Stereoselective Synthesis of 2,6-trans-Tetrahydropyran via Primary Diamine-Catalyzed Oxa-Conjugate Addition Reaction of α,β-Unsaturated Ketone: Total Synthesis of Psymberin

The total synthesis of psymberin was achieved employing a readily available chiral epoxide to prepare two of the three subunits in the natural product. The key reaction was a highly stereoselective organocatalytic oxa-conjugate addition reaction of alpha,beta-unsaturated ketone catalyzed by primary diamine for the synthesis of the 2,6-trans-tetrahydropyran embedded in psymberin.