Arene-Selective Asymmetric Buchner Dearomatization of Biaryl Compounds

We report arene-, stereo-, and regioselective functionalizations of biaryl compounds (A-A') with α-cyanodiazoacetates via Rh(II)-catalyzed enantioselective Buchner dearomatization. Density functional theory calculations suggest that selectivity for ring A' of A-A' biaryl and regioselectivity on arene A' are both determined by steric effects, resulting in high constitutional isomer selectivity among the ≤12 possible. Electron-withdrawing and -donating groups on ring A retain high site selectivity, despite the latter activating ring A toward electrophilic Rh(II)-carbenoid.