ABSTRACT
Full details of the total synthesis of the Schisandraceae nortriterpenoid natural product rubriflordilactoneâ A are reported. Palladium- and cobalt-catalyzed polycyclizations were employed as key strategies to construct the central pentasubstituted arene from bromoendiyne and triyne precursors. This required the independent assembly of two AB ring aldehydes for combination with a common diyne component. A number of model systems were explored to investigate these two methodologies, and also to establish routes for the installation of the challenging benzopyran and butenolide rings.
Subject(s)
Schisandraceae/chemistry , Triterpenes/chemical synthesis , 4-Butyrolactone/analogs & derivatives , 4-Butyrolactone/chemistry , Catalysis , Cobalt/chemistry , Cyclization , Magnetic Resonance Spectroscopy , Palladium/chemistry , Schisandraceae/metabolism , Stereoisomerism , Triterpenes/chemistryABSTRACT
Two enantioselective total syntheses of the nortriterpenoid natural product rubriflordilactoneâ A are described, which use palladium- or cobalt-catalyzed cyclizations to form the CDE rings, and converge on a late-stage synthetic intermediate. These key processes are set up through the convergent coupling of a common diyne component with appropriate AB-ring aldehydes, a strategy that sets the stage for the synthetic exploration of other members of this family of natural products.
Subject(s)
Biological Products/chemical synthesis , Triterpenes/chemical synthesis , Biological Products/chemistry , Catalysis , Cobalt/chemistry , Cyclization , Kadsura/chemistry , Palladium/chemistry , Schisandra/chemistry , Stereoisomerism , Triterpenes/chemistryABSTRACT
Palladium-mediated cascade cyclisation reactions have been applied to the synthesis of the CDE-ring cores of two anti-HIV natural products, rubriflordilactone A and lancifodilactone G.