Pd-Catalyzed Highly Enantioselective Synthesis of Planar Chiral Ferrocenylpyridine Derivatives

A highly efficient synthesis of planar chiral ferrocenylpyridine derivatives via Pd-catalyzed intramolecular C–H arylation was developed, and quantitative yields and excellent enantioselectivity were obtained for a wide range of substrates. Notably, the catalyst loading could be lowered to 0.2 mol %, which represents the highest catalytic efficiency found for asymmetric C–H bond activation (TON up to 495). These compounds could be easily transformed to pyridine N-oxides, displaying promising catalytic reactivity in the asymmetric opening of meso-epoxide. Moreover, computational investigations were conducted to clarify the origin of the excellent enantioselectivity. The compatibility of large-scale synthesis and low catalyst loading should enhance the practicality of the synthetic application of the current method.