Synthesis of Vinyl Spirolactones and Lactams by Sequential Cross-Coupling Metathesis, [2 + 2] Photocycloaddition and Cyclobutane Ring-Opening.

Abstract Unsaturated oxoesters and amides have been submitted to cross-coupling metathesis with trimethylallylsilane using Grubbs' catalyst. The resulting allysilanes underwent, under irradiation, intramolecular [2+2] photocycloaddition leading to trimethylsilylmethylcyclobutanes. By treatment with an appropriate Lewis acid, vinyl spiranic lactones and lactams were isolated in good yields.