Rhodium-Catalyzed ortho-Olefination of Sterically Demanding Benzamides: Application to the Asymmetric Synthesis of Axially Chiral Benzamides.

It has been established that an unsubstituted cyclopentadienyl rhodium(III) (CpRh ) complex is a highly active catalyst for the aerobic oxidative ortho C-H bond olefination of sterically demanding ortho-substituted benzamides with alkenes. This catalysis was successfully applied to the diastereoselective synthesis of axially chiral N,N-dialkylbenzamides. The combination of the ruthenium(II)-catalyzed enantioselective hydrogenation and the CpRh -catalyzed diastereoselective ortho C-H bond olefination enabled the asymmetric synthesis of axially chiral N,N-dialkylbenzamide derivatives with high ee values.