Highly Enantioselective Rhodium(I)-Catalyzed Activation of Enantiotopic Cyclobutanone C-C Bonds

The selective functionalization of carbon-carbon sigma bonds is a synthetic strategy that offers uncommon retrosynthetic disconnections. Despite progress in CC activation and its great importance, the development of asymmetric reactions lags behind. Rhodium(I)-catalyzed selective oxidative additions into enantiotopic CC bonds in cyclobutanones are reported. Even operating at a reaction temperature of 130 degrees C, the process is characterized by outstanding enantioselectivity with the e.r. generally greater than 99.5:0.5. The intermediate rhodacycle is shown to react with a wide variety of tethered olefins to deliver complex bicyclic ketones in high yields.