Advances in Palladium-Catalyzed Conjunctive Cross-Coupling

Abstract

The development of boron and palladium ligands for conjunctive cross-coupling provides access to new reactivity. Some of these advances are outlined in this dissertation. Chapter one describes an enantioselective and diastereoselective palladium catalyzed conjunctive cross-coupling of β-substituted alkenyl boron “ate” complexes to afford contiguous benzylic stereocenters. “Mac” diol was discovered as a useful boron ligand in conjunctive cross-coupling by reducing unwanted Suzuki-Miyaura cross-coupling. Chapter two describes the utilization of “mac” diol in the enantioselective conjunctive cross-coupling of α-substituted alkenyl boron “ate” complexes with carbamoyl chlorides. This transformation affords tertiary, β-boryl amides, which provide a complementary approach to Mannich, aldol, and conjugate borylation products. Water was an essential additive to enable high yield and high enantioselectivity, and its reaction role was investigated. The synthetic utility of this cross-coupling was demonstrated with the asymmetric synthesis of (+)-adalinine. Chapter three describes the thought process behind discovering a new palladium ligand for conjunctive cross-coupling. Phosphinooxazolines (PHOX) are useful and inexpensive ligands for enantioselective palladium-catalyzed conjunctive cross-coupling. A stereochemical model of this cross-coupling with this ligand was examined.