Efficient routes to pyrazolo[3,4-e][1,2,4]triazines and a new ring system: [1,2,4]triazino[5,6-d][1,2,3]triazines.
Arylhydrazonomalononitriles 1a,b react with phenylhydrazine to yield amidrazones 2a,b that cyclize to give 2-aryl-5-phenylhydrazono-2,5-dihydro-[1,2,4]-triazine-6-carbonitriles 5a,b upon reaction with dimethylformamide dimethylacetal (DMFDMA). Refluxing 5a,b in glacial acetic acid resulted in the formation of the pyrazolo-1,2,4-triazines 6a,b. Compounds 6a,b were also formed upon treatment of 3-amino-4-phenylhydrazono-1-phenyl-2-pyrazolin-5-ones 7a,b with DMFDMA. Reacting these triazinyl arylhydrazononitriles 5a,b with hydroxylamine hydrochloride in ethanolic sodium acetate afforded amidrazones 8a,b that are readily cyclized in refluxing dimethylformamide into [1,2,4]triazino[1,2,3]triazines 10a,b.
Al-Matar
Hamad Mohamed
HM
Chemistry Department, Faculty of Science, University of Kuwait, P.O. Box 5969, Safat 13060, Kuwait. h.almatar@ku.edu.kw
Khalil
Khaled Dessouky
KD
Al-Dorri
Doa'a Mohamed
DM
Elnagdi
Mohamed Helmy
MH
D003500:Cyclization; D009570:Nitriles / Q000737:chemistry; D010659:Phenylhydrazines / Q000737:chemistry; D047069:Pyrazolones / Q000138:chemical synthesis*; D014227:Triazines / Q000138:chemical synthesis*
D009570:Nitriles; D010659:Phenylhydrazines; D047069:Pyrazolones; D014227:Triazines; C030299:phenylhydrazine; C093444:1,2,4-triazine