Iron(III) phthalocyanine chloride-catalyzed oxidation–aromatization of α,β-unsaturated ketones with hydrazine hydrate: Synthesis of 3,5-disubstituted 1H-pyrazoles
We have developed an iron(III) phthalocyanine chloride-catalyzed oxidation–aromatization of α,β-unsaturated ketones with hydrazine hydrate. Various 3,5-disubstituted 1H-pyrazoles were obtained in good to excellent yields. This method offers several advantages, including room-temperature conditions, short reaction time, high yields, simple work-up procedure, and use of air as an oxidant. The catalyst
been developed for the synthesis of pyrazole. Based on the analysis of UV‐Vis absorption of the substrate, the reaction was designed to avoid the use of external photocatalysis and proceeds via direct irradiation of N‐centred anion by sunlight. The key features of this reaction include operational simplicity, readily available reagents, and amenability to gram‐scale synthesis.
A new process for synthesis of 5-aryl-3-phenylpyrazole is achieved. The regioselective ring-opening reaction of 2-aryl-3-benzoyl-1,1-cyclopropanedicarbonitrile with hydrazine plays a crucial role in the described process.
An Efficient One-Pot Synthesis of 3,5-Disubstituted 1H-Pyrazoles
作者:Hua Chen、Lei-Lei Wu、Yi-Cen Ge、Ting He、Lei Zhang、Xing-Li Fu、Hai-Yan Fu、Rui-Xiang Li
DOI:10.1055/s-0031-1290772
日期:2012.5
An efficient, general, one-pot, three-component procedure for the preparation of 3,5-disubstituted 1H-pyrazoles via condensation of substituted aromatic aldehydes, tosylhydrazine and terminal alkynes in toluene is reported. The reaction tolerates a variety of functional groups and sterically hindered substrates to afford the desired pyrazoles in yields of 67-91%.