An azo-bridged ring system enabled by-standing immobilization of a chiral diene ligand

A family of 9-azabicyclo[3.3.1]nonadienes were designed, prepared and successfully applied in the rhodium-catalyzed addition of arylboronic acids to N-tosylarylimines, affording chiral diarylmethyl amides with excellent enantioselectivities (up to 97% ee). The nitrogen atom in the bridged ring enabled a facile immobilization of diene ligands to silica. The obtained heterogeneous catalyst was evaluated in the above addition reaction and reused five times without significant loss in yield and enantioselectivity.