New Investigations in the Interrupted Nazarov Reaction

• Author / Creator

  Scadeng, Owen

• The five-membered carbocycle is a structural motif found in a plethora of natural products and bioactive compounds. The Nazarov reaction has emerged as an effective method to synthesize cyclopentenones and acts as a tool for adding structural complexity to molecular frameworks. This dissertation will discuss several projects involving the Nazarov cyclization and its use to build functionality to the cyclopentanoid framework.
  Chapter 1 provides a detailed recount of recent advances in Nazarov chemistry. Focus on methods to induce enantioselectivity, the use of alternative substrates as Nazarov reaction precursors, and the use of the Nazarov reaction in total synthesis is presented. Chapter 2 describes the formation of bridged bicyclic compounds via a [3+3]-cycloaddition between organoazides and the Nazarov intermediate. These cycloadducts were also found to thermally decompose to produce ring-enlarged dihydropyridones and 6-methylenepiperidinones.
  In Chapter 3, details the attempted development of a domino Nazarov cyclization/Baeyer-Villiger oxidation are provided. While the desired 3,4-dihydropyra-2-one was formed with the use of bis(trimethylsilyl)peroxide as the oxidant, optimization of the transformation failed to produce synthetically useful yields.
  Chapter 4 divulges the findings of Nazarov cyclizations of 2-hydroxyalkyl-1,4-diene-3-ones. Originally proposed as substrates that could undergo domino Nazarov cyclization/semipinacol rearrangements, these compounds were found to readily produce alkylidene cyclopentenones under Lewis acid conditions. These substrates provided insight into the effect that 2-hydroxyalkyl substituents have on the charge density of the oxyallyl cation intermediate of the Nazarov reaction and subsequent alkene formation.

• Subjects / Keywords

  • Cycloaddition
  • Synthesis
  • Azides
  • Methodology
  • Electrocyclization
  • Nazarov

• Graduation date

  Fall 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3RH4C

• 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.