No abstract

No abstract

Please cite this article as: Nikitina PA, Peregudov AS, Koldaeva TY, Kuz'mina LG, Adiulin EI, Tkach II, Perevalov VP, Synthesis and study of prototropic tautomerism of 2-(2-hydroxyphenyl)-1-hydroxyimidazoles, Tetrahedron (2015), Novel 2-(2-hydroxyphenyl) substituted imidazoles have been synthesized. A prototropic tautomerism of the 1-hydroxyimidazole derivatives has been studied. X-ray diffraction analysis and IR-spectroscopy have revealed that in the solid state the title compounds exist as the Nhydroxy tautomers. The 1 H and 13 C NMR spectra of the new imidazole derivatives are discussed. It has been shown that in chloroform solutions 5-carbonylsubstituted 2-(2-hydroxyphenyl)-1-hydroxyimidazoles exist in the N-hydroxy tautomeric form. A transition to DMSO results in the existence of the 1-hydroxyimidazoles under study as the N-oxide tautomers.

No abstract

The reactions of 2 chloro 1 cyano 1 diethoxyphosphoryl 2 trifluoromethylethylene (2a) and 2 chloro 2 chlorodifluoromethyl 1 cyano 1 diethoxyphosphorylethylene (2b) with arylamines, arylhydrazines, amidines, 2 aminopyridines, and 5 aminopyrazoles were studied. Alkenes 2a,b can serve as precursors of aminopyrazoles, pyrimidines, pyrido[1,2 a]pyrimidines, and pyrazolo[1,5 a]pyrimidines modified with the fluoroalkyl and diethoxyphosphoryl groups. Intermediates of some heterocyclization reactions were detected by NMR spectroscopy. The structures of the compounds were confirmed by X ray diffraction analysis.Key words: 2 chloro 1,1 dicyano 2 trifluoromethylethylene, 2 chloro 1 cyano 1 di ethoxyphosphoryl 2 trifluoromethylethylene, 2 chloro 2 chlorodifluoromethyl 1 cyano 1 diethoxyphosphorylethylene, aminopyrazoles, pyrimidines, pyrido[1,2 a]pyrimidines, pyr azolo[1,5 a]pyrimidines, heterocyclization, X ray diffraction analysis. Scheme 1 X = F (a), Cl (b)Reactions of polyfluoroalkyl vinylphosphonates derivatives 2a and 2b followed by elimination of hydrogen chloride to form enamines 3 and 4, respectively. Scheme 2Unlike alkenes 2a and 2b existing as mixtures of two stereoisomers (readily interconvertable), enamines 3 and 4 derived from these compounds exist exclusively as the Z isomer, which is, apparently, thermodynamically more stable due to intramolecular hydrogen bonding. The for mation of the Z isomers and the presence of a hydrogen bond were confirmed by the results of X ray diffraction analysis of compound 3b and NMR spectroscopic stud ies. The 19 F NMR spectra of compounds 3 and 4 have a singlet with a width at half height of 1 Hz. It is known 4 that the cis arrangement of the trifluoromethyl and phosphonate groups is characterized by 4 J F,P = 2.0 Hz. Consequently, the trifluoromethyl and phosphonate groups in compounds 3 and 4 are in the trans arrangement.