27293-99-8

Upstream product

• 100-06-1 1-(4-methoxyphenyl)ethanone 
• 2168-78-7 methyl dithiobenzoate 
• 76526-09-5 (Z)-3-hydroxy-3-(4-methoxyphenyl)-1-phenylprop-2-ene-1-thione 
• 1073-69-4 N-4-chlorophenylhydrazine 
• 60798-13-2 2-phenyl-5-(4'-chloro-phenyl)-2,4-dihydro-3H-pyrazol-3-one 
• 94-02-0 ethyl 3-oxo-3-phenylpropionate 
• 5720-07-0 4-methoxyphenylboronic acid 
• 293315-44-3 5-bromo-1-(4-chlorophenyl)-3-phenyl-1H-pyrazole 

Relevant academic research and scientific papers

Cyclocondensation of arylhydrazines with 1,3-bis(het)arylmonothio-1,3- diketones and 1,3-Bis(het)aryl-3-(methylthio)-2-propenones: Synthesis of 1-Aryl-3,5-bis(het)arylpyrazoles with complementary regioselectivity

Two efficient highly regioselective routes for the synthesis of unsymmetrically substituted 1-aryl-3,5-bis(het)arylpyrazoles with complementary regioselectivity starting from active methylene ketones have been reported. In the first protocol, the newly synthesized 1,3-bis(het)aryl-monothio-1,3-diketone precursors (prepared by condensation of active methylene ketones with het(aryl) dithioesters in the presence of sodium hydride) were reacted with arylhydrazines in refluxing ethanol under neutral conditions, furnishing 1-aryl-3,5-bis(het)arylpyrazoles 7, in which the het(aryl) moiety attached to the thiocarbonyl group of monothio-1,3-diketones is installed at the 3-position. In the second method, the corresponding 3-(methylthio)-1,3-bis(het)aryl-2- propenones (prepared in situ by base-induced alkylation of 1,3- monothiodiketones) were condensed with arylhydrazines in the presence of potassium tert-butoxide in refluxing tert-butyl alcohol, yielding 1-aryl-3,5-bis(het)arylpyrazoles 9 with complementary regioselectivity (method A). The efficiency of this protocol was further improved by developing a one-pot, three-component procedure for the synthesis of pyrazoles 9, directly from active methylene ketones, by reacting in situ generated 3-(methylthio)-1,3-bis(het)aryl-2-propenones with arylhydrazines in the presence of sodium hydride (instead of potassium tert-butoxide as base). The structures and regiochemistry of newly synthesized pyrazoles were confirmed from their spectral and analytical data along with X-ray crystallographic data of three pairs of regioisomers.

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.