All-Carbon Quaternary Stereocenters α to Azaarenes via Radical-Based Asymmetric Olefin Difunctionalization

A radical-based
asymmetric olefin difunctionalization strategy
for rapidly forging all-carbon quaternary stereocenters α to
diverse azaarenes is reported. Under cooperative photoredox and chiral
Brønsted acid catalysis, cyclopropylamines with α-branched
2-vinylazaarenes can undergo a sequential two-step radical process,
furnishing various valuable chiral azaarene-substituted cyclopentanes.
The use of the rigid and confined C2-symmetric
imidodiphosphoric acid catalysts achieves high enantio- and diastereo-selectivities
for these asymmetric [3 + 2] cycloadditions.