B(C6F5)3‐Catalyzed Aza‐Friedel–Crafts Reaction of Indolizines with 2‐Aryl‐3H‐indol‐3‐ones

Abstract A Friedel–Crafts reaction of indolizines with 2‐aryl‐3 H ‐indol‐3‐ones catalyzed by B(C 6 F 5 ) 3 is described. This protocol gives access to indolizine derivatives that are valuable building blocks in synthetic and pharmaceutical chemistry. The reaction proceeds under mild conditions, affording various C2‐quaternary indolin‐3‐ones based on indolizine with high yields and regioselectivities. Moreover, the synthetic transformations of the target products were realized by N‐methylation and trifluoromethane sulfonation.