3.5- diphenyl-4-pyrazole

Cyano-7-[cyano-(3-methylenc-cyclobutylidene)-methyl]- 531 IH-Pyrazole 3,5-Diphenyl- 2141 3H-Pyrazole... 

German or Japanese authors name these dyes (3-ethyl-4,5-diphenylthiazole-2)(3-ethylrhodanine-5)-0-methine neutrocyanine and (3-methyl-4,5-diphenyl thiazole-2)(3-methyl-l-p-sulfophenyl-2-pyrazol-5-one-4)tetramethineneutrocyanine, respectively. 

Amination at an azole ring nitrogen is known for Af-unsubstituted azoles. Thus 4,5-diphenyl-1,2,3-triazole with hydroxylamine-O-sulfonic acid gives approximately equal amounts of the 1- (104) and 2-amino derivatives (105) (74AHC(16)33). Pyrazole affords (106) and indazole gives comparable amounts of the 1- and 2-amino derivatives. 

A Hammett relationship of the form ApK = 5.8am has been proposed for 4-substituted pyrazoles (74TL1609) in order to explain the effect of 4-nitro ApK = 4.5, am = 0.71) and 4-diazo groups (Apiifa = 10.0, am = 1.76). The acidity constants of a series of pyrazolidine-3,5-diones have been determined (75AJC1583) and the 4- -butyl-1,2-diphenyl derivative phenylbutazone has a pK of 4.33. 

Pyrazole, 1 -(2,4-dinitrophenyl)-3-methyl-bromination, S, 240 Pyrazole, 2,3-diphenyl-synthesis... 

The use of diphenyl hydrazone 33 has been used in the synthesis of pyrazoles under modified conditions where the hydrazine is released in situ. Some reversal of regiochemistry is seen in the reaction with unsymmetrical dicarbonyls. With aryl hydrazine and diphenyl hydrazone, the ratio of 41 to 42 is 22 1 and 5 1, respectively. 

Examples of dynamic processes involving two, three, or four identical tautomers (degenerate or autotrope annular tautomerism) have been found in pyrazoles (type 2 of Table VII). Thus, 3,5-diphenyl-4-bromopyr-azole and 3,5-di-ferf-butylpyrazole (dimers), 3,5-dimethyl-pyrazole (trimer). 

Abbreviations acac, acetylacetonate Aik, alkyl AN, acetonitrile bpy, 2,2 -bipyridine Bu, butyl cod, 1,5- or 1,4-cyclooctadiene coe, cyclooctene cot, cyclooctatetraene Cp, cyclopentadienyl Cp, pentamethylcyclopenladienyl Cy, cyclohexyl dme, 1,2-dimethoxyethane dpe, bis(diphenyl-phosphino)ethane dppen, cis-l,2-bis(di[Atenylphosphino)ethylene dppm, bis(diphenylphosphino) methane dppp, l,3-bis(diphenylphosphino)propane eda,ethylenediamine Et,ethyl Hal,halide Hpz, pyrazole HPz, variously substituted pyrazoles Hpz, 3,5-dimethylpyrazole Me, methyl Mes, mesityl nbd, notboma-2,5-diene OBor, (lS)-endo-(-)-bomoxy Ph, phenyl phen, LlO-phenanthroline Pr, f opyl py, pyridine pz, pyrazolate Pz, variously substituted pyrazolates pz, 3,5-dimethylpyrazolate solv, solvent tfb, tetrafluorobenzo(5,6]bicyclo(2.2.2]octa-2,5,7-triene (tetrafluorobenzobanelene) THE, tetrahydrofuran tht, tetrahydrothicphene Tol, tolyl. 

Sodium pyrazolate and 3,5-dimethylpyrazolate, [( " -cod)Rh(/A-Cl)]2, carbon monoxide, 3-(diphenylphosphino)benzoic acid, or (2-formylphenyl)diphenyl-phosphine give rise to complexes 120 (R = H, Me) and 121 (R = H, Me) [94JOM(469)213]. However, 2-(diphenylphosphino)benzoic acid (the carboxyl group in the ortho position) leads to formation of the mononuclear complexes 122. The products appear to be catalysts for hydroformylation reactions [93MI2]. 

The authors reported the synthesis of 5-but-l-ynyl-l- phenyl-l//-pyrazole-3-car-boxylic acid ethyl ester and 5-but-1 -ynyl-1,3-diphenyl- l//-pyrazole, but they were not able to purify the compounds (Scheme 17). 

The reaction direction remains the same for methyldiacetylene and diphenyl-diacetylene (120°C, 20 h, yield 85.8%) (71AKZ743), the cyclization products being 1,3,5-trisubstituted pyrazoles 20 and 21. 

Dipolar cycloaddition of 2-diazopropane and 1,3-diphenyldinitrilimine to E- and Z-methoxybutenynes occurs at the triple bond to form 3,3-dimethyl-5-(2-methoxyvinyl)pyrazole (168) and a mixture of , Z-l,3-diphenyl-4- (169) and -5-(2-methoxyvinyl)pyrazole (170) [70CR(C)80]. 

Recently, the pyrazole group containing bisphenols have been synthesized from activated aromatic dihalides and 3,5-bis (4-hydroxy phenyl)-4-phenyl pyrazole or 3,5-bis(4-hydroxy phenyl)-1,4-diphenyl pyrazole. A novel synthesis of imido aryl containing bisphenols has been reported [32]. N-substituted l,4-bis(4-hydroxy phenyl)-2,3-naphthalimides were prepared from phenolphthalein and copolymerized with aromatic sulfone or ketone difluorides to obtain the poly(imidoaryl ether) sulfones/ ketones. 

However, when 3,5-diphenyl-4//-pyrazol-4-one, a reagent that undergoes Diels- Alder reactions with inverse-electron demand, is used, addition of the 2,4-diene part of oxepin to one of the two C-N double bonds of the pyrazolone is observed to give 4.232... 

In contrast, the structurally similar and equally powerful diene, 3,5-diphenyl-4//-pyrazol-4-one (24), generated in situ by the thermolysis of l,3-bis(diazo)-l,3-diphenylacetone, affords only a modest yield of the [4 + 2] e ifo,ant/-cycloadduct 25.262... 

Thermolysis of 4-benzyl-3,7-diphenyl-4/7-l,2,4-triazepine gives a mixture of the rearranged pyrazole 2, 2.4-diphenylpyrimidine and l-benzyl-4-phenylimidazole.341... 

Vinylcarbenes. The use of diazoalkenes as vinylcarbene precursors is often precluded by rapid cyclization, with formation of pyrazoles. However, on photochemical generation of the diazoalkenes in situ, cyclization and nitrogen extrusion can proceed competitively. Photolysis of 1,3-diphenylpropenone to-sylhydrazone sodium salt (5) in MeOD afforded 3,5-diphenylpyrazole (9) and l,3-diphenyl-3-methoxypropene (10) in similar amounts.17 If 10 is formed by way of the 1,3-diphenylallyl cation (8), the deuterium should be distributed between C-l and C-3 of 10 (Scheme 6). The observed ratio of 10a to 10b was 66 34 the methoxy group is bound preferentially to the deuterated site, which originates from the divalent carbon of 7 (for a discussion of this effect, see below). 

The proton dissociation constants, of two series of 3,7-bis(arylazo)-2,6-diphenyl-1 //-irnidazo[l,2-7]pyrazoles, in the ground state and the excited state were determined by the spectrophotometric method and utilizing the Forster energy cycle, respectively. These constants were correlated by the Hammett equation and the results of such correlations with spectral data indicated that both series of compounds exist in solution almost exclusively in the l//-bis-(arylazo) tautomeric form A <2002T2875> (Scheme 3). 

With a-hydroxy ketones and their related tosyloxy derivatives. The imidazo [2,T ]thiazole 364 was prepared by acetic acid-catalyzed cyclocondensation of 2-hydroxy-l,2-diphenyl-ethanone with thiophenyl-substituted 2-aminothiazole 363 (Equation 163) <2002MI110>. Under MW irradiation and in the presence of montmorillonite K-10 clay, a mixture of a-tosyloxyketones 365 and 2-imidazolidinethione led to the substituted 5,6-dihydro-imidazo[2,l- ]thiazoles 366 (Equation 164) <1998J(P1)4093>. When using a-tosyloxyacetophenone, prepared by reaction of acetophenone with [hydroxyl(tosyloxy)iodo]benzene (HTIB), 5-aminopyrazole 367 could be converted to imidazo[l,2- ]pyrazole 368 in basic medium (Equation 165) <2005JHC209>. 

The reaction of 2-pyridylhydrazine and EMME in diphenyl ether at 190°C for 30 min give ethyl 5-hydroxy-l-(2-pyridyl)pyrazole-4-carboxylate in 6% yield (89MI435). 

The condensation products (1 1) of pentane-2,4-dione and 1,3-diphenyl-propane-1,3-dione with thiosemicarbazide, 4-methylthiosemicarbazide, and aminoguanidinium nitrate were formed (86KGS128 87ZOB584 90-KGS1260) as the cyclic isomers 78, which sometimes readily underwent dehydration to the corresponding pyrazoles. 

Castro GD, Lopez AJ, Petricio AR, etal. 1986. Effect of the pretreatment with pyrazole, cystamine or diphenyl-P-phenylenediamine (DPPD) on the CCKpromoted pentane evolution in rats. Res Common Chem Pathol Pharmacol 52 137-140. 

Bei der Umsetzung des 3,4-Dibenzoyl-furazan-2-oxids mit Phenylhydrazin entsteht wahrscheinlich 4,5-Bis-[hydroximino]-1,3-diphenyl-4,5-dihydro-1 H-pyrazol 5i 59 ... 

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