Studying On Visible Light-induced Oxidative Reaction: Easy Access To Oxazolones

The recent manifestation of the potential risk inherent to nuclear technologieshas incited a strong demand or exploration of innovative means to exploit energyfrom natural sources, thus increasing the need for research on sustainable energy inmany scientific fields. Chemists can contribute by developing chemical systems toutilize solar light, which is undoubtedly the best source of sustainable energyavailable on the planet. Another imperative issue is the establishment ofcarbon-neutral systems. One synthetic approach to this issue is the incorporation ofCO2into organic compounds as a chemical feedstock. High-energy compounds suitenergetically low CO2as the reaction partner. Under these circumstances, it presentsa significant challenge to simultaneously tackle the two issues mentioned above.Thus, we tried to synthesize oxazolones that is promoted by visible light and utilizesCO2as a chemical feedstock.We report herein a milder and convenient method to achieve oxazolones fromamines in the presence of gaseous carbon dioxide using carbon tetrabromide(CBr4)generated in situ, obtained by the base of2,6-lutidine in dry CH3CN. We haveoptimized the reaction conditions by the solvent, the gas atmosphere, the type ofbase and oxidant respectively. The reactions were accomplished using a2.0-foldmolar excess of2,6-lutidine and the same molar ratio of carbon tetrabromide withrespect to substrate in dry CH3CN. Generally, the reaction continued for5at roomtemperature until the completion of the reaction was indicated by TLC. The reactionwas then subjected to repeated preparative TLC on silica gel to afford the pureproduct. The yield up to86%.In order to explore whether the reaction apply generally, We take methylanthranilate or anthranilicvacid as the starting material which has successfullysynthesized26kinds of o-amino benzyl alcohol derivatives as light substrates.Under the optimal conditions, the derivates have got oxazolones whose yield is fromlow to high. It indicates that the reaction can apply universally.All the products exhibited physical and spectral data consistent with theirstructures.