Metal Complex-/Lewis Acid-Catalyzed C-C Bond Forming Reactions For Synthesis Of Functionalized Alkenes

Accessing higher alkenes from abundant and inexpensive petrochemical feedstocks has been shown to be a very powerful and versatile method for the synthesis of functionalized alkenes. Metal complex and Lewis acid-catalyzed carbon-carbon bond-forming reactions are among the most important types of functionalized alkene constructions in organic chemistry, especially palladium-catalyzed dimerization of vinylarenes and Heck reaction. Total synthesis of complex natural products not only embodies the achievement of contemporary organic chemistry and the art of chemical synthesis, but it also has been the driving force for development of new catalysts (for homodimerization of alkenes, olefin metathesis and so on). This thesis research focuses on three topics:(a) synthesis of novel carbocycle carbene-palladium complexes and their application in Heck reaction and Suzuki-Miyaura reaction; (b) highly efficient and selective In(OTf)3-catalyzed heterodimerization of vinylarenes; and (c) attempt to assembly of the trisubstituted (12E)-double bond of Amphidinolide X using the temporary diester-tethered ring-closing metathesis (RCM).Chapter 1 briefly introduces the known strategies for accessing functionalized alkenes from simple alkenes. The progress in Heck reaction, Suzuki-Miyaura reaction, Hydroalkenylation reaction and olefin metathesis is illustrated, covering advancements in the reaction mechanisms, different types of substrates, development of catalysts and applications in organic synthesis.Chapter 2 presents our studies on synthesis of novel carbocycle carbene-palladium complexes and their application in Heck reaction and Suzuki-Miyaura reaction under aerobic conditions after a short overview on carbene ligands for palladium-catalyzed cross-coupling reactions. Different types of carbocycle carbene-palladium complexes have been synthesized for the first time, using steric hindrance of biphenyl nitrones to facilitate selective C-H activation. These novel palladium complexes are thermally stable, neither air-sensitive nor moisture-sensitive, and efficient for aerobic reactions. After optimizing reaction conditions including temperature, solvent, time and loading of catalysts, a series of Heck and Suzuki-Miyaura reaction products are obtained in high yields.Chapter 3 describes In(OTf)3-catalyzed heterodimerization of vinylarenes after briefing the reports in the literature on head-to-tail dimerization of vinylarenes. A general and efficient hydroalkenylation of vinylarenes has been established, through addition of an olefinic C-H bond of 1,1-diarylethenes to vinylarenes catalyzed by In(OTf)3 to furnish the trisubstituted alkenes in good to excellent yields. The highly chemo- and regioselective head-to-tail heterodimerization likely takes place through a cationic mechanism initiated by the indium-bound carbocation. Our results present a new entry for highly selective alkene heterodimerization without replying on the action of transition metals.Chapter 4 describes an attempted investigation on improved total synthesis of Amphidinolide X. The structures of Amphidinolides and the known strategies used in the literature for total synthesis of Amphidinolide X are given with an emphasis on formation of the trisubstituted double bond. It is followed by a brief overview on the temporary tethered RCM for application in total synthesis of natural products. The attempted scheme for total synthesis of amphidinolide X and the investigation on formation of trisubstituted olefin via the temporary diester-tethered RCM are presented. Formation of the undesired (12Z)- Amphidinolide X is discussed.The main experimental procedures, the characterization data for the key compounds, and the cited references are found at the end of the thesis. Copies of the original 1H and 13C NMR spectra, and the data of X-ray single crystal structural analysis are given in the Appendix.