l-Proline as an efficicent catalyst for the multi-component synthesis of 6-amino-4-alkyl/aryl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles in water
作者:Hormi Mecadon、Md. Rumum Rohman、Iadeishisha Kharbangar、Badaker M. Laloo、Icydora Kharkongor、Mantu Rajbangshi、Bekington Myrboh
DOI:10.1016/j.tetlet.2011.04.048
日期:2011.6
An efficient four-component synthesis of 6-amino-4-alkyl/aryl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles involving ethyl acetoacetate, hydrazine hydrate, malononitrile, and various aldehydes using L-proline (10 mol %) in water under mild reaction condition in excellent yields is established. A comparative study of L-proline with gamma-alumina, basic alumina, and KF-alumina was also carried out. The generality and functional tolerance of this convergent and environmentally benign method is demonstrated. (C) 2011 Elsevier Ltd. All rights reserved.
γ-Alumina as a recyclable catalyst for the four-component synthesis of 6-amino-4-alkyl/aryl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles in aqueous medium
gamma-Alumina as an expedient and recyclable catalyst for the synthesis of 6-amino-4-alkyl/aryl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles in water via a four-component reaction is established. Comparative study of the efficacy of gamma-alumina, basic alumina and KF-alumina is also discussed. The method presented is mild, environment friendly, inexpensive and functionality tolerable to give the products in good to excellent yields. (C) 2011 Elsevier Ltd. All rights reserved.