Novel Method of Tetramic Acid Synthesis: Silver-Catalyzed Carbon Dioxide Incorporation into Propargylic Amine and Intramolecular Rearrangement

Tetramic acid derivatives have been studied as biologically active heterocycle structures for pharmaceutical or agricultural chemicals. Conventional preparative approaches often require highly functionalized starting materials and harsh heating conditions in basic media. The present report provides a conceptually new synthetic strategy for the synthesis of tetramic acid derivatives from easily available propargylic amines and carbon dioxide with a silver salt and DBU under mild reaction conditions

Efficient Preparation of 4‑Hydroxyquinolin-2(1<i>H</i>)‑one Derivatives with Silver-Catalyzed Carbon Dioxide Incorporation and Intramolecular Rearrangement

Although 4-hydroxyquinolin-2(1<i>H</i>)-one derivatives have attracted much attention due to their biological benefits, conventional reactions under harsh heat conditions must be employed to provide these key compounds. In the presence of a catalytic amount of silver salt, various <i>o-</i>alkynylanilines were treated with carbon dioxide and a base under mild reaction conditions to afford the corresponding 4-hydroxyquinolin-2(1<i>H</i>)-one derivatives in high yield

Silver-Catalyzed Incorporation of Carbon Dioxide into <i>o-</i>Alkynylaniline Derivatives

Benzoxazine-2-one derivatives are important heterocycle structures because of their various pharmaceutical activities, though their synthetic methods had been limited. In some cases, toxic reagents, such as phosgene or carbon monoxide, are required. It was found that a silver catalyst successfully promoted the incorporation of CO₂ into <i>o-</i>alkynylanilines to afford the corresponding benzoxazine-2-ones bearing <i>Z exo</i>-olefin via 6-<i>exo-dig</i> cyclization at the activated C–C triple bond