Synthesis of some biologically active 5-benzylidene-2-aryl-5,6- dihydro-4H-[1,3]oxazin-6-ones and 4-benzylidene-1-aryl-3,4- dihydropyrimidobenzimidazoles with bridged nitrogen

Abstract

Facile synthesis of differently substituted 5-benzylidene-2-aryl-5,6- dihydro-4H-[1,3]oxazin-6- ones 2a-2h has been achieved by heating a mixture of substituted N-benzoyl-β-aminopropanoic acids 1a-1d with several aromatic aldehydes in the presence of sodium acetate and acetic anhydride. These compounds 2a-2h, on refluxing with o-phenylenediamine in dry benzene resulted in the formation of differently substituted 4-benzylidene-1-aryl-3,4- dihydropyrimidobenzimidazoles 3a-3h. The synthesized compounds 2a-2h and 3a-3h were characterized by elemental analysis and spectral studies (IR, 1H NMR and 13CNMR).