Synthesis of planar chiral biferrocenes by iridium-catalyzed [2+2+2] cycloadition of a biferrocene-linked diyne with nitriles: asymmetric desymmetrization and kinetic resolution

Abstract

We report a method for the synthesis of planar chiral biferrocenes by iridium-catalyzed asymmetric [2+2+2] cycloaddition of biferrocene-linked diynes with nitriles. The combination of an iridium catalyst and a chiral bisphosphine ligand enabled the asymmetric [2+2+2] cyclization of a meso biferrocene-linked diyne via asymmetric desymmetrization. Furthermore, the [2+2+2] cyclization of a racemic biferrocene-linked diyne proceeded through kinetic resolution.