Synthesis, Evaluation of Analgesic and Anti-inflammatory Activities of Substituted 1,2-benzoxazolone and 3-chloro-1,2-benzoxazole Derivatives

Herein method for the synthesis of substituted 1,2benzoxazolone (8a-f) and 3-chloro-1,2-benzoxazole (9a-f) derivatives has been described. A new scheme has been adapted for the construction of 1,2benzoxazole ring from salicylic acid and its derivatives which leads to the formation of series of 5,6 and 7 substituted title compounds. Synthesized compounds were characterized by IR, 1 H-NMR and Mass spectral analysis. Spectral data confirmed the compounds formation. Final compounds (8a-f) and (9a-f) were screened for their in-vivo analgesic activity by acetic acid induced writhing method in rats and anti-inflammatory activity by carrageenan-induced paw edema model. Among the compounds screened compound 8a and compound 9c showed good analgesic activity of about 45% (writhing mean 8.9) and 54% (writhing mean 7.5) inhibition respectively at 5 mg/Kg po dosage. Compounds 8b and 9b (both having inhibition edema of 66.1%) showed significant anti-inflammatory activity. Other derivatives exhibit moderate to good analgesic and anti-inflammatory activities. INTRODUCTION: Benzoxazole derivatives are highly potent and extremely useful in medicinal, industrial and pharmaceutical fields. These compounds have received considerable attention during last few decades as they are endowed with variety of biological activities and have wide range of therapeutic properties with low toxicity.