Ring expansion of 3-hydroxyoxindoles to 4-quinolones palladium-catalyzed C-C(acyl) bond cleavage.

We report herein the construction of 4-quinolones palladium-catalyzed regioselective β-acyl elimination of 3-hydroxyoxindoles and a subsequent Camps cyclization process. This protocol is highly efficient and various 4-quinolone derivatives are obtained in high yields. The construction of the core skeleton of the 4-quinolone antibiotics demonstrated the synthetic utility of this method.