Development of Rh-Catalyzed Chemoselective Z-Olefin Synthesis and Ir- and Pd-Catalyzed Decarboxylative Enantioselective Benzylation

• Author / Creator

  Wei, Zhongyu

• Transition metal-catalyzed bond-forming reactions are powerful strategies in modern organic synthesis, which enable various functional group transformations and cross-coupling processes in a highly chemo-, regio- and enantioselective manner. Selectivity can be achieved through the appropriate choice of metal/ligand system, which facilitates the rapid buildup of molecular complexity. Thus, diverse methodologies based on transition metal catalysis have emerged and offer improved synthetic routes to pharmaceuticals and agrochemicals. This thesis describes the development of two selective transition metal-catalyzed bond-forming processes, which are positioned to help accelerate the discovery of next-generation functional small molecules.Z-olefins are useful synthetic units, yet difficult to prepare due to the relative thermodynamic instability compared to the E-isomer. Chapter 1 describes the chemo- and regioselective synthesis of Z-olefins through reduction on activated dienes, where the selectivity is driven by rhodium catalysis via stereospecific chelation. Formic acid serves as a cheap, safe and readily available hydrogen surrogate, showing its unique advantages in contrast with other hydride sources or hydrogen gas.Chapter 2 describes a highly enantioselective benzylation process using aryl acetic acids as benzylating reagents, catalyzed by cyclometallated iridium-phosphoramidite complex or palladium catalyst with Trost-type chiral ligand. This process shows dramatically improved scope and compatibility with protic and electrophilic functional groups, in contrast with established methods. As a result, this strategy provides novel synthetic routes to generate a class of valuable chiral organic molecules.

• Subjects / Keywords

  • decarboxylative functionalization
  • benzylation
  • transition metal catalysis
  • Z-olefin
  • stereoselective

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-ntzj-gp16

• License

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