Triplet-Triplet Energy Transfer in Organic Synthesis: Efforts toward a Chiral Lewis Acid Catalyzed De Mayo Reaction and Investigations of a Photoactive Ruthenium(polypyridyl)-NHC Complex

• Author / Creator

  Pearson, James William

• The fundamentals of energy transfer catalysis and its application in [2+2] photocycloadditions are thoroughly discussed.
  The De Mayo reaction is a UV light-promoted [2+2] photocycloaddition between enolic β-diketones and olefins that has been used to form α-substituted 1,5-diketones. Its introduction has enabled the assembly of complex macrocyclic scaffolds and been used as a key step in the synthesis of natural products. To address limitations imposed by direct UV light excitation the development of a visible-light variant(s) De Mayo reaction is essential. Herein, a report detailing a co-catalyzed system deploying the low-cost organic dye 4CzIPN in combination with a Lewis acid enables [2+2] photocycloaddition between β-diketones and styrenes to occur. Attempts toward an enantioselective De Mayo reaction via a chiral Lewis acid is also reported.
  In an effort to explore potential intramolecular energy transfer strategies the asymmetric imidazolium salt Ru(dmbpy)2(bpip)3 (bpip = 1-benzyl-3-isopropyl-1H-imidazo[4,5-f][1,10]phenanthrolinium), was prepared by a 4-step synthetic route. The isotopomer labelled with 13C at the C2 position of the bpip ligand was prepared from 1,10-phenanthroline-5,6-diamine and triethyl orthoformate-(formyl-13C). Deprotonation of the imidazolium salt at low temperatures in acetonitrile using KOtBu and KHMDS were monitored by NMR to investigate the formation of the free N-heterocyclic carbene.

• Subjects / Keywords

  • Organic Synthesis
  • Energy Transfer
  • Photocatalysis
  • Photocatalyst
  • cycloaddition
  • N-Heterocyclic Carbene

• Graduation date

  Fall 2021

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-gpt4-dj28

• 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.