[2+2+2] Cycloisomerisation of Aromatic Cyanodiynes in the Synthesis of Pyridohelicenes and Their Analogues

We have developed a methodology for the synthesis of pyridohelicenes and their analogues based on the Ni⁰‐, Co^I‐ or Rh^I‐mediated intramolecular 2+2+2] cycloisomerisation of cyanodiynes. It allows for folding the linear precursors into the corresponding helical backbones comprising the newly formed pyridine unit in their central part. Along with racemic pyridon]helicenes (n=5,6,7) and their derivatives, both enantio‐ and diastereomerically pure pyridon]helicene‐like molecules (n=5,6) were prepared by employing the chiral substrate‐controlled cyclisation of the corresponding enantiopure cyanodiynes.