Enantioselective synthesis of polycyclic coumarin derivatives catalyzed by an in situ formed primary amine-imine catalyst.

A facile in situ formed primary amine-imine organocatalyst was developed in the asymmetric Michael addition of substituted 4-hydroxycoumarins to cyclic enones. A series of optically active polycyclic coumarin derivatives were obtained in high yields with excellent enantioselectivities up to 97% ee.
(© 2011 American Chemical Society)