SOLID SiO2-H3PO4 IS AN EFFICIENT CATALYST FOR CYCLIZATION OF ENONES UNDER SOLVENT-FREE CONDITION: SYNTHESIS AND ANTIMICROBIAL ACTIVITIES OF SOME OXAZINE DERIVATIVES

Abstract

ABSTRACT A series of some 1, 3-oxazine amine derivatives including 4-(1-naphthyl)-5,6-dihydro-6-(substituted phenyl)-oxazine-2-amines has been synthesised by solid SiO 2 -H 3 PO 4 catalyzed solvent-free cyclization of aryl chalcones and urea under microwave irradiation. The yields of the oxazines were more than 80%. The synthesised oxazine amines were characterized by their physical constants, analytical and spectroscopic data. The antimicrobial activities of these oxazine derivatives have been studied using Bauer-Kirby method. Key words: Oxazine amines, Enones, SiO 2 -H 3 PO 4 , Solvent-free synthesis. e-mail:drgtnarayanan@gmail.com INTRODUCTION The unsaturated oxazine and its derivatives are important bio-active six membered heterocyclic compounds possess one oxygen and one nitrogen atom 1 . Depending upon the relative position of these tow atoms and the double bond, they shows some isomeric structures such as 1, 2 or 1, 3 or 1, 4 oxazines 2 . These oxazines were medicinally important due to the presence of oxygen, nitrogen heteroatoms along with a double bonds in their structural moieties