Synthesis Of Biaryls Via Palladium-Catalyzed Cross-Coupling Reactious Of Diazo Compounds,and Synthetic Studies Towards Subincanadine E And Maoecrystal V

This dissertation covers the synthesis of biaryls via palladium-catalyzed cross-coupling reactions of diazo compounds as well as the synthetic studies towards subincanadine E and maoecrystal V. It includes three chapters.In Chapter1, the synthesis of biaryls via tandem palladium-catalyzed cross-coupling/aromatization from diazo compounds is described. A novel palladium-catalyzed cross-couling reaction of diazo compounds to synthesize arylphenols has been successfully developed. Twenty-three examples were examined, and moderate to excellent yield have been achieved. The enantioselective version of this reaction has also been investigated, and the preliminary results showed that the coupling products could be generated in up to72%ee.Chapter2is focused on the synthetic studies towards subincanadine E. This indole alkaloid consists of an unprecedented azabicyclo[5.2.2]undecane framework and possesses in vitro cytotoxicities against murine lymphoma and human epidermoid carcinoma KB cells. A brief introduction of the isolation and biological activities of subincanadine E is described, and the relevant synthetic studies reported in the literature have been summarized. Four distinct strategies have been applied to the construction of the core structure of the target compound, including (ⅰ) Pd-catalyzed intramolecular allylation,(ⅱ) Pd-catalyzed intramolecular allylic Stille reaction,(ⅲ) Ni-catalyzed intramolecular Michael cyclization, and (ⅳ) allylic radical cyclization. Unfortunately, none of them led to the completion of total synthesis of this alkaloid.Chapter3deals with the synthetic studies towards maoecrystal V. This natural product features a novel C19diterpenoid possessing a unique6,7-seco-6-nor-15(8→9)-abeo-5,8-epoxy-ent-kaurane skeleton and has showed remarkable inhibitory activity toward HeLa cells. A brief introduction of the isolation and biological activities of maoecrystal V is described, and the relevant synthetic studies reported in the literature have been summarized. The advanced core structure3-100was chosen as our synthetic target. Lewis Acid-promoted cationic rearrangement of3-102and3-113was designed as the key transformation. Model studies were conducted, however, the undesired tricyclic lactone3-115was formed as the main product instead. In addition, compound3-119was synthesized by a palladium-catalyzed cross-coupling reaction of3-118and3-110; nevertheless, the subsequent key transformation of3-119into3-100has not been attempted yet.