- Oxone-DMSO Triggered Methylene Insertion and C(sp2)-C(sp3)-H-C(sp2) Bond Formation to Access Functional Bis-Heterocycles
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Metal-free insertion of a methylene group was achieved for the construction of a new C(sp2)-C(sp3)-H-C(sp2) bond in order to prepare novel bis-heterocyclic scaffolds. The complete mechanistic investigations included experimental study and DFT calculations, and various symmetric and unsymmetric bis-pyrazoles as well as other pyrazole-based bis-heterocyclic molecules were prepared in moderate to high yields. Further modification of the bridged methylene group in the unsymmetric pyrazoles generated a chiral center to extend the scope of this method.
- Bharatam, Prasad V.,Dubey, Gurudutt,Hussain, Yaseen,Kour, Jaspreet,Sahoo, Subash C.,Sawant, Sanghapal D.,Venkateswarlu, Vunnam,Verma, Praveen K.
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supporting information
p. 4951 - 4962
(2020/05/08)
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- Copper-Mediated Domino Cyclization/Trifluoromethylation/Deprotection with TMSCF3: Synthesis of 4-(Trifluoromethyl)pyrazoles
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A copper-mediated synthesis of 4-(trifluoromethyl)pyrazoles is described. In one step from readily accessible α,β-alkynic tosylhydrazones, a remarkable domino sequence of cyclization, trifluoromethylation, and detosylation takes place to furnish the 4-CF3 N-H pyrazole cores with good functional group compatibility. The reaction conditions are mild and convenient, at room temperature in air, using the commercially available trifluoromethyltrimethylsilane (TMSCF3) as the CF3 source. The method can be applied to the synthesis of a 4-CF3 analogue of the anti-inflammatory drug celecoxib.
- Wang, Quande,He, Lisi,Li, Kin Keung,Tsui, Gavin Chit
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supporting information
p. 658 - 661
(2017/02/10)
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- Cycloisomerization of acetylenic oximes and hydrazones under gold catalysis: Synthesis and cytotoxic evaluation of isoxazoles and pyrazoles
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The synthesis of substituted isoxazoles and pyrazoles through a general cycloisomerization methodology has been reported. The capability of gold(III) chloride to promote cycloisomerization of both α, β-acetylenic oximes and α, β-acetylenic hydrazones is t
- Jeyaveeran,Praveen, Chandrasekar,Arun,M Prince,Perumal
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- Copper-catalyzed synthesis of alkynyl hydrazones from alkynes and hydrazonyl chlorides
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A novel ligand-free synthesis of alkynyl hydrazones via coupling reaction of hydrazonyl chlorides and terminal alkynes, catalyzed by CuI led to excellent yields. Copyright
- Yavari, Issa,Nematpour, Manijeh,Yavari, Sima,Sadeghizadeh, Fatemeh
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p. 1136 - 1139
(2014/09/29)
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- Synthesis of pyrazoles via electrophilic cyclization
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Electrophilic cyclizations of α,β-alkynic hydrazones by molecular iodine were investigated for the synthesis of 4-iodopyrazoles. α,β-Alkynic hydrazones were readily prepared by the reactions of hydrazines with propargyl aldehydes and ketones. When treated with molecular iodine in the presence of sodium bicarbonate, α,β-alkynic hydrazones underwent electrophilic cyclization to afford 4-iodopyrazoles in good to high yields. Iodocyclization was general for a wide range of α,β-alkynic hydrazones and tolerated the presence of aliphatic, aromatic, heteroaromatic, and ferrocenyl moieties with electron-withdrawing and electron-donating substituents.
- Zora, Metin,Kivrak, Arif,Yazici, Ceyda
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experimental part
p. 6726 - 6742
(2011/10/09)
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