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Paper | Special issue | Vol 47, No. 1, 1998, pp.315-327
Published online, 1st January, 1970
DOI: 10.3987/COM-97-S(N)19
A New Approach to Fused 1,2-Diazepines by Cyclization of Enhydrazines with α- and β-Keto Esters

Tetsuo Yamasaki,* Kaoru Nishida, Yoshinari Okamoto, Tadashi Okawara, and Mitsuru Furukawa

*Faculty of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-hon-machi, Kumamoto 862-0973, Japan


The cyclization of 6-(1,2-diethoxycarbonylethylidene)hydrazino-1,3-dimethyluracil (3) and 6-(1,2-diethoxycarbonylethylidene)hydrazino-3-methyl-2-methylthiopyrimidin-4(3H)-one (8) in the presence of polyphosphoric acid (PPA) provided 2,5-dihydropyrimido[4,5-c]-1,2-diazepine-5,6,8(1H,7H,9H)-trione (4) and 4,5-dihydropyrimido[4,5-c]-1,2-diazepine-5,6(1H,7H)-dione (9), respectively. 4-Hydrazino-5-methyl-2-pyrone (27) and 5,5-dimethyl-3-hydrazinocyclohexen-1-one (31) readily reacted with ethyl benzoylacetate (28) to give 4,5-dihydropyrano[4,3-c]-1,2-diazepine-5,6(1H,7H)-dione (30) and 3-phenyl-1,8,8-trimethyl-4,5,6,7,8,9-hexahydro-1,2-benzodiazepine-5,6(1H)-dione (33), respectively.