- A highly efficient heterogeneous palladium-catalyzed cascade three-component reaction of acid chlorides, terminal alkynes and hydrazines leading to pyrazoles
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In the presence of 0.5 mol% of 3-(2-aminoethylamino)propyl-functionalized MCM-41-immobilized palladium(II) complex [MCM-41-2N-Pd(OAc)2] and 1.0 mol% of CuI, acid chlorides were coupled with terminal alkynes in Et3N at 50 °C to give α,β-unsaturated ynones, which were converted in situ into pyrazoles by the cycloaddition of hydrazines at room temperature with acetonitrile as cosolvent. The cascade reactions generated a variety of pyrazole derivatives in moderate to good yields, and this heterogeneous palladium catalyst exhibited higher catalytic activity than PdCl2(PPh3)2 and could be recovered and reused for at least 10 consecutive trials without any decreases in activity.
- Chen, Qiurong,Yao, Fang,Yin, Lin,Cai, Mingzhong
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p. 108 - 113
(2016/01/15)
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- Solvent-free synthesis of 3,5-di-tert-butylpyrazole and 3,5-di-substitutedbutylpyrazol-1-ylethanol
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A high-yield, solvent-free approach to the synthesis of 1,3,5-trisubstituted pyrazoles is reported. Four compounds, (3,5-di-tert-butyl- 1H-pyrazole, (2-(3,5-dimethyl-1H-pyrazol-1-yl)ethanol, 2-(3,5-di-tert-butyl-1H- pyrazol-1-yl)ethanol, 2-(3,5-diphenyl-1
- Van Wyk, Juanita L.,Omondi, Bernard,Appavoo, Divambal,Guzei, Ilia A.,Darkwa, James
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p. 474 - 477
(2012/10/29)
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- Study of the coordination behaviour of (3,5-diphenyl-1H-pyrazol-1-yl) ethanol against Pd(II), Zn(II) and Cu(II)
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A new easily synthetic route with a 96% yield of ligand 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethanol (L) is obtained. The reactivity of L against Pd(II), Zn(II) and Cu(II) leads to [PdCl2(L)2] (1), [ZnCl2(L)] (2) and [CuCl(L′)]
- Mu?oz, Sergio,Pons, Josefina,Ros, Josep,Font-Bardia, Mercè,Kilner, Colin A.,Halcrow, Malcolm A.
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experimental part
p. 211 - 218
(2011/08/22)
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- One-pot three-component synthesis of pyrazoles through a tandem coupling-cyclocondensation sequence
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An efficient and general one-pot procedure for the synthesis of pyrazoles from acid chlorides, terminal alkynes and hydrazines was described via a coupling and cyclocondensation sequence. Acid chlorides coupled with terminal alkynes to give α,β-unsaturated ynones, and in situ converted into pyrazoles by the cycloaddition of hydrazines. The desired pyrazoles were obtained with 15-85% isolated yields.
- Liu, Hai-Ling,Jiang, Huan-Feng,Zhang, Min,Yao, Wen-Juan,Zhu, Qiu-Hua,Tang, Zhou
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p. 3805 - 3809
(2008/09/21)
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