Ligand-Controlled Palladium(II)-Catalyzed Regiodivergent Carbonylation of Alkynes: Syntheses of Indolo[3,2-c]coumarins and Benzofuro[3,2-c]quinolinones

Regiodivergent syntheses of indolo[3,2-c]coumarins and benzofuro[3,2-c]quinolinones through a controllable palladium(II)-catalyzed carbonylative cyclization are established. The chemo- and regioselectivity are exclusively tuned by the ligand on the palladium catalyst. The rigid framework of the electron-deficient ligand promotes the O-attack/N-carbonylation cyclization leading to benzofuro[3,2-c]quinolinones, while a sterically bulky and electron-rich ligand facilitates N-attack/O-carbonylation cyclization to generate indolo[3,2-c]coumarins. Furthermore, various other nucleophiles are applicable for delivering a variety of indoloquinolinones, pyranoquinolones, and chromeno[3,4-c]quinolinones in one step, and serves as a method for creating compound libraries for drug discovery.