Alkali and Alkaline Earth Metal Complexes for Catalytic Hydroaminations

1. Alkali and Alkaline Earth Metal Complexes for Catalytic Hydroaminations Kai C. Hultzsch, Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854-8087 The catalyzed addition of amines to unsaturated carbon-carbon bonds, the so-called hydroamination, represents a waste-free, highly atom-efficient and green pathway for the synthesis of industrially important bulk chemicals, specialty chemicals and pharmaceuticals. While most studies have focused on the development of transition metal-based catalyst systems, our research program primarily aims to develop catalysts that utilize significantly less toxic main group metals. Significant challenges represent the labile metal-ligand interactions of main group metals. In particular facile Schlenk-type ligand redistribution processes can potentially thwart efforts to perform enantioselective transformations. We have now identified a phenoxyamine magnesium catalyst system incorporating a sterically demanding triphenylsilyl substituent that combines good catalytic activity and high thermal stability, which represents an important milestone in our efforts to prepare chiral alkaline-earth metal hydroamination catalysts. In a second approach we are investigating the chemistry and catalytic activity of diamidobinaphthyl dilithium complexes as chiral hydroamination catalysts.The steric demand of the chelating donor group has a significant influence on the structure of these complexes, as indicated by the one-of-a-kind heterochiral cyclic hexameric structure shown on the left. Current investigations focus on the structure and aggregation state of these species in solution and their catalytic performance in asymmetric hydroamination reactions.