Mechanism of the heterocyclization of vic-alkynylanthra- and vic-alkynylnaphthoquinone diazonium salts

On the basis of experimental data and of quantum-chemical calculations, a principal scheme for the mechanism of cyclization of vic-alkynylanthra- and vic-alkynylnaphthoquinone diazonium salts resulting in the formation of 5- and 6-membered heterocycles is proposed. Within the framework of the new notions of the reaction mechanism, a possibility of controlling the formation of condensed pyrazole or pyridazine rings is demonstrated.