Rhodium(I)-Catalyzed Enantioselective Activation of Cyclobutanols: Formation of Cyclohexane Derivatives with Quaternary Stereogenic Centers

The activation of carbon-carbon σ bonds is a complementary method to access uncommon and difficult-to-prep. organometallic species. Herein, we describe the activation of tert-cyclobutanols through an enantioselective insertion of a chiral rhodium(I) complex into the C-C σ bond of the cyclobutane, forming a quaternary stereogenic center and an alkyl-rhodium functionality that initiates ring-closure reactions. This technol. provides access to a variety of substituted cyclohexane derivs. with quaternary stereogenic centers. The formation of different product families can be controlled by the employed set of reaction conditions and additives. In general, high yields and excellent enantioselectivities of up to 99 % ee are obtained.