Reactions of 1,2-diphenylethane-1,2-dione hydrazone with 4-aryl-2-hydroxy-4-oxobut-2-enoic and 2-hydroxy-5,5-dimethyl-4-oxohex-2-enoic acids provided 4-aryl-4-oxo-2-[2-(2-oxo-1,2-diphenylethylidene)hydrazino]but-2-enoic and 5,5-dimethyl-4-oxo-2-[2-(2-oxo-1,2-diphenylethylidene)hydrazino]hex-2-enoic acids. The acids derivatives can exist in solutions as Z-and Ε-enehydrazino-or β-ketohydrazone forms, and under the treatment with acetic anhydride they undergo cyclization into 5-aryl-and 5-tert-butyl-3-[2-(2-oxo-1,2-diphenylethylidene)hydrazono]-2,3-furandiones.

Hydrazones derived from substituted benzophenones and fluorenone reacted with 4-aryl-2-hydroxy-4-oxobut-2-enoic and 2-hydroxy-5,5-dimethyl-4-oxohex-2-enoic acids to give the corresponding 2-(2-ylidenehydrazino) derivatives which may be used as initial compounds for the synthesis of 3-hydrazono-3H-furan-2-ones. The obtained but-2-enoic and hex-2-enoic acid derivatives in solution may exist as Z-and E-isomeric enehydrazine tautomers or hydrazone tautomers with syn or anti orientation of substituents with respect to the double C=N bond. * For communication V, see [1].

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hydrazino]but-2-enoic Acids. -The title compounds (III) exist in solution as Z-and E-enehydrazino-or β-ketohydrazone forms. On treatment with acetic anhydride, they undergo cyclization to furandiones (IV). -(KOMAROVA, O. A.; IGIDOV, N. M.; RUBTSOV*, A. E.; ZALESOV, V. V.; MAKAROV, A. S.; TOKSAROVA, Y. S.; Russ.