Synthesis, anti-HSV-1, and cytotoxic activities of some new pyrazole- and isoxazole-based heterocycles

摘要

Abstract Ethyl 2,4-dioxo-4-(p-chloro)phenylbutyrate 2 obtained by condensation of 4-chloroacetophenone with diethyl oxalate was converted to 5-(4-chlorophenyl)-1-phenyl-1H-pyrazole-3-carbohydrazide 5 and 5-(4-chlorophenyl)isoxazole-3-carbohydrazide 6 in good yields. Treatment of 5 or 6 with phenylisothiocyanate and reaction of the resulting thiosemicarbazide 7 or 8 with chloroacetic acid and 4-fluorobenzaldehyde, phenacyl bromides gave the corresponding 4-thiazolidinone 9 or 10 or 1,3-thiazoles 11 or 12, respectively. While the intramolecular cyclization of 7 or 8 in concentrated sulfuric acid afforded 1,3,4-thiadiazoles 13 or 14. The reactivity of hydrazide 5 or 6 towards fluorinated aldehyde, hydrazonoyl chloride, and β-ketoester was studied to give fluorinated hydrazones, bis-hydrazones, and pyrazoles 15–23. The newly synthesized compounds were screened for their antiviral activity, and compound 19 reduced the number of viral plaques of Herpes simplex type-1 (HSV-1) by 69%. The detailed synthesis and spectroscopic and biological data are reported.