33064-21-0Relevant articles and documents
Primary Vinyl Ethers as Acetylene Surrogate: A Flexible Tool for Deuterium-Labeled Pyrazole Synthesis
Ananikov, Valentine P.,Lebedev, Andrey N.,Ledovskaya, Maria S.,Polynski, Mikhail V.,Voronin, Vladimir V.
, (2020/07/24)
A novel synthetic path to 1,3-disubstituted pyrazoles and their deuterated derivatives was developed. It is based on the reaction of vinyl ethers with hydrazonoyl chlorides in the presence of triethylamine. The reaction mechanism, clarified by the joint experimental and computational study, involves 1,3-dipolar cycloaddition of the in situ generated nitrile imines to vinyl ethers and subsequent cleavage of alcohol from the formed alkoxypyrazoline. The results highlight the possibility of using vinyl ethers as acetylene surrogate and provide a novel access to pyrazoles, 4,5-dideuteropyrazoles and their regioselectively labeled derivatives, 5-deuteropyrazoles.
Molybdenum-Mediated One-Pot Synthesis of Pyrazoles from Isoxazoles
Beaumont, Stéphane,Rey, Marine
, p. 3796 - 3804 (2019/10/11)
A one-pot approach for the direct synthesis of substituted pyrazoles from isoxazoles is reported. The process involves isoxazole N-O bond cleavage mediated by a molybdenum complex, in situ hydrolysis of the resulting β-amino enone to the corresponding 1,3-diketone, followed by pyrazole formation in the presence of hydrazine or substituted hydrazine. Good to excellent yields and regioselectivities are obtained with nonsymmetric isoxazoles. By using readily available starting materials, a wide range of substituted pyrazoles may be synthesized by this method.
Facile synthesis of pyrazoles by iron-catalyzed regioselective cyclization of hydrazone and 1,2-diol under ligand-free conditions
Panda, Niranjan,Ojha, Subhadra
, p. 244 - 251 (2018/03/13)
A facile synthesis of pyrazoles by the cyclization of hydrazones and 1,2-diols was described. In the presence of ferric nitrate, the reaction occurs under neat conditions and makes the use of potassium persulfate to oxidize the diol to α-hydroxy carbaldehyde for the reaction with hydrazones to produce 1,3- and 1,3,5-substituted pyrazoles selectively. The overall regioselective transformation occurs in one-pot under ligand-free, mild conditions even in the presence of air.