Asymmetric Rhodium-Catalyzed C–C Activation of Cyclobutanones
[4+1] vs [4+2]: Catalytic Intramolecular Coupling between Cyclobutanones and Trisubstituted Allenes via C–C Activation.
J. Am. Chem. Soc. 2015;
16 December 2015 (online)
C–C activation is an attractive method to functionalize strained four-membered ring systems. Zhou and Dong demonstrate the utility of allenes as a formal vinyl carbenoid in a rhodium-catalyzed asymmetric intramolecular ring expansion of cyclobutanones.
An impressive substrate scope for this C–C activation protocol is demonstrated. Challenging cyclobutanone substrates such as those that are α-substituted also worked for this methodology, albeit with slightly diminished yields.