A new approach to the synthesis of pyridazino[4,5-c]pyridazinones |
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| Authors: | Tetsuo Yamasaki Yuji Yoshihara Yoshinari Okamoto Tadashi Okawara Mitsuru Furukawa |
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| Affiliation: | Faculty of Pharmaceutical Sciences, Kumamoto University, Oe-hon-machi, Kumamoto 862, Japan |
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| Abstract: | The reaction of 5-hydrazinopyridazin-3(2H)-ones 1 with α-keto diester 2 in acetic acid afforded the corresponding 4,6-dihydropyridazino[4,5-c]pyridazin-5(1H)-ones 3 and pyrrolo[2,3-d)pyridazin-4(5H)-ones 4 . Compounds 3 were also obtained from 4-bromo-5-hydrazinopyridazin-3(2H)-ones 8 and 2 under milder conditions. 5-Bromo-4-hydrazinopyridazin-3(2H)-one 9 , the regioisomer of 8b , also reacted readily with 2a to give 4,7-dihydropyridazino[4,5-c]pyridazin-8(1H)-one 10b , the regioisomer of 3b . |
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