Atroposelective Synthesis of Biaryl N-Oxides via Cu-Catalyzed De Novo Heteroaromatic N-Oxide Ring Formation

The study introduces an atroposelective synthesis method for biaryl N-oxides using a Cu-catalyzed process, achieving a 99% yield and a 95.5:4.5 enantiomeric ratio. This method, involving Cu(CH3CN)4PF6 and a chiral ligand, shows broad substrate compatibility and high stereoselectivity. The synthesized N-oxides have potential as Lewis base catalysts and exhibit significant antitumor activity, particularly compound 3e, which shows promise against breast cancer cells with IC50 values of 4.8 and 5.2 µm. The research enhances synthetic capabilities in heteroaromatic N-oxides, with implications for drug development and asymmetric catalysis.