Enantioselective Assembly of Congested Cyclopropanes using Redox-Active Aryldiazoacetates

The enantioselective assembly of quaternary stereocenters through sequential functionalization of versatile carbon-atom precursors has the potential to systematize the synthesis of these ubiquitous stereogenic elements. Herein, we report two catalytic processes that allow the realization of this concept in the enantioselective synthesis of cyclopropanes. We demonstrate that C-H functionalization, carbene-transfer, and decarboxylative cross-coupling can sequentially take place in the same carbon atom to obtain highly enantioenriched cyclopropane products. The reactions reported herein give access to redox-active analogues of privileged aryldiazoacetates and demonstrate their enantioselective carbene transfer with a simple and practical rhodium catalyst.