Novel biocompatible glucose-based deep eutectic solvent as recyclable medium and promoter for expedient multicomponent green synthesis of diverse three and four substituted pyrazole-4-carbonitrile derivatives
A novel biocompatible glucose-based deep eutectic solvent (DES) is reported for the first time in the multicomponent synthesis of diverse three and four substituted pyrazole-4-carbonitrile derivatives under catalyst-free condition without using any harmful organic solvent even for purification of the products. The desired products were obtained with high degree of diversity from the reaction of malononitrile
The conversion of isothiazoles into pyrazoles using hydrazine
作者:Heraklidia A. Ioannidou、Panayiotis A. Koutentis
DOI:10.1016/j.tet.2009.06.041
日期:2009.8
The conversion of isothiazoles into pyrazoles on treatment with hydrazine is investigated. The influence of various C-3, C-4 and C-5 isothiazole substituents and some limitations of this ring transformation are examined. When the isothiazole C-3 substituent is a good nucleofuge, 3-aminopyrazoles are obtained. However, when the 3-substituent is not a leaving group it is retained in the pyrazole product. Treatment of 4-bromo-3-chloro-5-phenylisothiazoie 56 or 3-chloro-4,5-diphenylisothiazole 57 with anhydrous hydrazine at ca. 200 degrees C for a few minutes gives the corresponding 3-hydrazinoisothiazoles 61 and 64 respectively in high yields; the stability of these new hydrazines is investigated. 5,5'-Diphenyl-3,3'-biisothiazole-4,4'-dicarbonitrile 78 reacts with hydrazine to give 5,5'-diphenyl-3,3'-bi(1H-pyi-azole)-4,4'-dicarbonitrile 79. Methylhydrazine reacts with 3-chloro-5-phenytisothiazole-4-carbonitrile 1 to give 3-(1-methylhydrazino)-5-phenylisothiazole-4-carbontrile 83 and 3-amino-lmethyl-5-phenylpyrazole-4-carbonitrile 84. All products are fully characterised and rational mechanisms for the isothiazole into pyrazole transformation are proposed. (C) 2009 Elsevier Ltd. All rights reserved.
——
作者:Xiao-Hong Zhang、Lin-Hong Weng、Gui-Yu Jin
DOI:10.1023/a:1013224308504
日期:——
The title compound 1-(1',3'-dimethyl-5'-chloropyrazol-4'-carbonyl)-3-(2'-chlorophenyl)-5-amino-4-cyanopyrazole (C16H12Cl2N6O) has been synthesized and characterized by X-ray diffraction: Triclinic, space group P1, with a = 8.6712(8) Angstrom, b = 9.5091(10) Angstrom, c = 11.2170(11) Angstrom; alpha = 71.531(2), beta = 84.683(2), gamma = 74.099(2); Z = 2; V = 843.7(14) Angstrom(3). C(10), O(1), C(11), and N(2) atoms are coplanar with the average deviation of 0.0071Angstrom, which form 11.03degrees and 43.93degrees dihedral angles with pyrazole planes (I) and (II), respectively.