Enantioselective Synthesis of 1‐Aryl Benzo[5]helicenes Using BINOL‐Derived Cationic Phosphonites as Ancillary Ligands

Abstract The synthesis of unprecedented BINOL‐derived cationic phosphonites is described. Through the use of these phosphanes as ancillary ligands in Au I catalysis, a highly regio‐ and enantioselective assembly of appropriately designed alkynes into 1‐(aryl)benzo[5]carbohelicenes is achieved. The modular synthesis of these ligands and the enhanced reactivity that they impart to Au I ‐centers after coordination have been found to be the key features that allow an optimization of the reaction conditions until the desired benzo[5]helicenes are obtained with high yield and enantioselectivity.