Synthesis of (±)-cis-Clavicipitic Acid by a Rh(I)-Catalyzed Intramolecular Imine Reaction

A new and short synthesis of racemic cis-clavicipitic acid was achieved by taking advantage of the double nucleophilic character of indole-4-pinacolboronic ester. Key to the success of the synthesis were an efficient and selective C-3 indole Friedel-Crafts alkylation and the development of an unprecedented intramolecular rhodium-catalyzed 1,2-addition of an aryl pinacolboronic ester to an unactivated imine.