Iridium-Catalysed Borylation of Heteroaromatic C-H Bonds

Abstract

Organoboron compounds are of great importance to organic, medicinal, and materials chemistry, representing key intermediates for the introduction of a wide variety of functional groups. This is best exemplified by the Suzuki-Miyaura cross-coupling reaction. In recent years, the direct C-H borylation of arenes has become an attractive method for the synthesis of aryl boronate esters. However, this transformation is more challenging for heteroarenes bearing an azinyl nitrogen atom, where the presence of the nitrogen lone pair can inhibit the reaction. This is particularly evident at the proximal C-H bond, where C-H activation often does not occur. Whilst many heteroarenes have been investigated, aminopyrazoles remain underexplored. This nucleus features in an array of bioactive molecules, such as herbicides, anti-cancer, and anti-parastic drugs. This thesis presents simple methods for the selective C-H functionalisation of 3- and 5-aminopyrazoles.