An Enantioselective Oxidative C–H/C–H Cross-Coupling Reaction: Highly Efficient Method To Prepare Planar Chiral Ferrocenes

A Pd-catalyzed, asymmetric
oxidative cross-coupling reaction between
ferrocenes and heteroarenes is described. The process, which takes
place via a twofold C–H bond activation pathway, proceeds with
modest to high efficiencies (36–86%) and high levels of regio-
and enantioselectivity (95–99% ee). In the reaction, air oxygen
serves as a green oxidant and excess amounts of the coupling partners
are not required. The process is the first example of a catalytic
asymmetric biaryl coupling reaction that occurs via double C–H
bond activation. Finally, the generated coupling products can be readily
transformed into chiral ligands and catalysts.