Synthetic Methods Based on Organophosphorus Redox Cycling
Open Access
- Author:
- Reichl, Kyle David
- Graduate Program:
- Chemistry
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- January 28, 2016
- Committee Members:
- Alexander Thomas Radosevich, Dissertation Advisor/Co-Advisor
Prof Kenneth Feldman, Committee Member
RAYMOND LEE FUNK, Committee Member
Michael John Janik, Committee Member - Keywords:
- synthetic methods
redox cycling
phosphorus
pyramidal inversion
regioselective allylic reduction
enediyne - Abstract:
- Tricoordinate organophosphorus compounds are commonly utilized as two-electron donors in synthetic chemistry, figuring prominently as nucleophilic catalysts and spectator ligands for transition metal complexes. Apart from this Lewis basic role, phosphines also engage in redox chemistries, acting primarily as stoichiometric O-atom acceptors for classical P(III)/P(V)=O processes such as the Wittig reaction. Recent advances have begun to render many of these transformations catalytic in phosphorus, demonstrating the capacity of phosphines to behave as competent main group redox catalysts. Yet despite the significant progress in this area, applying the redox-active nature of organophosphorus compounds towards non-deoxygenative organic synthesis remains a substantial challenge. This dissertation seeks to address this potentially impactful challenge, and therefore describes the development of several non-oxo P(III)/P(III+n) (n = 1, 2) redox processes. Specifically, Chapter 2 details the reversible single electron oxidation of P-stereogenic phosphines, and the ensuing consequences with respect to structural/stereochemical integrity. Chapters 3 and 4 concern a novel phosphorus-catalyzed regioselective reduction of allylic bromides, and the critical role of strained phosphacycles on the P(III)/P(V) redox cycle. Chapter 5 further demonstrates the impact of organophosphorus structure on reactivity, allowing for the divergent reactivity of ethynylphosphonium cations. Taken together, these individual processes provide further insight into the fundamental impacts of both oxidation state and structural perturbations on the reactivity of organophosphorus compounds, and develop a framework with which to further expand redox-active organophosphorus processes.