New cation-mediated enantioselective transformations and catalytic enantioselective photocyclization

Thesis

This thesis describes the development of novel catalytic enantioselective reactions. Chapter 1 describes the development of transformations mediated by chiral ammonium salts. The historical context of enantioselective phase transfer catalysis is provided and the key fundamental advances are detailed. The development of a cation-mediated kinetic resolution of atropisomeric biaryls is described as well as the synthesis and resolution of a range of substituted BINOLs.

The extension of the chiral cation mediated approach to the dearomatization of 2-naphthols by electrophilic amination and of indoles by C3 alkylation is also described. In both cases, good reactivity and moderate enantioselectivity were achieved.

Chapter 2 focuses on the development of a Lewis acid mediated approach to the catalytic enantioselective [6π] photocyclization of acrylanilides. The work is contextualized by a discussion of the previous approaches to enantioselective photochemical reactions covering direct irradiation, triplet energy transfer and photoredox strategies. The elucidation of competing triplet energy transfer and photoredox pathways to the same product is described alongside an account of the design and development of a photocatalyst that engages predominantly in the photoredox pathway. The reaction was tested on a range of substrates to determine the scope and limitations of the method.

Authors: Jones, BA

• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: dearomatisation; atropisomerism; photocyclisation; catalysis; photochemistry; phase transfer catalysis
• Subjects: organic chemistry