Reactions of Homogeneous Gold Catalysis: Ligand Design, Alkynes, and Gold-Carbenes
- Author(s): Nelson, Jonathan David
- Advisor(s): Zhang, Liming
- et al.
The last decade has seen a rapid rise in the developments in homogeneous gold catalysis. The soft Lewis acidity of cationic gold(I) complexes towards alkynes and allenes and the easy access to gold carbene intermediates via oxidation have produced a diverse range of synthetically versatile transformations. In my thesis, several novel methodologies have been explored and developed, including: (1) The design of novel new ligands to enable highly efficient gold-catalyzed nucleophilic addition reactions, including the development of P,S-bidentate ligands, which enabled the generation of tris-coordinated gold carbene species, and provided high selectivity and yields for propargylic ether to undergo a 1,2-C–H insertion; (2) The highly regioselective oxidation of carboxylates of primary and secondary propargylic alcohols, undergoing 1,2-acyloxy migrations over a 1,2-C–H migration, with selectivity was greatly enhanced by using the P,S-bidentate ligand, with ratios ranging from 16 to over 300; (3) An investigation into the effects of α-oxo gold-carbene electrophilicity on product selectivity of propargylic ethers to undergo 1,2-alkyl-migration versus 1,2-C–H insertion, along with the application of said 1,2-alkyl migration to both ring expansion and the migration of a propargylic sp2 substituents; excellent regioselectivities were obtained for the gold catalyzed oxidation of propargylic ethers while selecting for the hydride migration.