentation pattern of calix[4]pyrrole was observed at higher cone voltage of ESI-MS and was interpreted. The association constants of calix[4]pyrroles and anions obtained from electronic transition studies were in good agreement with that observed from (1)H NMR titration studies.
