Asymmetric Catalytic Hydroamination: New Ligand Synthesis
Mentor:Adam Johnson, Professor of Chemistry, Harvey Mudd College
Hydroamination is a highly atom economical method for synthesizing a nitrogen containing group. Although Hydroamination is thermoneutral, the reaction requires a catalyst due to the electronic repulsion between the nitrogen and the unsaturated group. Recent studies have involved investigating multiple types of substituted metal catalysts using tantalum or titanium as the central metal to acquire 80 percent enantiomeric excess (e.e.) as the highest selectivity. To further understand the relationship between the size of the ligands and the selectivity of the reaction, our studies focused efforts on developing new catalysts with even bigger and chiral ligands attached on them. In this study, primarily Grignard and direct reductive amination methods were used to synthesize different ligands. Column chromatography and recrystallization were used to purify the products, and NMR and GCMS were used to determine the structure of the products obtained by the reactions. The results show that two ligands were successively made with obtaining 50% e.e. as the highest selectivity for one of the ligands. Since this new ligand had the third highest selectivity compared to others previously made, the results seem to suggest a possible relevance between the size of the ligands and the selectivity of the reaction.