Reactive intermediates. Part II. Some addition reactions of benzyne

Benzyne, generated by the oxidation of 1-aminobenzotriazole with lead tetra-acetate, adds to 1,3-dienes and reacts with nucleophiles in moderate to excellent yields. However, it generally dimerises much faster than it adds to heterocyclic dienes. Addition of benzyne to 2-methyl- and 2-benzyl-benzotriazole gives 1-phenylbenzotriazole. Mechanisms for these reactions are proposed. Benzyne, generated oxidatively, does not add appreciably to mono-olefins.