Toward the synthesis of azido-crown ethers with unusual nitrene reactivity

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Authors
Williams, Megan E.
Advisor
Poole, James S.
Issue Date
2011-07-23
Keyword
Degree
Thesis (M.S.)
Department
Department of Chemistry
Other Identifiers
Abstract

It has been shown that photolysis of 4-azidopyridine N-oxide yields the singlet nitrene, which undergoes intersystem crossing at room temperature to generate triplet 4- nitrenopyridine N-oxide. The room temperature photochemistry is dominated by triplet nitrene chemistry leading to the formation of the azo-dimer. This unusual behavior is a result of selective stabilization of the lowest singlet state of the nitrene by the N-oxide group. In this study, we wish to investigate the effect of complexation of the N-oxide group with a metal cation on the kinetics and reactivity of 4-nitrenopyridine N-oxide and related compounds. It is envisaged that complexation will alter the polarity of the N-oxide bond making it less capable of spin delocalization in the nitrene. Complexation may be achieved through two different methods: complexation with cations in aqueous salt solutions and complexation of cations inside crown ethers. Crown ethers provide useful models due to the selectivity of complexation with different ions based on ring size and slower diffusion of cations away from the N-oxide group. Progress toward the multi-step synthesis of crown ethers containing the 4- azidopyridine N-oxide substructure is described herein.

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