Synthesis of Substituted 1,3,4 Oxadiazoles as Anti-inflammatory Agent.
A mixture of 4-hydroxyphenylacetic acid, absolute ethanol, few drops of concentrated sulfuric acid along with a small porcelain chip on reaction formed Ethyl-(4-hydroxyphenyl) acetate (1). On condensing mixture of 1, hydrazine hydrate and absolute ethanol formed 4-Hydroxyphenyl acetic acid hydrazide (2). Further mixture of 2, aryl/alkyl isothiocyanate and ethanol was refluxed and formed N1-[2-(4-Hydroxyphenyl) acetyl] N4-alkyl/aryl-3-thiosemicarbazide (3a-i). A suspension of (3a-3i) in ethanol, aqueous sodium hydroxide, iodine in potassium iodide solution refluxed for 3-5 hours on a water bath and formed 5-(4-Hydroxyphenyl) methyl-2-phenylamino-1,3,4-oxadiazole (4a-4i). A mixture of 5, potassium hydroxide and carbon disulphide in ethanol was refluxed and formed 5-(4-Hydroxyphenyl) methyl-2-mercapto-1,3,4-oxadiazole (4j). The oxadiazole derivatives of 4-hydroxyphenyl acetic acid (4a-j) showed anti-inflammatory activity ranging from 37.37% to 66.66% at 70mg/Kg oral dose after 4 hours, whereas the standard drug Ibuprofen showed 86.35% inhibition of rat paw edema at the same oral dose.
Meenakshi Virmani, and Sabir Hussain