AbstractIn Chapters 2 and 3 Ir(I)-catalysed methodology for the asymmetric hydroarylation of terminal alkenes is described. Initially an extensive screen of commercially available ligands was conducted to render a branch-selective alkene hydroarylation protocol previously developed at Bristol enantioselective. This study revealed ligand related reactivity trends, which enabled Dr. Simon Grélaud to design and synthesise a family of chiral bisphosphite ligands that promote highly enantioselective alkene hydroarylation with acetanilide substrates. Alongside Dr. Simon Grélaud, the protocol was expanded to thiophene substrates. Subsequently, investigations were directed towards the
enantioselective alkylation of alternative heteroaromatic substrates. Excellent yields and highly promising levels of enantioselectivity have been achieved for styrene hydroarylation with pyrrole and furan moieties.
In Chapter 4 the scope of the Ir(I)-catalysed methodology is expanded to include 1,1-disubstituted alkenes. Challenging all-carbon quaternary centres have been generated in excellent yields and studies towards an enantioselective protocol have been undertaken. The mechanistic pathway has been investigated through deuterium labelling experiments and natural abundance 13C KIE studies using
the Singleton method. These results revealed a pathway unique to those previously determined at Bristol for Ir(I)-catalysed hydroarylation of mono-substituted alkenes.
In Chapter 5 an Ir(I)-catalysed method is presented for the a-selective C−H arylation of styrenes by dual C−H functionalisation. The chemistry relies upon an Ir(I)-catalyst modified with an electrondeficient ferrocene-based bisphosphine ligand. This reaction offers a regioisomeric alternative to the Pd-catalysed Heck and Fujiwara-Moritani reactions. The alkenylated products are useful moieties to
rapidly build interesting N-containing heteroaromatics.
|Date of Award||23 Jan 2020|
|Supervisor||John Bower (Supervisor)|