The synthesis of azahelicenes

Azahelicenes as heteroanalogues of iconic helically chiral helicenes consist of all-ortho-fused carbocycles (mostly benzene core units) and various nitrogen heterocycles. They have recently attracted increasing attention owing to their remarkable shape and unique chemical and physical properties. The first astonishing applications of azahelicenes to chemistry, physics and biology ranging from enantioselective organocatalysis to circularly polarised light detection have appeared. The present review surveys the recent progress in the synthesis of neutral or cationic azahelicenes and their congeners employing a rich portfolio of synthetic methods. The manifold ways to receive nonracemic azahelicenes are also reviewed.