Cobalt-Catalyzed Dual Construction of peri-(C–C) and (C–N)/(N–N) Atropisomerism via C–H Activation

Axially chiral biaryls bearing an atropisomeric C–C axis at peri-substituted positions are difficult to access, and this difficulty compounds when the same scaffold must also carry a second, independent C–N or N–N axis, a combination that remains largely unexplored. Here we report an efficient, cost-effective route to these dual-axial atropisomers through enantioselective Co(II)/Salox-catalyzed C–H/N–H annulation. Arylbenzamide substrates bearing two distinct classes of directing groups react with peri-substituted alkynes to install both stereogenic axes in a single step. The reaction tolerates a broad range of substituents, proceeds in good yield, and delivers excellent stereocontrol (up to >99% ee, >20:1 dr). Mechanistic studies, supported by density functional theory (DFT) calculations, clarify the origin of the observed stereoselectivity. The resulting dual-axial atropisomers are fluorescent, and their photophysical properties point to potential applications in optoelectronic materials.