Rhodium-Catalyzed Alkylation of C−H Bonds in Aromatic Amides with Non-activated 1-Alkenes: The Possible Generation of Carbene Intermediates from Alkenes

The alkylation of C−H bonds (hydroarylation) in aromatic amides with non-activated 1-alkenes using a rhodium catalyst and assisted by an 8-aminoquinoline directing group is reported. The addition of a carboxylic acid is crucial for the success of this reaction. The results of deuterium-labeling experiments indicate that one of deuterium atoms in the alkene is missing, suggesting that the reaction does not proceed through the commonly accepted mechanism for C−H alkylation reactions. Instead the reaction is proposed to proceed through a carbene mechanism. The carbene mechanism is also supported by preliminary DFT calculations.