Syntheses of Some Novel 1,3,4-Oxadiazole Derivatives and their Potential Biological Activity

A new Mannich base of quinazolin-4-one derivatives possessing 1,3,4-oxadiazole ring have been synthesized by reacting 3-[4-(5-thioxo-4,5-dihydro-[1,3,4]oxadiazole-2-yl)-phenyl]-2-phenyl-3H-quinazolin-4-one (4) with different secondary amines and formaldehyde using N,N-dimethylformamide as the solvent to afford 3-[4-(4-substituted amino4-ylmethyl-5-thioxo-4,5-dihydro-[1,3,4]oxadiazole-2-yl)-phenyl]-2-phenyl-3H-quinazolin-4-ones (5a–e). The structures of the newly synthesized compounds have been established by analytical and spectral methods. The compounds have also been screened for their biological activity. 5a–e