Synthesis Of D-Camphor Based N,P-ligands And Their Application In Asymmetric Allylation

Allylic alkylation reaction is one of the most important organic reactions in organic synthesis. The reaction was applied successfully in the construction of various functional compounds, such as C-H, C-C, C-O, C-N, C-S, and other carbon-heteroatoms bond-forming approaches. The design and synthesis of the novel multifunctional phosphine ligands is one of the most important topics in allylic alkylation reaction. In this thesis, we have synthesized a series of D-camphor-based chiral N,P-ligands, and studied the application of these ligands in Allylic alkylation reaction.Here we report a modularly synthetic strategy to D-camphor-based chiral N,P-ligands on the basis of previous findings in Schiff base and chiral ligand chemistry. Commercially available D-camphor is extremely attractive for the development of effective phosphine ligands because of multiple stereogenic centers on the camphor backbone and the rigid structure as well as the reactive ketone moiety. The chiral N,P-ligands were easily synthesized and stabilized in the air. Finally, the effectiveness of this new Schiff base with chirality matching as a bidentate chelating N,P-ligand is demonstrated in the palladium-catalyzed allylic alkylation with various nucleophiles. The research shows that, a family of new Schiff base derived from chiral D-camphor has been determined as an effective phosphine ligand for the asymmetric palladium-catalysed allylic alkylation of activated methylene compounds, allylic amination of primary amines and secondary amines, and allylic etherification of alcohols, in which the corresponding products with various functional groups were achieved in good yields(98%) and excellent enantioselectivities (up to>99%ee). Remarkably, it was showed the Schiff base L2-derived palladium catalyst system afforded the highest level of enantioselectivity in the related allylic alkylation, reported to date, which revealed the privileged role of D-camphor-derived Schiff base in the palladium catalysis.