| The synthetic studies toward the total syntheses of recently isolated bioactive natural products, haouamine A, platensimycin and platencin were investigated. During the course study of a new alkaloid, haouamine A, we have developed a simple synthetic route of chiral 2-substituted-3-piperidinones by utilizing a sequential regioselective proline-mediated aldol condensation and rhodium-catalyzed asymmetric hydrogenation. The model studies on aza-[7]-paracyclophane moiety of haouamine A were also examined with the strategies involving in Diels-Alder reaction, Ramberg-Backlund Reaction, cyclotrimerization, and Danheiser Benzannulation. In the studies of platensimycin and platencin, we intended to apply the pseudo-biomimeric cyclization strategy for the introduction of their characteristic bicyclo[2.3.1]octane and bicyclo[2.2.2]octane bridgehead structures. As a result, we have accomplished the concise total synthesis of platencin from commercially available o-anisic acid in 14 steps with 3.5% overall yield. During the course of this investigation, we developed a convenient method to synthesize the two distinctive cis-decalines containing a chiral quaternary carbon center through Diels-Alder reaction by utilizing two different sizes of amino-siloxyl dienes. We also found the modification of nickel mediated conjugate addition, discovered an unprecedented chemical reactivity of vinylsilane under oxidation condition with iodosobenzene and hydrogen peroxide, and demonstrated the biomimeric protective group free coupling strategy. |
