A new approach to fused 1,2-diazepines by cyclization of enhydrazines with alpha- and beta-keto esters

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)...

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Bibliographic Details
Published inHeterocycles Vol. 47; no. 1; pp. 315 - 327
Main Authors Yamasaki, T, Nishida, K, Okamoto, Y, Okawara, T, Furukawa, M
Format Journal Article
LanguageEnglish
Published OXFORD Elsevier 01.01.1998
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
HETEROCYCLIZATION
PYRIMIDO<4,5-C>PYRIDAZINES
DIMETHYL ACETYLENEDICARBOXYLATE
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Summary: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-hydrazinnocyclohexen-1-one (31) readily reacted with ethyl benzoylacetate (28) to give 4,5-dihydropyrano[4,3-c]-1,2-diazepine-5 (30) and 3-phenyl-1,8,8-trimethyl-4,5,6,7,8,9-hexahydro-1,2-benzodiazepine-5,6(1H)-dione (33), respectively.
ISSN:0385-5414
DOI:10.3987/COM-97-S(N)19