Enantioselective Synthesis of Coumarin Derivatives by PYBOX-DIPH-Zn(II) Complex Catalyzed Michael Reaction

A potential pharmacologically active chiral 3-substituted 4-hydroxy-2-oxo-2H-chromene skeleton has been synthesized by enantioselective Michael addition catalyzed by PYBOX-DIPH-Zn(OTf)(2) complex. The methodology has successfully been employed in the synthesis of (R) Warfarin and another related compounds.