Asymmetric Synthesis of Functionalized Cyclopentanones via a Multicatalytic Secondary Amine/N-Heterocyclic Carbene Catalyzed Cascade Sequence

A one-pot, asymmetric multicatalytic formal [3+2] reaction between 1,3-dicarbonyls and alpha,beta-unsaturated aldehydes is described. The multicatalytic process involves a secondary amine catalyzed Michael addition followed by a N-heterocyclic carbene catalyzed intramolecular crossed benzoin reaction to afford densely functionalized cyclopentanones with high enantioselectivities. The reaction proceeds with a variety of alkyl and aryl enals as well as a range of 1,3-dicarbonyls (diketones and beta-ketoesters). The functionalized products are obtained from cheap, readily available starting materials in a rapid and efficient manner in a one-pot, one-step operation.