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-2<i>H</i>-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 (<i>R</i>)-Warfarin and another related compounds.