Functionalization of Aromatic Azo Compounds by the Cobalt‐Catalyzed, Regioselective Double Addition of Tolane: 2,6‐Distilbenylazobenzenes and 2,3‐Dihydrocinnolines

Abstract

The substitution pattern determines whether distilbenylazobenzene compounds 1 or their subsequent products, the dihydrocinnolines 2, are isolated in the cobalt-catalyzed solvent-free reaction of azo compounds with diphenylacetylene. For several derivatives a photochromic equilibrium exists between the two forms.