No abstract

The cyclization at the treatment of acetic anhydride of 4-aryl-2-arylamino-4-oxobut-2-enoic and 2-arylamino-5,5-dimethyl-4-oxohex-2-enoic acids was investigated furnishing derivatives of 5-aryl-3-aryl-imino-3H-furan-2-ones and 4-arylamino-2-tert-butyl-2,5-dihydro-5-oxofuran-2-yl acetate respectively. 2-N 2 -Methylenesubstituted 4-aryl-2-hydrazino-4-oxobut-2-enoic and 5,5-dimethyl-2-hydrazino-4-oxohex-2-enoic acids cleanly underwent cyclization under the effect of acetic anhydride into 5-aryl-3-hydrazono-3H-furan-2-ones and 5-tertbutyl-3-hydrazono-3H-furan-2-ones.The analysis of published data shows that iminofuranones are available and convenient compounds for preparation of versatile acyclic and heterocyclic structures [2][3][4][5][6]. The application of iminofuranones in synthetic procedures requires an existence of a convenient method for their preparation with the possibility of substituents variation. We formerly developed a method of the synthesis of N-substituted 5-aryl-3-imino-3H-furan-2-ones consisting in the intramolecular cyclization of N-substituted 2-amino-4-aryl-4-oxobut-2-enoic acids [7-9] and providing a possibility of variation in a relatively wide range of substituents both at the imine nitrogen and the position 5 of the furan ring.To test the potential of this method and to increase the versatility of substituted 3-imino-3H-furan-2-ones we formerly synthesized N-substituted 2-amino(hydrazono)-4-aryl-4-oxobut-2-enoic and 2-amino(hydrazono)-5,5-dimethyl-4-oxohex-2-enoic acids and investigated their tautomeric rearrangements [1,10].

Acids. -All compounds are purified by recrystallization from an aprotic, non-polar solvent like toluene and hexane. -(TYUNEVA, A. V.; IGIDOV, N. M.; KORYAGINA, N. N.; BORODIN, A. Y.; ZAKHMATOV, A. V.; MAKAROV, A. S.; TOKSAROVA, Y. C.; RUBTSOV*, A. E.; Russ. J. Org. Chem. 47 (2011) 2, 258-264, http://dx.doi.org/10.1134/s1070428011020163 ; Perm State Univ., Perm 614990, Russia; Eng.) -G. Mueller 33-090