Exploration of a new face of catalysts in general C-C and C-N bond-construction processes

Abstract

Palladium-catalyzed amination is a powerful tool for synthesizing nitrogen containing compounds in material science, pharmaceuticals as well as organic synthesis. Our research group reported a palladium-catalyzed amination of aryl mesylate in 2008. The substrate scope expanding to aryl tosylates has been attempted. An efficient method for synthesis of amines via palladium-catalyzed amination of aryl tosylates with amines is hereby reported. The investigations on the effect of solvents and bases in palladium catalyzed amination of aryl tosylate will be described and the experimental results on substrate scopes will be discussed. Current study shows that a great diversity of aryl tosylates and amines can be used for C-N bond formation. The reaction conditions are not only restricted to the organic solvents used, solvent-free conditions and aqueous medium can also be accomplished. Good to excellent yields of the desired products can be achieved. The next part of my research study is the development of a new class of phosphine ligand for general carbon-carbon and carbon-nitrogen bond formation reactions. The preliminary results showed that the phenyl imidazolidinyl backbone ligands were less effective for catalytic reaction. Thus, we modified the ligand scaffold to phenyl benzimidazolyl backbone. It can be easily synthesized from inexpensive and commercial available materials. Hemilabile phenyl benzimidazolyl ligand is an effective ligand for catalytic synthesis. The scope of aryl chlorides and amines via palladium-catalyzed amination utilizing benzimidazolyl ligand is described. Primary and secondary aromatic/aliphatic amines are effective substrates in this catalytic system. Functional group such as keto and esters are also compatible in this system. Good to excellent yields of the desired products can be achieved. Catalyst loading down to 0.1 mol% Pd can also be accomplished.