The First Helical-Chiral Phosphane Ligands: rac-[5]- and rac-[6]-Heliphos

Abstract
The syntheses of two helical, chiral phosphanes in their racemic forms are described. Their helicene backbone was built up using an improved photocyclization approach. The phosphorus functionalities were introduced in the last step. Up to now, separation of the enantiomers of the helicene phosphanes could be achieved analytically but not on a preparative scale.