(±)-Lupinine and (±)-epilupinine have been prepared starting from commercially available 6-valerolactam. The synthetic route involves the advantages of the cyclization based on α-sulfinyl carbanions.
The intramolecular nucleophilic addition of α-sulfinyl carbanions derived from the corresponding sulfinyl lactams afforded 1-azabicyclo[m.n.0]alkenes in good yields.