Y. Morisaki et al., A new route to cyclopentenones via ruthenium-catalyzed carbonylative cyclization of allylic carbonates with alkenes, ORG LETT, 2(7), 2000, pp. 949-952
[GRAPHICS]
[RuCl2(CO)(3)](2)/Et3N (eta(3)-C3H5)RuBr(CO)(3)/Et3N are highly effective c
atalyst systems for carbonylative cyclization of allylic carbonates with al
kenes to give the corresponding cyclopentenones in high yields. For example
, treatment of allyl methyl carbonate (1a) with 2-norbornene (2a) in the pr
esence of a catalytic amount of [RUCl2(CO)(3)](2) (2.5 mol %) and Et3N (10
mol %) at 120 degrees C for 5 h under 3 atm of carbon monoxide gave the cor
responding cyclopentenone, exo-4-methyltricyclo[5.2.1.0(2,6)]dec-4-en-3-one
(3a), in 80% yield with high stereoselectivity (exo 100%).