Rhodium-Catalyzed Asymmetric Cycloisomerization of 1,6-Ene-ynamides

The rhodium-catalyzed asymmetric cycloisomerization of heteroatom-bridged 1,6-ene-ynamides proceeded to give high yields of functionalized 3-aza- and oxabicyclo[4.1.0]heptene derivatives with high enantioselectivity, which was achieved by use of a rhodium/chiral diene catalyst. The 1,6-ene-ynamides substituted with 2-oxazolidinone and 2-azetidinone moieties at the alkyne terminus were found to display high reactivity towards the rhodium/chiral diene catalyst, where the chelate coordination of the alkyne moiety and the carbonyl oxygen of the ene-ynamides might be responsible for the high catalytic activity.