Enantioselective Baeyer–Villiger Oxidation: Desymmetrization of Meso Cyclic Ketones and Kinetic Resolution of Racemic 2‑Arylcyclohexanones
journal contributionposted on 17.10.2012, 00:00 by Lin Zhou, Xiaohua Liu, Jie Ji, Yuheng Zhang, Xiaolei Hu, Lili Lin, Xiaoming Feng
Catalytic enantioselective Baeyer–Villiger (BV) oxidations of racemic and meso cyclic ketones were achieved in the presence of chiral N,N′-dioxide–ScIII complex catalysts. The BV oxidations of prochiral cyclohexanones and cyclobutanones afforded series of optically active ε- and γ-lactones, respectively, in up to 99% yield and 95% ee. Meanwhile, the kinetic resolution of racemic 2-arylcyclohexanones was also realized via an abnormal BV oxidation. Enantioenriched 3-aryloxepan-2-ones, whose formation is counter to the migratory aptitude, were obtained preferentially. Both the lactones and the unreacted ketones were obtained with high ee values.