A General Synthetic Route to Differentially Functionalized Angularly and Linearly Fused [6−7−5] Ring Systems: A Rh(I)-Catalyzed Cyclocarbonylation Reaction

Investigations of a Rh(I)-catalyzed cyclocarbonylation reaction reveal its general synthetic utility for accessing highly functionalized tricyclic [6−7−5] linear and angular ring systems from allene−ynes. Three types of allene−ynes were prepared and subjected to Rh(I)-catalyzed cyclocarbonylation conditions. For three series of allene−ynes, the [6−7−5] ring systems were afforded in varying yields depending on the substrate structure. One series of allene−ynes afforded the [6−6−5] ring system possessing an α-alkylidene cyclopentenone as a result of a selective reaction with the proximal double bond of the allene.