Pd(II)‐Catalyzed C3‐Alkylation and Annulation of Indole‐2‐carboxamides with Maleimides: Access to Fused β‐Carbolinone Frameworks

Abstract A temperature‐controlled oxidative addition and annulation of maleimides onto 1H‐indole‐2‐carboxamides has been developed to the synthesis of angularly fused β‐carbolinone frameworks using Pd(OAc) 2 as a catalyst and Cu(OAc) 2 as a co‐oxidant. It is a novel and atom‐economical method for the one‐pot synthesis of highly functionalized β‐carbolinones. It is a modular approach to the synthesis of 3‐(indol‐3‐yl)maleimides and beta‐carbolines by mere change in temperature. This method offers several advantages such as operational simplicity, cleaner reaction profiles, wide substrate scope and high functional group tolerance. This is first report on the synthesis of highly functionalized β‐carbolines through a C─H bond activation of 1H‐indole‐2‐carboxamides.