Asymmetric domino multicatalysis for the synthesis of 3-substituted phthalides: cinchonine/NHC cooperative system.
It is demonstrated that two organocatalysts, achiral NHC and chiral bifunctional cinchonine, are mutually compatible and operating concurrently and effectively to promote the asymmetric domino oxidation/oxa-Michael addition reaction. This protocol allowed access to both enantiomers of a product by using two natural, inexpensive pseudoenantiomeric cinchona alkaloids, cinchonine and cinchonidine, as well as to phthalides containing a chiral quaternary carbon center in good enantioselectivities.
Department of Chemistry and Research Institute for Natural Sciences, Hanyang University , Seoul 133-791, Korea.
So Won
SW
Youn
Hyoung Sub
HS
Song
Jong Hyub
JH
Park