Enhancing the Borylation Experience: Strategies for Heteroaromatic Borylation

Iridium-catalyzed C-H borylation is an attractive method for synthesis of heteroaromatic boronate esters. Disappointingly however, the Lewis-basicity of azinyl heterocycles limits their application in this methodology due to coordination to the iridium catalyst. Furthermore, the propensity for certain heteroaromatic boronate esters to undergo protodeborylation limits their application in downstream or one-pot chemistries. The work undertaken towards this thesis enables these effects to be tempered thus widening the substrate scope of C-H borylation. Chapter 1 discusses the various routes to boronic acids and their derivatives, as well as their use in functional group transformations and bond forming reactions. Chapter 2 explores the background, mechanism and substrate scope of C-H borylation and looks at its application to the functionalisation of typically stubborn heterocycles. Chapter 3 applies the findings and strategies developed in Chapter 2 to a focussed case study on the borylation of indazole and its derivatives. Chapter 4 discusses the work undertaken towards the development of a one-pot single-solvent C-H borylation/oxidative Heck-coupling protocol.