University of Illinois Urbana-Champaign

Iron-catalyzed C—H alkylation and photoredox frontal ring opening metathesis polymerization

Wendell, Chloe Irene

Content Files
WENDELL-DISSERTATION-2021.pdf

Permalink

https://hdl.handle.net/2142/117883

Description

Title
Iron-catalyzed C—H alkylation and photoredox frontal ring opening metathesis polymerization
Author(s)
Wendell, Chloe Irene
Issue Date
2021-07-07
Director of Research (if dissertation) or Advisor (if thesis)
Moore, Jeffrey S.
Doctoral Committee Chair(s)
Moore, Jeffrey S.
Committee Member(s)
  • Fout, Alison R.
  • van der Donk, Wilfred A.
  • Mirica, Liviu M.
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
organic synthesis, carbene chemistry, iron catalysis, frontal polymerization, photoredox, ring opening metathesis
Abstract
Metal alkylidenes are versatile synthetic intermediates which have revolutionized multiple chemical fields. They have been used in the synthesis of countless natural products, drugs, and polymers and have contributed to a different understanding of the chemistry of carbon. This thesis deals with two very different applications of this intermediate. The development of an iron catalyzed metallocarbene C—H insertion method is the subject of the first two chapters. Investigation of a photoinitiated frontal ring opening metathesis polymerization method comprises the last two chapters. Iron metallocarbenes are common intermediates in a wide range of synthetic methods, especially cyclopropanation and insertion into heteroatom-hydrogen bonds. Until 2016, there were no catalytic examples of catalytic iron-carbene C—H insertion. The few stoichiometric examples that existed shed some light on the possible kinetic barriers to developing a catalytic version of this protocol. We optimized an iron (III) phthalocyanine method by enhancing the electrophilicity of the metallocarbene intermediate. This method proved effective for a variety of benzylic C—H bonds, including the benzylic position of δ-tocopherol. Mechanistic investigations demonstrated that the C—H insertion mechanism is stepwise. Activity for tertiary C—H bonds was extensively investigated but proved elusive. Frontal polymerization is a method of polymerizing a resin not by heating the entire mixture, but by heating a small amount, which triggers an autoaccelerated polymerization that travels throughout the resin as a wave, or front. A less common initiation method of frontal polymerization is with light. There are only a handful of photoinitated frontal ring opening metathesis polymerization protocols reported. We have developed a photoinitiated, thermally propagated method with a less active bis(N-heterocyclic carbene) catalyst which we hoped would extend storage lifetime from conventional Grubbs second generation catalyzed systems. We did see a marked increase in storage lifetime when the components were split into two separate solutions and these were thoroughly mixed just before ignition. We established some of the materials properties of the resulting polymer and investigated how the frontal polymerization responded to changes in conditions.
Graduation Semester
2021-08
Type of Resource
Thesis
Handle URL
https://hdl.handle.net/2142/117883
Copyright and License Information
Copyright 2021 Chloe Wendell

Owning Collections

Graduate Dissertations and Theses at Illinois PRIMARY
Graduate Theses and Dissertations at Illinois