Rhodium(I)-catalyzed cycloisomerization of alkene-substituted allenylcyclopropanes: stereoselective formation of bicyclo[4.3.0]nonadienes.

A productive channel for pent-up energy: The [{RhCl(CO)2 }2 ]-catalyzed ring-opening of both E and Z 1-cyclopropylocta-1,2,6-trienes exclusively produced cis-4,5-dimethylbicyclo[4.3.0]nona-1(9),2-dienes with three contiguous stereogenic centers. When this transformation was applied to the 1,2,7-triene double-bond isomers, the same products were formed in a completely stereoselective manner.