Didehydrohetarenes (XXXVII). On the existence of 4,5-didehydropyridazine

Reaction of 4-chloro-3,6-diphenylpyridazine with potassium amide in liquid ammonia gives 4-amino-3,6-diphenylpyridazine and imino-4,4′-bis(3,6-diphenylpyridazine). Starting with 4-chloro-3,6-diphenylpyridazine-[5-13C], it was proved by quantitative 13CNMR measurements that both products are formed via the intermediacy of 4,5-didehydro-3,6-diphenylpyridazine.