3- Aryl -5-trifluoromethyl-177-pyrazoles

A similar situation prevails with C-trifluoroacetylated arylaldehyde A,A-dimethyl-hydrazones (197 R = Me, R = H) which in trifluoroacetic anhydride and pyridine yield only l-alkyl-4-aryl-3-(trifluoromethyl)pyrazoles (205) <88TL5281>, while in the absence of pyridine the isomeric 5-aryl-3-methyl-4-(trifluoroacetyl)-6-trifluoromethyl-3,4-dihydro-2/7-oxadiazines (204 R = Ar) are formed in 40-76% yield <90TL1183>. 

A large variety of newer poly(ether imide)s has been described. Included among these are perfluorinated polymers (96), poly(ester ether imide)s (97), poly(ether imide)s derived from A/,Ar-diamino-l,4,5,8-naphthalenetetracarboxyHcbisimide (98), and poly(arylene ether imide ketone)s (99). In addition, many other heterocyHc groups have been introduced into polyether systems, eg, poly(pyrazole ether)s (100) and poly(aryl ether phenylquinoxaLine)s (101) poly(aryl ether oxazole)s with trifluoromethyl groups (102) and polyethers with other heterolinkages, eg, poly(arylether azine)s (103). 

A series of 2-(5-aryl-3-styryl-4,5-dihydro-lA-pyrazol-l-yl)-4-(trifluoromethyl)-pyrimidines 78 was synthesized by the cyclocondensation of 5-aryl-l-carboxamidino-3-styry 1-4,5-dihydro-1 //-pyrazoles 76 with 4-alkoxy-l,l,l-trifluoroalk-3-en-2-ones 77 <06S2349>. 

The most common method for the preparation of pyrazoles from other heterocycles is from pyranone-type compounds. Condensation of 2,3-dihydro /7-pyran -ones 787 with various aryl hydrazines in the presence of montmorillonite KSF clay under mild conditions proceeded rapidly to afford enantiomerically pure 5-substituted pyrazoles 788 (Equation 172) <2004TL6033>. Comparable results were obtained when arylhydrazines were reacted with 2-formyl glycals under microwave irradiation <2004TL8587>. Phenylhydrazine and hydrazine were reacted with 3-acetyl-4-hydroxy-6-methyl-2/7-pyran-2-one to afford 4-acetoacetyl-3-methylpyrazolin-5-ones, which were employed in the synthesis of bipyrazoles and pyrazoloisoxazoles <1999JHC1291>. Reaction of 3,3-dialkyl-6-(trifluoromethyl)-2,3-dihy-dro -pyrones with hydrazine hydrate afforded 3-(trifluoromethyl)-5-substituted-pyrazoles <1998RCB1365>. 

Based on the high levels of activity obtained for DIO, a series of N-pyridyl analogs were explored. We also wished to study the effect of substituents R4 on the aryl portion of the anthranilic diamide. Figures 4-6 illustrate the routes by which these compounds were prepared [2]. The method presented in Figure 4 was used to prepare the 3-trifluoromethyl-5-pyrazolecarboxylic acid 26. This method involves regioselective lithiation of 3-trifluoromethylpyrazole 25 followed by reaction with carbon dioxide, to afford the pyrazole carboxylic acid 26 in good yield. 

Palladium-catalyzed reaction of 5-aryl-2-(trifluoromethyl)furan-3-carbonyl chloride 263 with phenylacetylene afforded derivative 264 which is a convenient precursor for synthesis of pyrazoles, pyrimidines, and other heterocyclic systems bearing trifluoromethylated furan as substituent [154]. 

Bonacorso HG, Martins DB, Martins MAP, Zanatta N, Flores AFC (2005) Synthesis of alkyl-, aryl- and heteroaryl-substituted 2-[3-oxo-2,3-dihydro-lH-pyrazol-2-yl]-6(4)-trifluo-romethylpyrimidines from beta-alkoxyvinyl trifluoromethyl ketones. Synthesis 5 809-813... 

Shelke et al. [80] S5mthesized various fluorine-containing compounds by conventional and nonconventional procedures by ultrasonication and microwave techniques. Various 3-substituted-l-phenyl-lH-pyrazole-4-carbaldehydes were treated with 3-(trifluoromethyl)-l-phenyl-lH-pyrazol-5(4H)-one (83) to give 4-((3-(4-aryl)-l-phenyl-lH-pyrazol-4-yl) methylene)-3-(trifluoromethyl)-l-phenyl-lH-pyrazol-5(4H)-one (85). Equivalent mole of 3-formylchromone and 3-(trifluoromethyl)-l-phenyl-lH-pyrazol-5(4H)-one by conventional method and nonconventional methods gave 3-(trifluoromethyl)-4-(4-oxo-4H chromon-3-yl)-methylene-l-phenyl-lH-pyrazol-(4H)-one (84) (Scheme 21). Compounds 84 and 85 were obtained in slightly better yields within 5-10 min under ultrasonication than in 2-3 min with microwave irradiation. 

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