Studies on the Reaction of α‐Chloroformylarylhydrazine Hydrochloride 1 with N‐Heterocyclic Compounds

In addition to pyridines, α‐chloroformylarylhydrazine hydrochloride 1 can also react with some N‐heterocyclic compounds. The cycloaddition of 1 with isoquinoline was achieved to obtain 3 . The production of 4, 5, 6 given by cycloaddition of 1 with pyridazine was de pendent on the reaction condition. Some heterocyclic compounds bearing an X‐C=N (X:S, N) group on the ring can react with 1 to gain the derivatives of 2,4‐dihydro‐1,2,4‐triazol‐3‐one. 7, 8, 9 and 10 were given by reaction of 1 with 1,3,5‐triazine, 1,4,5,6‐tetrahydropyrimidine, 1,3‐thiazole and 2‐amino‐1,3‐thiazole, respectively. The reactions for 2‐amino‐1,3,4‐thiadiazole and 3‐amino‐1,2,4‐triazole had the same product 11 .