Uranium(IV) BINOLate Heterobimetallics: Synthesis and Reactivity in an Asymmetric Diels-Alder Reaction

The first heterobimetallic BINOLate complexes incorporating uranium were prepared, and their reactivity in an asymmetric Diels-Alder reaction was investigated. The contributions of both the Li+ and U-IV cations to the reaction selectivity were addressed through control of the two different Lewis acidic centers. The presence of an anionic ligand in the seventh coordination site of the central uranium cation resulted in enhanced selectivity compared to the RE(III) catalyst with the same alkali metal cation and represents the highest enantioselectivities obtained with a uranium-based catalyst to date. Additionally, we describe a simple workup procedure to obtain organic products free of the trace radioactivity present in the reaction mixtures.