Synthesis of New Phosphahelicene Scaffolds and Development of Gold(I)‐Catalyzed Enantioselective Allenene Cyclizations

This paper reports on the development of an efficient synthesis of enantiopure phospha6]helicenes through a 2+2+2] alkyne cyclotrimerization reaction. The corresponding gold complexes proved to be highly efficient both in terms of catalytic activity and enantioselectivity in 2+2] and 4+2] cycloaddition reactions. Furthermore, in the presence of an external nucleophile, such as water or alcohols, the tandem cyclization/addition reactions take place in high yields and excellent diastereo‐ and enantioselectivities.