Silver-catalyzed incorporation of carbon dioxide into o-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 CO(2) into o-alkynylanilines to afford the corresponding benzoxazine-2-ones bearing Z exo-olefin via 6-exo-dig cyclization at the activated C-C triple bond.