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Achieving High Stereoselectivity in Ruthenium-Catalyzed Olefin Metathesis Reactions for Organic and Polymer Synthesis

Citation

Ahmed, Tonia Sarah (2018) Achieving High Stereoselectivity in Ruthenium-Catalyzed Olefin Metathesis Reactions for Organic and Polymer Synthesis. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/KCM2-6W92. http://resolver.caltech.edu/CaltechTHESIS:05312018-145533563

Abstract

Transition metal-catalyzed olefin metathesis has emerged as a powerful tool for constructing C−C double bonds. This thesis delineates the development of Ru-based catalysts for the stereoselective formation of olefins and mechanistic studies used to examine how catalyst structure influences selectivity and activity.

Chapter 2 details the synthesis of Z-selective, cyclometalated catalysts bearing nitrite X-ligands. The activity and selectivity of these catalysts were examined in an array of ring-opening metathesis polymerization and cross metathesis reactions. Comparison of these catalysts with their nitrate-bound analogues is described.

Chapter 3 describes the examination of several Z-selective, cyclometalated catalysts in ring-opening metathesis polymerizations. The polymerizations of a variety of norbornene and norbornene derivatives were examined to determine the tacticity and microstructure of the resulting polymer. Computational studies were used to examine the mechanism of the polymerization reactions.

Chapter 4 examines the decomposition of Fischer carbene complexes derived from cyclometalated catalysts. In-depth NMR studies are used to determine the identity of the decomposition product, and the decomposition pathway is examined through computational studies.

Chapter 5 describes the first example of highly E-selective cross metathesis through kinetic control using stereoretentive, Ru-based catalysts bearing dithiolate catalysts. The preparation of additional stereoretentive catalysts is described for increasing catalyst activity while maintaining or increasing selectivity. A model for the observed stereoselectivity is proposed.

Chapter 6 delineates the preparation of a series of fast initiating, stereoretentive catalysts. These catalysts are assessed in an array of cross metathesis reactions, and significantly enhanced activity is observed in E-selective reactions. The examination of the relationships between the structure of a catalyst and its selectivity and activity is described.

Chapter 7 examines the use of stereoretentive catalysts in the synthesis of Z-macrocycles from diene starting materials bearing a Z-olefin and a terminal olefin. Initiation rate studies are conducted to examine the activity of these catalysts compared to previously reported cyclometallated catalysts used in this ring-closing metathesis reaction. The synthesis of twelve- to seventeen-membered rings with high Z-selectivity is described.

Chapter 8 explores the use of fast-initiating, stereoretentive catalysts for synthesizing E-macrocycles. The preparation of diene starting materials containing two E-olefins is described. Using these catalysts, twelve- to eighteen-membered rings are constructed with high E-selectivity.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:olefin metathesis, ruthenium
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Grubbs, Robert H.
Thesis Committee:
  • Agapie, Theodor (chair)
  • Gray, Harry B.
  • Reisman, Sarah E.
  • Grubbs, Robert H.
Defense Date:29 May 2018
Funders:
Funding AgencyGrant Number
National Institutes of HealthGM031332
National Science FoundationCHE-1502616
Office of Naval ResearchN00014-14-1-0650
National Science Foundation (NSF)CHE-1212767
National Science Foundation Graduate Research FellowshipUNSPECIFIED
Record Number:CaltechTHESIS:05312018-145533563
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:05312018-145533563
DOI:10.7907/KCM2-6W92
Related URLs:
URLURL TypeDescription
doi:10.1016/j.poly.2014.06.055DOIArticle adapted for Chapter 2
doi: 10.1021/jacs.5b12277DOIArticle adapted for Chapter 3
doi: 10.1021/acs.orglett.6b00031DOIArticle adapted for Chapter 5
doi: 10.1021/jacs.6b11330DOIArticle adapted for Chapter 6
doi: 10.1002/anie.201704670DOIArticle adapted for Chapter 7
doi: 10.1039/C8SC00435HDOIArticle adapted for Chapter 8
ORCID:
AuthorORCID
Ahmed, Tonia Sarah0000-0001-9407-0250
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10986
Collection:CaltechTHESIS
Deposited By: Tonia Ahmed
Deposited On:12 Jun 2018 00:44
Last Modified:11 Dec 2018 18:11

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