Exploring the Chemistry of 3-Substituted 2-Azanorbornyls in Asymmetric Catalysis

This account summarizes our recent achievements in asymmetric catalysis using 3-substituted 2-azanorbornyl based ligands. Using this structural unit in ligand synthesis offers several advantages over the analogous proline chemistry, such as equal availability of both enantiomers and increased rigidity of the catalysts. The reactions so far performed with good results, include the copper-catalyzed allylic acyloxylation, zinc mediated alkylation of imines, the base-catalyzed rearrangement of epoxides, and the ruthenium-catalyzed transfer hydrogenation. Other reactions where the results are less satisfactory are described are the oxazaborolidine catalyzed borane reduction of ketones, and the copper-catalyzed 1,4-addition of alkyl Grignard reagents to α,β-unsaturated ketones. In the last part of the article, some intriguing ring-opening reactions are described, leading to synthetically very interesting structural units such as α-aminoacids and cycloalkyl amines.

asymmetric catalysis - asymmetric synthesis - 2-azanorbornyl - aza-Diels-Alder