Nano α-Al 2 O 3 supported ammonium dihydrogen phosphate (NH 4 H 2 PO 4 /Al 2 O 3 ): preparation, characterization and its application as a novel and heterogeneous catalyst for the one-pot synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3-c]pyrazole derivatives
2014; Royal Society of Chemistry; Volume: 4; Issue: 81 Linguagem: Inglês
10.1039/c4ra07813f
ISSN2046-2069
AutoresBehrooz Maleki, Samaneh Sedigh Ashrafi,
Tópico(s)Synthesis and biological activity
ResumoA simple, efficient, and environmentally benign route was developed for the preparation of 2-amino-3-cyano-4-aryl-7,7-dimethyl-5,6,7,8-tetrahydrobenzo[b]pyrans and 6-amino-5-cyano-4-aryl-1,4-dihydropyrano[2,3-c]pyrazoles from the condensation of various aldehydes, malononitrile, and 1,3-dicarbonyl compounds (1,3-cyclohexanedione or 5,5-dimethyl-1,3-cyclohexanedione) or 3-methyl-1-phenyl-2-pyrazoline-5-one, using NH4H2PO4/Al2O3 with good yields. The use of easily available catalyst, shorter reaction times, better yields, the simplicity of the reaction, the heterogeneous system, and the easy work up are the advantages of the present method. Characterization of the catalyst was performed by FT-IR spectroscopy, X-ray diffraction (XRD) techniques, thermal analysis (TG/DTG) and Transmission electron microscopy (TEM).
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