Novel 4,5-bis(trifluoromethyl)-1H-pyrazoles through a concise sequential iodination-trifluoromethylation reaction
摘要:
An efficient protocol for the assembly of a new series of 1,3-disubstituted 4,5-bis(trifluoromethyl)-1H-pyrazoles - through a concise sequential iodination-trifluoromethylation reaction at the C-4 position of an initial series of 1-aryl-3-(alkyl/aryl)-5-trifluoromethyl-1H-pyrazoles (electronically deactivated heterocycles), using NIS and MFSDA, at good conversion yields and in short reaction times - is reported. (C) 2019 Elsevier Ltd. All rights reserved.
A General and Regioselective Synthesis of 5-Trifluoromethyl-pyrazoles
作者:Robert S. Foster、Harald Jakobi、Joseph P. A. Harrity
DOI:10.1021/ol3021918
日期:2012.9.21
Two synthetic approaches to 4-trifluoromethylsydnones, a novel class of these mesoionic reagents, are reported. These compounds undergo regioselective alkyne cycloaddition reactions, thereby providing a generalapproach to 5-trifluoromethylpyrazoles. This method has been employed in a short formal synthesis of the herbicide fluazolate.
Solvent- and Transition Metal Catalyst-Dependent Regioselectivity in the [3+2] Cyclocondensation of Trifluoromethyl<i>-</i>α,β<i>-</i>ynones with Hydrazines: Switchable Access to 3- and 5-Trifluoromethylpyrazoles
作者:Min-Tsang Hsieh、Sheng-Chu Kuo、Hui-Chang Lin
DOI:10.1002/adsc.201400853
日期:2015.3.9
The regioselectivity of the [3+2] cyclocondensation of trifluoromethyl‐α,β‐ynones with hydrazines can be readily tuned to preferentially afford either 3‐ or 5‐trifluoromethylpyrazoles through variation of the reaction conditions. Under catalysis with copper(II) acetate (2.0 mol%), cyclocondensation proceeded smoothly to yield 3‐trifluoromethylpyrazoles with high regioselectivity. In contrast, when
Microwave assisted regiospecific synthesis of 5-trifluoromethyl-4,5-dihydropyrazoles and-pyrazoles
作者:Marcos A. P. Martins、Claudio M. P. Pereira、Sidnei Moura、Clarissa P. Frizzo、Paulo Beck、Nilo Zanatta、Helio G. Bonacorso、Alex F. C. Flores
DOI:10.1002/jhet.5570440537
日期:2007.9
The regiospecificsynthesis of a series of twelve 5-trifluoromethyl-4,5-dihydropyrazoles and -pyrazoles from the cyclocondesation reaction of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones [F3CC(O)CH=C(R1)OR, where R1 = Me, Et, Pr, iso-Pr, Bu, iso-Bu, Ph, H; and R = Me, Et] with phenylhydrazine in toluene by environmentally benign microwave induced techniques is reported. It is shown that under appropriated
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.