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Unique Reactivity Patterns Catalyzed by Internal Lewis Acid Assisted Hydrogen Bond Donors

Auvil, Tyler Jay
http://rave.ohiolink.edu/etdc/view?acc_num=osu1395759920

Abstract Details

2014, Doctor of Philosophy, Ohio State University, Chemistry.
The advancement of hydrogen bond donor (HBD) organocatalysis has been inhibited by a number of challenges. Conventional HBDs suffer from high catalyst loadings and operate in only limited types of reactions, typically the activation of 1,2- and 1,4-acceptors for nucleophilic attack. One strategy to address the shortcomings of HBD catalysis is to design innovative catalysts with improved reactivity. To this end, boronate ureas have been developed as a new family of enhanced HBD catalysts that enable useful new reactivity patterns. Boronate ureas are easily-accessible, small organic molecules that benefit from improved catalytic abilities plausibly due to internal coordination of the urea carbonyl to a strategically placed Lewis acid. Optimization of the boronate urea scaffold has revealed their enhanced catalytic activity, enabling new directions in HBD catalysis. The discovery of boronate ureas has allowed for the unveiling of new HBD activation modes, providing unique reactivity patterns that are inaccessible with conventional HBD catalysts. Among these reactivity patterns is the activation of strained nitrocyclopropane carboxylates for nucleophilic ring-opening reactions, which affords a swift route to access gamma-amino-alpha-nitroester building blocks. The ring-opening method was highlighted by its utilization in the total synthesis of a CB-1 receptor inverse agonist, which was recently patented by Eli Lilly. Additionally, boronate ureas can elicit carbene-like reactivity from alpha-diazocarbonyl compounds, allowing for organocatalytic heteroatom-hydrogen insertions reactions, the first of their kind. The boronate urea activation of alpha-nitrodiazoesters has permitted the development of an unsymmetric double alpha-arylation process, affording a synthetically challenging motif in a single flask. The alpha-arylation reaction proceeds through a conceptually novel organocatalytic transient N-H insertion process, employing anilines as carbene activators. The use of boronate urea catalyst have also allowed for heteroatom-hydrogen insertion reactions by alpha-aryldiazoacetates. These reactions are proposed to occur through a HBD induced heteroatom acidity amplification, facilitating protonation of the alpha-aryldiazoacetates. Herein, the catalyst design and the road to discovery of these new reactivity patterns are discussed.
Anita Mattson (Advisor)
Jon Parquette (Committee Member)
Psaras McGrier (Committee Member)
290 p.
Chemistry
Boronate Urea; Hydrogen Bond Donor Catalyst; Organocatalyst; Internal Lewis Acid; Insertion; Nitrocyclopropane Carboxylate; Diazo Compound

Recommended Citations

Citations

  • Auvil, T. J. (2014). Unique Reactivity Patterns Catalyzed by Internal Lewis Acid Assisted Hydrogen Bond Donors [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1395759920

    APA Style (7th edition)

  • Auvil, Tyler. Unique Reactivity Patterns Catalyzed by Internal Lewis Acid Assisted Hydrogen Bond Donors. 2014. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1395759920.

    MLA Style (8th edition)

  • Auvil, Tyler. "Unique Reactivity Patterns Catalyzed by Internal Lewis Acid Assisted Hydrogen Bond Donors." Doctoral dissertation, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1395759920

    Chicago Manual of Style (17th edition)

osu1395759920
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This open access ETD is published by The Ohio State University and OhioLINK.