Organocatalytic Activity of N-Heterocyclic Carbenes in the Michael Addition of 1,3-Dicarbonyls: Application to a Stereoselective Spirocyclization Sequence
Résumé
An eco-compatible diversity-oriented synthesis of a-spirolactones and a-spirolactams is described. The overall transformation involves an olefin cross-metathesis followed by an intramolecular organocatalytic Michael-induced spirocyclization. Under microwave irradiation, the Hoveyda- Grubbs precatalyst can be iteratively used as the source of both the metathesis ruthenium-based catalyst, and the spirocyclization N-heterocyclic carbine catalyst.