The development of palladium(II)-catalysed auto-tandem and desymmetrisation reactions

Abstract

This thesis outlines the work undertaken by the author on two projects, focusing on the development of Pd(II)-catalysed desymmetrisation coupling reactions. Chapter one reviews literature pertaining to Pd(II)-catalysed coupling reactions, more specifically the oxidative Heck coupling reaction, its initial development and advancement. The related Pd(II)-catalysed conjugate addition reaction is also briefly discussed. Chapter two describes the successful development of a Pd(II)-catalysed auto-tandem reaction, where the same Pd(II)-catalyst was utilised for both a dehydrogenation reaction and an oxidative Heck coupling reaction in one-pot. 2,2-Disubstituted cyclopentanediones were first dehydrogenated to the corresponding enedione before an oxidative Heck desymmetrisation reaction. The racemic reaction was investigated in both batch and continuous flow, as well as a batch and telescoped approach for the enantioselective reaction. Chapter three outlines the pursuit to desymmetrise more complex meso-cyclic systems, which contain up to five-contiguous stereocentres, utilising Pd(II)-catalysis. An efficient protocol was developed to desymmetrise meso-polycyclic cyclohexenediones under mild Pd(II)-catalysed conditions in good yields and excellent enantiomeric ratios.