An expedient approach to highly enantioenriched cyclic nitrones mediated by robust and recoverable C3-symmetric cinchonine-squaramide catalysts

Abstract

The C₃-symmetric cinchonine-squaramide catalyzed asymmetric Michael addition of β-ketosulfones to nitroalkenes is presented. Subsequent transformation leads to chiral cyclic nitrones with excellent results (up to 85% yield and >99% ee). The catalyst can be recovered and reused for six cycles without losing activity and selectivity.