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.