Efficient control of π-alkyne and vinylidene complex pathways for the W(CO)5(L)-catalyzed synthesis of two types of nitrogen-containing bicyclic compounds

When omega-acetylenic dienol silyl ethers containing NMS part in the tether were treated with a catalytic amount of W(CO)(6) under photoirradiation, 2-azabicyclop[3.3.0]octanes were obtained in good yield via pi-alkyne complexes. On the other hand, treatment of the same substrates with a catalytic amount of W(CO)6 in the presence of n-Bu3N under the same reaction conditions gave 3-azabicyclo[3.3.0]octanes in good yield exclusively via vinylidene complexes. Thus, the pi-alkyne and vinylidene complex pathways are easily controlled by using a catalytic amount of W(CO)5(L) and an amine.