3-Oxobutanamides in Heterocyclic Synthesis: Synthesis, Antimicrobial and Antioxidant Activity of Pyridine, Thiophene, Diazepine and Thiazole Derivatives

Abstract

In the last few years we and others reported a variety of synthesis of heteroaromatics that have been developed utilizing β–oxoanilides as readily obtainable compounds. In this study, treatment of 3-Oxobutanamides 1 with phenyl isocyanate at room temperature in basic medium and DMF afforded thiocarbamoyl derivative 3 through intermediate 2 upon treatment with dilute HCl. The non-isolable potassium salt 2 was allowed to react with α-halo carbonyl compounds such as ethyl chloroacetate and chloroacetonitrile in dry DMF at room temperature to furnished thiophene 6 and thiazole derivative 9 respectively. Compound 6 was treated with hydrazine hydrate in ethanol to yield thiophene-5-carbohydrazide derivative 7. Also, compound 1 reacted with malononitrile and sulfur element in refluxing absolute ethanol and triethylamine to yield thiophene derivative 11, which reacted with formic acid and α-chloro acetylchloride to give thieno[2,3-d]pyrimidine derivative 12 and chloro acetamide derivative 13. Treatment of compound 13 with ammonium thiocyanate led to thiazolo[3,2-a]thieno[2,3-d]pyrimidine derivative 15 through non-isolable 14. Also, condensation of 1 with malononitrile and ethylene diamine afforded the pyridine derivative 17 and 1,4-diazepine derivative 18. The structures and formulas of all the synthesized compounds were supported by spectral data. Some of the synthesized compounds were evaluated for their antibacterial and antioxidant activity. These compounds showed different degrees of activity.