Asymmetric ring-opening reactions of azabenzonorbornadienes through transfer hydrogenation using secondary amines as hydrogen sources: tuning of absolute configuration by acids

Reductive transfer hydrogenation of bicyclic alkenes has been developed under the co-catalytic system of palladium and silver by using secondary amines as reductants. The reaction results in the asymmetric ring-opening product. A wide range of azabenzonorbornadienes reacted well giving 1,2-dihydronaphthalen-1-amine derivatives in high yields with good enantioselectivities. The control of the absolute configuration of the product by addition of carboxylic acids has been demonstrated.