Enantioselective Cross-Coupling of an Unbiased Carbon Radical Enabled by Perfluoroaryl Semicorrin Ligands

A racemic starting material can be converted into a scalemic product through the intermediacy of a carbon-centered radical if a reactant or catalyst can distinguish its prochiral faces. This differentiation typically relies on proximal Lewis basic functionality or conspicuous steric repulsion, and examples of unbiased radicals are rare. Here, we describe a modification to the semicorrin ligand class that retains its X,L-character but replaces the conserved nitrile group with fluoroarenes, which prove integral to achieve high enantioselectivity with isolated carbon radicals that lack proximal differentiating functionality. Experiment and computation converge on conformationally constraining CF···HC interactions that separate the energies of the diastereomeric transition states of C-C bond formation. Given its distinctive electronic and structural properties, dynamic CF···HC interaction network, and two-step, modular synthesis, we expect this new class of chiral ligands, termed scArF, to fill a unique niche and inspire new ligand designs.