One-pot Synthesis of new azo-linked 4H-benzo[d][1,3]oxazine-2,4-diones from carbon dioxide using CuO@RHA/MCM-41 nanocomposite in green media

A series of azo-linked 4H-benzo[d][1,3]oxazine-2,4-diones were synthesized in excellent yields and short reaction time by one-pot reaction between various synthetized azo-linked carboxylic acids and carbon dioxide in the presence of CuO@RHA/MCM-41 nanocomposite as a novel catalyst at room temperature. This nanocomposite consists of CuO nanoparticles and MCM-41 matrix obtained from rice husk ash (RHA). The present methodology offers several advantages such as mild conditions, excellent yields, simple procedure and reduced environmental consequences. The catalyst was recovered and reused. The structures of the synthesized 4H-benzo[d][1,3]oxazine-2,4-dione compounds were confirmed by 1H, 13C NMR and FTIR spectral data and elemental analyses.