Enantioselective Rhodium-catalyzed C-C Bond Activation of Cyclobutanones
The activation of carbon-carbon bonds has attracted much attention in the past decade. Despite important progress, the development of asymmetric reactions lags behind. For the first time, asymmetric rhodium(I)-catalyzed direct oxidative additions into enantiotopic C-C bonds of cyclobutanones could be realized. Subsequent carboacylation of tethered olefins and carbonyl groups of the generated rhoda(III)cyclopentanone give an efficient access to complex polycyclic scaffolds in high yields. Despite operating at high reaction temperatures, the processes are characterized by outstanding enantioselectivities of generally greater than 99.5:0.5 er.