General Papers ARKIVOC 2008 (xvii) 295-305
Synthesis, azo-hydrazone tautomerism and antitumor screening of N-(3-ethoxycarbonyl-4,5,6,7-tetrahydro-benzo[b]thien-2-yl)-2arylhydrazono- 3-oxobutanamide derivatives
Thoraya A. Farghaly* and Zeinab A. Abdallah
Department of Chemistry, Faculty of Science, University of Cairo, Giza, Egypt E-mail:
[email protected]
Abstract
A series of new N-(3-ethoxycarbonyl-4,5,6,7-tetrahydrobenzo[b]thien-2-yl)-2-aryl hydrazono-3oxobutanamide derivatives 4a-i were synthesized and the acid dissociation constants (pKas) for the series prepared were determined and correlated by the Hammett-type equation using the enhanced substituent constants sx-. The results of such correlation together with the spectral data indicated that the studied compounds exist predominantly in the hydrazone tautomeric form. Some of these derivatives exhibit high antitumor activity.
Keywords: Synthesis, coupling, azo-hydrazone tautomerism, benzo[b]thiophene
Introduction
Azo dyes are versatile compounds that have wide applications in industry and photodynamic therapy as well as photosensitive species in photographic or electrophotographic systems and are dominant organic photoconductive materiels.1 Furthermore, thiophenes and their fused derivatives have shown diverse pharmacological activities including antibacterial,2,3 antifungal,3 immunomodulatory,4 antidiabatic,5 antiinflammantory,6 antiviral activities7,8 and anticancer agent.9 Therefore, it was thought to be of interest to combine two of the above-mentioned azo dye and thiophene ring together in a molecular framework to give dye with high pharmaceutical potentiality.
Results and Discussion
The required starting active methylene compound 3 was previously prepared10 as a mixture in 15-20% yield, but in this study we synthesized it by the condensation of compound 1 with ethyl acetoacetate 2 at 160 °C for 30 min. to give compound 3 in 95% yield (Scheme 1). Compound 3
ISSN 1551-7012 Page 295 ©ARKAT USA, Inc.
