The Ru3(CO)12-Catalyzed Intermolecular [2 + 2 + 1] Cyclocoupling of Imines, Alkenes or Alkynes, and Carbon Monoxide: A New Synthesis of Functionalized γ-Lactams
The reaction of imines which contain N-heterocycles or an ester group with alkenes or alkynes and carbon monoxide in the presence of a catalytic amount of a ruthenium carbonyl results in [2 + 2 + 1] cyclocoupling to give γ-butyrolactams in good yields.
1-(4-Methoxypheny])azetidin-2-ones 5a–5g were acetoxylated by lead(IV) acetate to afford the corresponding compounds 6a, 6b, 6c' and 6d–6g. In the d series elimination products 9 and 10 were also formed. Ring homologue 7a afforded the hydrotylated derivative 8'a.