Enantioselective Baeyer–Villiger Oxidation: Desymmetrization of Meso Cyclic Ketones and Kinetic Resolution of Racemic 2‑Arylcyclohexanones

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.