Asymmetric Benzoylation of meso-Hydrobenzoin Using a Reusable Tripodal Imidazoline–Pyridine–Cu Catalyst

Abstract

Chiral, self-supported, polytopic imidazoline–pyridine ligands were designed and synthesized for use in Cu catalysis. The tripodal imidazoline–pyridine L6-Cu(BF₄)₂ complex catalyzed the asymmetric p-(tert-butyl)benzoylation of meso-hydrobenzoin to give the adduct in up to 85 % ee. After completion of the asymmetric benzoylation reaction, the self-supported tripodal imidazoline–pyridine–Cu catalyst could be easily recovered as a precipitate by adding hexane, and the recovered catalyst could be reused several times while maintaining the catalyst activity and selectivity.