Desymmetrization of meso-Cyclopentanones

Significance

Jørgensen and co-workers have achieved the asymmetric desymmetrizing fragmentation of meso-cyclopropane cyclopentanone (1) and epoxide-allylic alcohol rearrangements of meso-epoxy cyclopentanone (3) in the presence of thiourea-modified cinchona alkaloid derivatives (catalyst A or B) via an E1cb-like mechanism. The concept was exploited in asymmetric one-pot and tandem desymmetrizing epoxide-allylic alcohol rearrangement-Michael addition sequences of epoxycyclopentanone (3, R = H) by performing the reaction in the presence of thiol and malonate nucleophiles or prior to a rhodium-catalyzed vinylation. A kinetic resolution of 5 by means of this method is also presented.