Generality-oriented optimization of enantioselective aminoxyl radical catalysis.

Catalytic enantioselective methods that are generally applicable to a broad range of substrates are rare. We report a strategy for the oxidative desymmetrization of meso-diols predicated on a nontraditional catalyst optimization protocol by using a panel of screening substrates rather than a singular model substrate. Critical to this approach was rational modulation of a peptide sequence in the catalyst incorporating a distinct aminoxyl-based active residue. A general catalyst emerged, providing high selectivity in the delivery of enantioenriched lactones across a broad range of diols, while also achieving up to ~100,000 turnovers.

Copper-Catalyzed Asymmetric Reductions of Aryl/Heteroaryl Ketones under Mild Aqueous Micellar Conditions.

Enantioselective syntheses of nonracemic secondary alcohols have been achieved in an aqueous micellar medium via copper-catalyzed (Cu(OAc)2·H2O/(R)-3,4,5-MeO-MeO-BIPHEP) reduction of aryl/heteroaryl ketones. This methodology serves as a green protocol to access enantio-enriched alcohols under mild conditions (0-22 °C) using a base metal catalyst, together with an inexpensive, innocuous, and convenient stoichiometric hydride source (PMHS). The secondary alcohol products are formed in good to excellent yields with ee values greater than 90%.