Enantioselective Organocatalytic Michael Addition of Cyclobutanones to Nitroalkenes

Synthetic applications of cyclobutanones other than ring expansion and fragmentation reactions are rare. Herein, highly efficient diastereo- and enantioselective organocatalytic Michael additions of 2-substituted cyclobutanone derivatives to nitroalkenes are reported allowing the stereocontrolled creation of all-carbon quaternary centers. The approach relies on both the use of Bronsted base/hydrogen-bond donor bifunctional organocatalysts, and importantly, the specific stabilization and activation of cyclobutanone with a secondary amide moiety. The reaction was found to nicely accommodate a broad scope of substrates, allowing the control of up to three contiguous stereogenic centers. This work has opened new synthetic opportunities.