Pyrazolecarboxylic acids

When pyrazolecarboxylic acids (Section 4.04.2.3.3(iii)) are treated with thionyl chloride instead of the acid chloride, compound (254) is isolated. This corresponds to a double iV-acylation (67HC(22)1). 

TABLE XXV. Pyranopyrazoles Prepared by Cyclocondensation of vic-Iodo-pyrazolecarboxylic Acid with Copper(I) Acetylides [86TH1 78IZV1175 81IZV902 81IZV1342]. 

TABLE XXVI. Pyranopyrazoles Prepared by Cyclization of Vicinal (Alkyn-1-yl)pyrazolecarboxylic Acid [81IZV1342]. 

Arylmethylene)-5-phenyl-2(3/f)-furanones (22) react with nitrile imide 23, generated in situ, to give the spiropyrazones 24. The reaction was shown to be regioselective by and 13C NMR analysis of the reaction products. The spiropyrazoles 24 were converted by hydrolysis and methanolysis into the corresponding pyrazolecarboxylic acids 25 and car-boxylates 26, respectively (Scheme 7) [93JCR(S)80]. 

PECHMANN PYRAZOLE SYNTHESIS. Formation of pyrazoles from acetylenes and diazomethane. The analogous addition of diazoacetic esters to the triple bond yields pyrazolecarboxylic acid derivatives. 

H-Pyrazole-3-carboxylic acid, 4,5-dihydro-5-oxo-l-(4-sulfophenyl)-4-[(4-sulfophenyl)azo]-trisodium salt — see Tartrazine Pyrazole-5-carboxylic acid, 4-hydroxy-synthesis, 5, 276 Pyrazolecarboxylic acids decarboxylation, 5, 260 reactions... 

Pyrazolecarboxylic acids (plsTa (66RTC1195)) are readily decarboxylated and this provides a method for introducing a deuterium atom into the pyrazole ring. 3-Deuteroindazole has also been prepared in this way (76CJC1329). Lithium aluminum hydride reduces 3-ethoxycar-bonyl-3 (5 ),5-dimethyl-5 (3 )-pyrazol-l-ylpyrazole (440 R = C02Et) to the corresponding alcohol (440 R = CHjOH) <81T987>. 

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. 

Halo-5-pyrazolecarboxylic acids were prepared as outlined in Figure 5 as shown for the bromo derivative 32. Treatment of 27 with n-butyllithium at -60 °C in THF followed by bromination with dibromotetrachloroethane afforded the pyrazole 28 [8]. Removal of the N,N-dimethylsulfamoyl protecting group afforded... 

The pyrazole is then chlorinated in the 4 position and saponified to give the pyrazolecarboxylic acid. The acid chloride of the pyrazolecarboxylic acid is formed and coupled with 4-tert-butylbenzylamine or 4- p-tolyloxy)benzylamine to give tebufenpyrad and tolfenpyrad, respectively. The side chain compound 4-tert-butylbenzylamine is prepared by the reductive amination of 4-tert-butylbenzal-dehyde with aqueous ammonia. The compound 4-(p-tolyloxy)benzylamine is prepared by coupling 4-fluorobenzonitrile with sodium p-cresol followed by reduction with Raney nickel in aqueous ammonia [47, 48]. 

A mixture of 4.0 g. 1-phenyl-4,5-dichloro-6(lH)-pyridazinone and 5%-NaOH heated 5 hrs. at 130° 2.2 g. l-phenyl-3-hydroxy-5-pyrazolecarboxylic acid. Y. Maki and K. Obata, Ghem. Pharm. Bull. 12, 176 (1964). 

Dang Q, Liu Y, Sun Z (2001) A tandem decarboxylation/Diels-Alder reaction of 5-amino-l-phenyl-4-pyrazolecarboxylic acid with 1,3,5-triazines. Tetrahedron Lett 42 8419-8422... 

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