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Reaction of ethyl or methyl 2-dimethylaminomethylene-3-oxoalkanoates 2 with phenylhydrazine gave the corresponding esters of 5-substituted 1-phenyl-1H-pyrazole-4-carboxylic acids 3 in high yields. Esters 3 were hydrolyzed to the relative carboxylic acids 4, which were converted by heating to 5-substituted 1-phenyl-1H-pyrazoles 5 in excellent yields. Reaction of methyl 5,5-dimethyl-3-dimethylaminomethylene-2,4-dioxohexanoate with phenylhydrazine afforded methyl 1-phenyl-4-pivaloyl-1H-pyrazole-5-carboxylate 8 b, which was converted as above to the corresponding carboxylic acid 10 b and this to 1-phenyl-4-pivaloyl-1H-pyrazole 11 b. Starting from 5-methoxymethyl-1-phenyl-1H-pyrazole, 1-phenyl-1H-pyrazole-5-acetic acid 18 and its alpha-methyl derivative 19 were also synthesized. Compounds 18, 19, 10 b and 11 b showed a strong antiinflammatory activity in rats; the same compounds in general as well as 8 b, showed appreciable analgesic and antipyretic activities in mice and rats, respectively.

Experimental research has documented that fenoverine is a depressant drug mostly active on the intestinal smooth muscle; however, it is also active on other tissues as well as on the genito-urinary tract. Fenoverine may be considered a synchronizer of smooth muscle effective in modulating the intracellular influx of calcium into the cell and its release from the intracellular pool. Fenoverine causes a reduction of the excitatory junction potential (EJP) in intestinal smooth muscle by stimulating parasympathetic efferent fibres without any change in the inhibitory junction potential (IJP). This also occurs in the presence of atropine. Fenoverine reduces the intracellular Ca2+ concentration by decreasing the calcium gradient across the cell membrane, as well as decreasing the release of Ca2+ from the intestinal pool more intensely than papaverine (but less intensely than nifedipine, verapamil or diltiazem). This phenomenon has been observed in the intestinal smooth muscle and also in the genito-urinary tract.