73225-12-4

Upstream product

• 34292-79-0 4-phenyl-but-3-en-2-one-(4-nitro-phenylhydrazone) 
• 34326-52-8 3-methyl-1-(4-nitro-phenyl)-5-phenyl-4,5-dihydro-1H-pyrazole 
• 52943-87-0 5-bromo-3-methyl-1-(4-nitro-phenyl)-1H-pyrazole 
• 98-80-6 phenylboronic acid 
• 343866-81-9 3-benzoyl-4-(t-butylamino)-3-penten-2-one 
• 100-16-3 4-nitrophenylhydrazone 
• 98-88-4 benzoyl chloride 
• 1318239-58-5 C₁₆H₁₃N₃O₂ 
• 6402-09-1 1-(4'-nitrophenyl)-3-methyl-5-pyrazolone 
• 108086-92-6 3-benzoyl-4-(methylamino)-3-penten-2-one 
• 23652-90-6 (2Z)-3-amino-1-phenylbut-2-en-1-one 
• 93-91-4 1-phenylbutan-1,3-dione 

Downstream Products

• 133132-05-5 4-bromo-3-methyl-1-(4-nitro-phenyl)-5-phenyl-1H-pyrazole 

Relevant academic research and scientific papers

An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes

α-Halohydrazones/ketoximes are transformed into trisubstituted pyrazoles/disubstituted isoxazoles by treatment with phosphine, acyl chloride, and a base. Mechanistic investigations revealed the in situ formation of azo/nitroso olefin intermediates which underwent a tandem phospha-Michael/N- or O-acylation/intramolecular Wittig reaction to afford the heteroarenes in moderate to good yields. Further, proper functionalization of α-haloketoximes and a change of conditions allowed the chemoselective synthesis of chromenone-oximes as well as rearranged isoxazoles, thereby realizing a diversity-oriented synthesis.

A novel synthesis of fluorinated pyrazoles via gold(I)-catalyzed tandem aminofluorination of alkynes in the presence of Selectfluor

A mild and efficient protocol for the synthesis of fluorinated pyrazoles has been developed via gold(I)-catalyzed tandem aminofluorination of alkynes in the presence of Selectfluor. This method offers a broad substrate scope.

5-Hydroxy-2-pyrazolines and some of their 1-substituted analogs

The use of 1,3-dicarbonyl compounds containing strong electron-withdrawing substituents (perfluoroalkyl, 4-nitrophenyl) at one of the carbonyl groups in reaction with hydrazine or its monosubstituted derivatives (4-nitro- and 2,4-dinitrophenylhydrazines) leads to the formation of stable intermediates for the synthesis of pyrazoles (5-hydroxy-2-pyrazolines) or their linear tautomers (hydrazones).

Study of the reactivity of α-acylenaminoketones. Synthesis of pyrazoles

The reactions of 4-(methylamino)-3-penten-2-one with diazoketones yielded the α-acylenaminoketones 1-3 in good yields. Preparation of the α-acylenaminoketone 4 was carried out by treatment of 4-(t-butylamino)-3-penten-2-one with benzoyl chloride being followed by reaction of transamination with methylamine. The reactions were carried out in five different solvents and were submitted to gas chromatography/mass spectrometry analysis, with the goal of obtaining substituted pyrazoles and determining which of the carbonyls would preferentially be attacked by the nucleophile. The reactions of compounds 1-4 with hydrazine reagents led to the formation of the pyrazoles 5-7a-q. Small amounts of 4-methylamino-2-pentenones 10a-q, amides 11a-q and pyrazoles 12a-q were also obtained in these reactions. The unexpected formation of pyrazoles 15d,h,q was detected when methanol and N,N-dimethylformamide were used as solvents in the reactions of α-acylenaminoketone 4 with hydrazine reagents.

Scope and limitations in the regioselective synthesis of 1,3,5-trisubstituted pyrazoles from β-amino enones and hydrazine derivatives. 13C-chemical shift prediction rules for 1,3,5-trisubstituted pyrazoles

β-amino enones react with hydrazine derivatives to give regioselectively 1,3,5-trisubstituted pyrazoles. The synthetic method only presents limitations when the β-substituent of the enone and the hydrazine substituent are bulky or possess an electron withdrawing character. Comparison of the 13C-NMR spectra of the seventy pyrazoles allowed us to estimate a 13C-chemical shift prediction rule for 1,3,5-trisubstituted pyrazoles, with deviations of less than ± 1 ppm.

Cross-coupling of 1-aryl-5-bromopyrazoles: Regioselective synthesis of 3,5-disubstituted 1-arylpyrazoles

The cross-coupling of 1-aryl-5-bromopyrazoles 4 with alkynes, vinyltins and arylboronic acids promoted by Pd(PPh3)4 afforded unsymmetrical 3,5- disubstituted 1-arylpyrazoles 5-8 in excellent yields, 1-Aryl-5- bromopyrazoles 4 were prepared from their corresponding 1-arylpyrazolones 3 with PBr3 in refluxing acetonitrile. (C) 2000 Elsevier Science Ltd.

5-Hydroxy-4,5-Dihydropyrazoles

The use of β-diketones with strong electron-withdrawing substituents in reaction with hydrazine and its monosubstituted derivatives leads to the stable intermediates of pyrazole synthesis - 5-hydroxy-4,5-dihydropyrazoles or their open chain isomers.

Oxidative Cyclization of Arylhydrazones of Chalcones and Benzalacetones to Pyrazoles by Thianthrene Cation Radical

Phenyl-, (p-nitrophenyl)-, and (2,4-dinitrophenyl)hydrazones of chalcone (benzalacetophenone), benzalacetone, and of some of their derivatives undergo oxidative cyclization in reactions with thianthrene cation radical perchlorate.The products are, respect