Abstract

A Au-catalyzed protocol for the enantioselective synthesis of molecular architectures containing an internal [5]helicene and two peripherical axial stereogenic elements is described. While the diasteroselectivity of the double alkyne hydroarylation sequence is not optimal, and mixtures that contain similar amounts of two of the four possible diasteromeric products are obtained (one C₂ and one non-symmetric), the assembly of the C₂-symmetric isomer often occurs with high enantioselectivity (up to 98 % ee). The absolute configurations of the products obtained were determined by X-ray crystallography. Studies on the thermal racemization of the internal [5]helicene moiety in the C₂-symmetric isomers determined the half-life of this element to be approximately 3 h at 50 °C.