Rhodium‐Catalyzed Decarbonylative Direct C2‐Arylation of Indoles with Aryl Carboxylic Acids

Abstract

Abstract A Rh I ‐catalyzed direct C2‐arylation of indoles with diversely substituted aryl carboxylic acids has been developed using 2‐pyrimidyl group as an easily installable and readily removable N‐directing group. The reaction proceeded smoothly without the need for any external oxidants under relatively mild conditions to produce the C2‐arylated indoles in high yields with excellent regioselectivity. A range of functional groups in both coupling partners were tolerated regardless of their electronic properties and positions. With the assistance of the 2‐pyrimidyl group, these C2‐functionalized products could further undergo C7‐arylation to give the C7‐aryl indole products. Mechanistic evidence supports that the reaction involves a decarbonylation step, and the carboxylic acids could be activated in situ by treatment with ( t BuCO) 2 O to generate the active anhydrides.