20157-46-4

Upstream product

• 67-51-6 3,5-dimethyl-1H-pyrazole 
• 106-43-4 para-chlorotoluene 
• 352-32-9 p-fluorotoluene 
• 637-60-5 p-tolylhydrazine hydrochloride 
• 123-54-6 acetylacetone 
• 10199-63-0 1-(3,5-dimethyl-1H-pyrazol-1-yl)ethanone 
• 5720-05-8 4-methylphenylboronic acid 
• 539-44-6 N-4-methylphenylhydrazine 

Downstream Products

• 108444-21-9 3,5-Dimethyl-1-p-tolyl-1H-pyrazole-4-carboxylic acid 
• 91768-96-6 3,5-dimethyl-4-thiocyanato-1-(p-tolyl)-1H-pyrazole 

Relevant academic research and scientific papers

Preparation method of pyrazole derivative

The present invention discloses a method for preparing a pyrazole derivative. The method comprises the following steps: the arylhydrazine derivative is mixed with an alkyldione derivative, reaction, to obtain a pyrazole derivative; wherein the structure of the arylhydrazine derivative is as follows: the structure of the alkyldione derivative is as follows: the structure of the pyrazole derivative provided by the present invention is green safe, simple and efficient, mild conditions, no catalyst, low cost, high synthesis efficiency. This method can synthesize a variety of 1,3,4,5-tetra-substituted pyrazole derivatives, and the method can be widely used in the field of organic synthesis.

Cross-Coupling between Hydrazine and Aryl Halides with Hydroxide Base at Low Loadings of Palladium by Rate-Determining Deprotonation of Bound Hydrazine

Reported here is the Pd-catalyzed C–N coupling of hydrazine with (hetero)aryl chlorides and bromides to form aryl hydrazines with catalyst loadings as low as 100 ppm of Pd and KOH as base. Mechanistic studies revealed two catalyst resting states: an arylpalladium(II) hydroxide and arylpalladium(II) chloride. These compounds are present in two interconnected catalytic cycles and react with hydrazine and base or hydrazine alone to give the product. The selectivity of the hydroxide complex with hydrazine to form aryl over diaryl hydrazine was lower than that of the chloride complex, as well as the catalytic reaction. In contrast, the selectivity of the chloride complex closely matched that of the catalytic reaction, indicating that the aryl hydrazine is derived from this complex. Kinetic studies showed that the coupling process occurs by rate-limiting deprotonation of a hydrazine-bound arylpalladium(II) chloride complex to give an arylpalladium(II) hydrazido complex.

Visible-light enabled C4-thiocyanation of pyrazoles by graphite-phase carbon nitride (g-C3N4)

Thiocyanation is an important and effective way to form C[sbnd]S bonds in organic synthetic methodology. Especially, thiocyanation of pyrazole attracts the attention of many researchers because sulfur-containing compounds are widely applied in many crucial fields such as organic materials, agrochemistry, nanotechnology, etc. Herein, we described A rapid metal- and additive-free method for C(sp2)-H thiocyanation of pyrazoles under visible light at room temperature by using a sustainable catalyst of graphite-phase carbon nitride (g-C3N4) and a thiocyanating agent of ammonium thiocyanate. The method presents many advantages, such as usage of eco-friendly photoredox catalyst, a wide range of substrates and a good yield of products, etc.

Nucleophilic aromatic substitution of unactivated fluoroarenes enabled by organic photoredox catalysis

Nucleophilic aromatic substitution (SNAr) is a classical reaction with well-known reactivity toward electron-poor fluoroarenes. However, electron-neutral and electron-rich fluoro(hetero)arenes are considerably underrepresented. Herein, we present a method for the nucleophilic defluorination of unactivated fluoroarenes enabled by cation radical-accelerated nucleophilic aromatic substitution. The use of organic photoredox catalysis renders this method operationally simple under mild conditions and is amenable to various nucleophile classes, including azoles, amines, and carboxylic acids. Select fluorinated heterocycles can be functionalized using this method. In addition, the late-stage functionalization of pharmaceuticals is also presented. Computational studies demonstrate that the site selectivity of the reaction is dictated by arene electronics.

Oxone-DMSO Triggered Methylene Insertion and C(sp2)-C(sp3)-H-C(sp2) Bond Formation to Access Functional Bis-Heterocycles

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.

PROCESS FOR THE SYNTHESIS OF ARYL HYDRAZINES

The invention relates to a process for the synthesis of aryl hydrazinesof formula I or a salt thereof, which process comprises subjecting an arene of formula II to a coupling reaction with hydrazine or a derivative thereof, wherein the coupling reaction is conducted in the presence of a catalyst comprising palladium and a diphosphine ligand, wherein the phosphorus atoms are connected through two, three, four, or five atoms selected from car- bon, nitrogen, oxygen or iron, and in which the non-connecting phosphorus substituents are C1- C 10-alkyl or C3-C10-cycloalkyl, wherein the amount of Pd used is up to 0.5 mol-% relative to the amount of arene of formula II; and a base.

1-Aryl-3,5-dimethylpyrazolium based tunable protic ionic liquids (TPILs)

A series of new 1-aryl-3,5-dimethylpyrazolium based tunable protic ionic liquids/salts ([PhRHpz][X], R: –H, –Cl, –Br, –CH3, –OCH3, X: chloride [Cl?] and tetrafluoroborate [BF4 ?]) have been synthesized through acid-base neutralization reactions between 1-aryl-3,5-dimethyl-1H-pyrazoles and the corresponding inorganic acids. The chemical structure of the salts was confirmed by FTIR, 1H NMR, 13C NMR, elemental analysis, and 19F NMR (3a-3e) and the crystal structure of the two salts (2a and 3d) was also elucidated by X-ray analysis of single crystals. Melting points and thermal decomposition temperatures of TPILs (2e and 3b) were determined. The geometries of the cations, anions and ionic salts were optimized, and their molecular electrostatic potentials (MEPs) were assessed by using density functional theory methods (B3LYP and M06-2X). The electrochemical window of the salts was determined both experimentally and theoretically. The correlation coefficient values were also calculated by using theoretical and experimental EW values of the salts.

Direct N-heterocyclization of hydrazines to access styrylated pyrazoles: synthesis of 1,3,5-trisubstituted pyrazoles and dihydropyrazoles

A microwave-assisted method has been developed for the synthesis of tri-substituted pyrazoles via direct N-heterocyclization of hydrazines with metal-acetylacetonate and -dibenzylideneacetonate without using any base or additives. Most importantly, the synthesis of 1-aryl-5-phenyl-3-styryl-1H-pyrazoles was achieved in a single step using hydrochloride salt of various phenylhydrazines and this is the first report for direct construction of these molecules. The reaction medium and microwave conditions play a critical role for their selective product formation during the reaction. The present reaction explored the usage of metal-diketonic complexes as reaction substrates providing acetylacetone and dibenzylideneacetone moieties to directly participate in cyclization with hydrazines to form the corresponding pyrazoles in excellent yields. The present protocol introduces the important N-heterocyclic moieties in the final structures, giving the reaction great applications from a medicinal chemistry perspective, particularly in the late stage modification strategies in drug discovery.

Synthesis of Unsymmetrical 2,6-Diarylanilines by Palladium-Catalyzed C-H Bond Functionalization Methodology

3,5-Dimethylpyrazole was employed as a monodentate directing group for palladium-catalyzed ortho-sp2 C-H arylation with aryl iodides. The reaction shows good functional group tolerance and outstanding selectivity for mono-ortho-arylation. Ozonolysis of ortho-arylated arylpyrazoles gave acylated biphenylamines that were further arylated to afford unsymmetrically substituted 2,6-diarylacetanilides.

Application and developing of iron-doped multi-walled carbon nanotubes (Fe/MWCNTs) as an efficient and reusable heterogeneous nanocatalyst in the synthesis of heterocyclic compounds

Iron-doped multi-walled carbon nanotubes (Fe/MWCNTs) is an efficient, ecofriendly and reusable heterogeneous nanocatalyst for the one-pot synthesis of heterocyclic compounds including bis-spiro piperidines, piperidines, dihydro-2-oxopyrroles, pyrazoles and diazepines at room temperature with good to excellent yields. The heterogeneous nanocatalyst was fully characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma (ICP) and FT-IR analysis. Also, the structures of all prepared compounds were characterized by 1H NMR, 13C NMR, FT-IR, mass spectrometry (MS) and elemental analysis. The major advantages of these protocols are mild and green reaction conditions, short reaction times, clean reaction, operational simplicity, easy purification and good to excellent yields with the reusable heterogeneous nanocatalyst. The catalyst was ten recycled without significant loss of activity.