Synthesis, Structure Activity Relationship Studies and Pharmacological Evaluation of 2-Phenyl-3-(Substituted Phenyl)-3H-Quinazolin-4-ones as Serotonin 5-HT2 Antagonists

Benzoyl chloride was added to the solution of anthranilic acid in pyridine to afford crude 2-phenyl-benzo[d][1, 3] oxazin-4-one (1). To the solution of compound 1 in dry toluene, various substituted anilines were added and the mixture refluxed for 8 h to afford 2-phenyl-3-(substituted phenyl)-3H-quinazolin-4-ones (2a-2f). All the compounds were obtained in solid state in yields varying between 40 to 70%. Spectral characterization included FTIR, (1)H NMR and Electrospray MS. The synthesized compounds were screened for 5-HT(2) antagonist activity. Some of the title compounds have been found to show significant 5-HT(2) antagonist activity. The compound 2b, 3-(2-chlorophenyl)-2-phenyl-3H-quinazolin-4-one was the most potent derivative in the series of compound synthesized.