A [2+2+2] cyclization strategy for the synthesis of phosphorus embedding [6]helicene-like structures

Abstract

A Ni(0) promoted intramolecular [2+2+2] cyclotrimerization of triynes provides suitable access to a new series of phosphorus embedding helicenes. [6]Oxahelicenes in which the helical sequence terminates with a phosphole oxide unit have been prepared in both racemic and enantiopure forms and characterized by X-ray diffraction studies.