Chiral tetra-coordinate aluminum cation in catalysis

Although the application of cationic aluminum complexes in catalysis has been extensively investigated, the incorporation of an aluminum cation into a chiral environment is less explored. In this study, a C2-symmetric chiral tetra-coordinate aluminum cation [3]+ bearing two chiral amino alcohol-derived ligands was prepared from commercially available starting materials in two steps. The high Lewis acidity of [3]+ exceeding that of B(C6F5)3 was verified by a competition binding experiment. Preliminary catalytic activity studies of [3]+ revealed that the tetra-coordinate aluminum cation is effective in accomplishing high conversion in all cases. However, the presence of a labile N?Al bond diminishes the enantioselectivity of the activation process. ? 2021 American Chemical Society