Reactions of arene-and pyridinecarbaldehydes with ferrocenyl-4,5-dihydropyrazoles afforded 1-arylmethyl-and 1-pyridylmethyl-3,5-aryl(ferrocenyl)pyrazoles. Their structures were established based on spectroscopic methods and, for 4-[(3,5-diferrocenylpyrazol-1-yl)methyl]pyridine, based on X-ray diffraction analysis.

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Organo-iron compounds S 7100Synthesis of Ferrocenylpyrazole Derivatives. -The reactions of pyrazolines (II) and (VI) with aromatic aldehydes are studied aiming at the development of a convenient method for the synthesis of ferrocenylpyrazoles. The reaction of (II) and (VI) with aldehydes (III) and (VII) occurs as an intramolecular oxidation of the pyrazoline ring into pyrazole with concomitant reduction of an exocyclic functionality into the methylene group. Sufficiently high antiviral activities are shown by ferrocenylpyrazoles (IVc)-(IVe), (VIIIa), (VIIIb) and anti-inflammatory activities by compounds (IVa),, (VIIIb) and (VIIIc). -(KLIMOVA*, E. I.; VAZQUEZ LOPEZ, E. A.; KLIMOVA, T.; J. Heterocycl. Chem. 42 (2005) 2, 265-271; Fac. Quim., Univ. Natl. Auton. Mex., Coyoacan, 04510 Mexico, Mex.; Eng.) -H. Hoennerscheid 33-200

Monocyclic 3-and 5-ferrocenyl-4,5-dihydropyrazoles with a free NH group in the molecule react with acetylacetone to form the corresponding enaminocarbonyl compounds. The latter were isolated as a single isomer, presumably E. 3-Ferrocenyldihydropyrazoles and 5-ferrocenyl-3-(p-methoxyphenyl)-4,5-dihydropyrazole analogously react with acetoacetic ester. 5-Ferrocenyl-3-phenyl-, 3-(p-bromophenyl)-5-ferrocenyl, and 3,5-diferrocenyl-4,5-dihydropyrazoles react with acetoacetic ester to form acetoacetylpyrazolides.