The development of Pd(II)-catalysed oxidative Heck reactions and C-H functionalisations

Abstract

This thesis outlines the work undertaken on three projects focusing on the development of Pd(II)-catalysed oxidative Heck reactions and C-H functionalisations. Chapter one reviews literature related to palladium catalysis, specifically the oxidative Heck reaction, its development and the most recent advances in this area. Chapter two describes methodology developed to switch the outcome of the ligand- and base-free Pd(II)-catalysed reaction between cyclic enones and boronic acids from conjugate addition to oxidative Heck product, by simply changing the solvent. Additionally, factors which favour one reaction over the other are also discussed. Chapter three outlines the successful development of a palladium-catalysed direct C-H functionalisation of benzoquinone. Both mono and difunctionalisations can be carried out selectively in excellent yields and a wide variety of functional groups are tolerated. Regioselectivity of the difunctionalisation reactions appears to be determined by the electronic properties of the boronic acid used. A successful one-pot procedure for the heterodifunctionalisation of benzoquinone is also outlined. Chapter four details the development of oxidative Heck reactions on challenging 2,2-disubstituted cyclopentene-1,3-dione substrates with aryl boronic acids. An efficient enantioselective protocol provides a facile way to desymmetrise the all carbon quaternary stereocentre present in the cyclopentenedione substrates and includes the synthesis of (+)-preussidone.