Stereocontrolled Construction of Multi-Chiral [2.2]Paracyclophanes via Cobaltaphotoredox Dual Catalysis
Yang Xu, Neeraj Kumar Pandit, Silvia Meraviglia, Philipp Boos, Paula Kallenbach, Max Surke, Regine Herbst‐Irmer, Dietmar Stalke, Lutz Ackermann
Abstract
-disubstituted multichiral [2.2]-paracyclophanes (PCPs) represent privileged scaffolds for asymmetric catalysis, finding extensive applications as chiral ligands in organic synthesis and functional materials. However, enantioselective C-H activation strategies for accessing these structurally demanding molecules remain largely underexplored. We report a synergistic strategy combining photoredox catalysis with enantioselective cobalt-catalyzed C-H activation that enables efficient construction of central chiral and planar chiral PCP derivatives through kinetic resolution. This method provides access to diverse disubstituted multichiral PCPs in good yields with exceptional levels of enantioselectivity (>20:1 dr, >99% ee) while simultaneously recovering the unreacted enantiomer in a high optical purity (up to 50% yield, >99% ee). Computational studies reveal the favorable pathway for a single enantiomer of the racemic PCP, rationalizing the observed enantioselectivity in terms of attractive dispersion interactions emerging as key contributors during the enantiodetermining step. The synthetic utility is demonstrated through: (1) gram-scale continuous photoflow synthesis with maintained efficiency and (2) versatile downstream functionalization of the products into valuable PCP-based ligands. Our findings represent a paradigm shift for the synthesis of sterically congested chiral PCP architectures, significantly expanding the toolbox for asymmetric synthesis and chiral material design.