A palladium-catalyzed intramolecular carbonylative annulation reaction for the synthesis of 4,5-fused tricyclic 2-quinolones.

A concise and efficient synthetic route to 4,5-fused tricyclic 2-quinolones through the palladium-catalyzed carbonylative annulation of alkyne-tethered N-substituted o-iodoanilines has been developed. This reaction proceeds smoothly under mild reaction conditions and exhibits exceptional tolerance to a variety of functional groups. It has been successfully applied to the efficient synthesis of BI 224436, an HIV integrase inhibitor.