Investigation of new ways to generate and capture transient cyclic allenes

• Author / Creator

  Constantin, Marius-Georgian

• Transient cyclic allenes are strained reactive intermediates currently underexploited in the synthetic organic field. Although there are several literature-known ways to generate and capture cyclic allenes, there is still room for new complementary methods to be developed. This thesis will discuss new ways to generate several cyclic allenes through lithium- and magnesium-halogen exchange promoted elimination. A new way of trapping electron-deficient cyclic allenes through a hetero-Diels–Alder cycloaddition will also be presented.
  In Chapter 1, cyclic allenes will be discussed in the larger context of reactive intermediates. This review will also introduce notions about the properties, methods to generate and the chemical behavior of cyclic allenes. Several recent results present in the literature will showcase the current research direction in this area.
  In Chapter 2, the results regarding new ways to generate several cyclic allenes through lithium- and magnesium-halogen exchange promoted elimination will be discussed. The typical dimerization and trapping of cyclic allenes were examined under these new conditions. Our investigation revealed that lithium-halogen exchange provided access to a series of dimers. Based on the initial findings with lithium halogen exchange, we developed an improved method using magnesium-halogen exchange, which offered access to specific trapping products and dimers.
  In Chapter 3, an investigation on the generation of electron-deficient cyclic allenes through base-promoted elimination will be presented. An unprecedented mode of dimerization of cyclic allenes was discovered. We later developed a new way of trapping electron-deficient cyclic allenes with enamines through a hetero-Diels–Alder cycloaddition. This novel trapping provided access to several structurally complex polycyclic products.
  Chapter 4 will discuss the research efforts to find a new method to generate C-acylimine reactive intermediates using a manganese (III) one-electron oxidizing agent. This discussion will focus on obtaining a single diastereomer isolated product during those efforts and my attempt to explain the formation of that product.
  Chapter 5 will provide a set of conclusions and possible future research plans for each of the projects presented in this thesis.

• Subjects / Keywords

  • enamines
  • cyclic allenes
  • 1,2-cyclohexadiene
  • hetero-Diels–Alder
  • Diels–Alder
  • lithium-halogen exchange
  • magnesium-halogen exchange

• Graduation date

  Fall 2021

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-0dhn-3002

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.