A highlyregioselectivesynthesis of 1-aryl-3,4,5-substituted pyrazoles based on the condensation of 1,3-diketones with arylhydrazines is described. The reaction proceeds at room temperature in N,N-dimethylacetamide and furnishes pyrazoles in 59-98% yields.
The reaction of aryl and heteroarylhydrazines with aryl-trifluoromethyl β-diketones
作者:Shiv P. Singh、Vinod Kumar、Ranjana Aggarwal、Jose Elguero
DOI:10.1002/jhet.5570430428
日期:2006.7
We report the results obtained when five aromatic or heteroaromatic hydrazines react with six β-diketones bearing trifluoromethyl and aryl substituents. Forty-two compounds have been isolated corresponding to two isomeric trifluoromethyl pyrazoles and the intermediate 5-CF3, 5-OH pyrazolines. The results have provided useful information for establishing the mechanism of the synthesis of pyrazoles.
Mild and Regioselective Synthesis of 3-CF<sub>3</sub>
-Pyrazoles by the AgOTf-Catalysed Reaction of CF<sub>3</sub>
-Ynones with Hydrazines
作者:Maxim A. Topchiy、Daria A. Zharkova、Andrey F. Asachenko、Vasiliy M. Muzalevskiy、Vyacheslav A. Chertkov、Valentine G. Nenajdenko、Mikhail S. Nechaev
DOI:10.1002/ejoc.201800208
日期:2018.8.1
heterocyclization reactions to selectively give 3‐CF3‐pyrazoles. AgOTf was found to be the catalyst of choice, and various 3‐CF3‐pyrazoles were formed in up to 99 % isolated yield with high regioselectivity. The reaction has a broad scope: 3‐CF3‐pyrazoles with alkyl and aryl substituents as well as different functional groups can be prepared by this approach. The known pyrazole drugs Celebrex® and SC‐560 were efficiently
Metallaphotoredox‐Catalyzed Enantioselective Cross‐Electrophile Coupling Using Alcohols as Reducing Agents
作者:Zhilong Li、Leitao Huan、Jian Li、Xiaomin Shu、De Zhong、Wenjing Zhang、Haohua Huo
DOI:10.1002/anie.202305889
日期:2023.8
An enantioselective coupling of α-amino acid derivatives and aryl bromides, using Ni/photoredox catalysis and alcohols as reducingagents, is reported. This protocol offers modular access to enantioenriched benzylic amines from abundant precursors, and is suitable for late-stage diversification with broad functional group tolerance. The alcohol-based approach holds potential as a general platform for
Synergic Effects of Ionic Liquid and Microwave Irradiation in Promoting Trifluoromethylpyrazole Synthesis
作者:Lilian Buriol、Clarissa P. Frizzo、Liziê D. T. Prola、Dayse N. Moreira、Mara R. B. Marzari、Elisandra Scapin、Nilo Zanatta、Helio G. Bonacorso、Marcos A. P. Martins
DOI:10.1007/s10562-011-0571-9
日期:2011.8
The synthesis of 5-trifluoromethyl-1-phenyl-1H-pyrazoles from the reactions of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones [CF3C(O)CH=C(R-1)OR, where R = Me, Et; R-1 = H, Me, Bu, i-Bu, Ph, 4-MeC6H4, 4-FC6H4, 4-ClC6H4, 4-BrC6H4, 4-IC6H4, fur-2-yl] with phenyl hydrazine in the presence of ionic liquid [BMIM][BF4] is reported. Synergic effects of ionic liquid and microwave irradiation in promoting pyrazole synthesis have been shown for the first time.