Chiral sulfoxides
are valuable in the fields of medicinal chemistry
and organic synthesis. A recycle photoreactor utilizing the concept
of deracemization, where a racemate is converted into a pure enantiomer,
is developed and successfully applied in the syntheses of chiral alkyl
aryl sulfoxides. The recycling system consists of rapid photoracemization
using an immobilized photosensitizer and separation of the enantiomers
via chiral high-performance liquid chromatography, and the desired
pure chiral sulfoxides are obtained after 4–6 cycles. The key
to the success of the system is the photoreactor site, wherein the
photosensitizer 2,4,6-triphenylpyrylium is immobilized on the resin
and irradiated (405 nm) to enable the rapid photoracemizations of
the sulfoxides. As the green recycle photoreactor requires no chiral
components, it should be a useful alternative system for application
in producing chiral compounds.