Catalytic Enantioselective Oxaziridination

Significance

Jørgensen and colleagues disclose a catalytic asymmetric synthesis of oxaziridines 3 via the oxidation of aldimines 1 with MCPBA. Cinchona alkaloid derivative 2, which features a hydrogen-bonding site (phenolic group) and a Brønsted basic moiety (quinuclidine nitrogen) proved to be the optimal catalyst. A variety of electron-neutral and electron-poor aryl aldimines as well as alkyl aldimines underwent the oxaziridination with good to excellent yields and enantio­selectivities. Kinetic studies indicated a pseudo-first order for both MCPBA and the aldimine, supporting the catalyst-substrate assembly model shown above. Competition experiments further indicated a stepwise mechanism.