Harnessing triaryloxonium ions for aryne generation and stereogenic control of oxygen

Thesis

Oxonium ions are perceived to be highly reactive electrophiles, thus, triaryloxonium ions have been underutilised in synthesis despite their remarkable stability. This body of work explores novel applications of triaryloxonium ions. Chapter 1 demonstrates their utility as benzyne precursors, activated with weak bases to achieve broad functional group tolerance, offering a complementary approach to alternative aryne-generating methods. This is further illustrated by their compatibility with a diverse range of arynophiles.

Inspired by these findings, Chapter 2 assesses their potential application as hetaryne precursors. Synthetic routes towards heteroaromatic-containing triaryloxonium ions as well as methods to enhance their stability are evaluated. Various heteroaromatic triaryloxonium ions exhibit aryne-like reactivity in the presence of base and arynophiles, including the five-membered hetaryne, 2,3-benzothiophyne.

Beyond aryne generation, the Smith group has harnessed triaryloxonium ions to generate the first chiral, non-racemic, and configurationally stable molecule in which the oxygen atom is the sole stereogenic centre. This work probes the configurational stability of this oxonium ion by conducting kinetic analysis of the enantioenriched oxonium to measure the inversion barrier of the stereogenic oxygen centre.

Authors: Hindson, M

• DOI: 10.5287/ora-pr5mdxv79
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: triaryloxonium; oxonium; hetaryne; aryne
• Subjects: Organic compounds--Synthesis