Asymmetric synthesis of tetrahydropyran[3,2-c]quinolinones via an organocatalyzed formal[3+3]annulation of quinolinones and MBH 2-naphthoates of nitroolefin

An efficient asymmetric and enantio-swithchable organocatalytic[3+3]annulation reaction using MBH-2-naphthoates of nitroalkenes and 4-hydroxyquinolin-2(1H)-ones has been developed.Densely substituted tetrahydropyrano[3,2-c]qui noli nones scaffolds with two adjacent stereogenic centers are obtained with high yield(up to 95%yield)and good stereoselectivities(up to>20:1 dr and 96%ee)in an enantio-switchable manner.Furthermore,gram scale synthesis was achieved and the nitro group could easily transform into an amino group without any appreciable loss in the diastereo-and enantioselectivity.