Studies on the Chemical Transformations of Rotenoids. IV. : Synthesis of Novel Benzofuro[2,3-d]pyridazines Fused with Tetrazole, 1,2,4-Triazole and 1,2,4-Triazine

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Benzofuro[2,3-d]pyridazin-4(3H)-one (1) was converted into 4-chloro-(3) and 4-ethoxy-benzofuro [2,3-d]pyridazine (4). Reaction of 1 with phosphorus pentasulfide provided benzofuro-[2,3-d]pyridazine-4-thione (2), which underwent S-methylation to give the 4-thiomethyl derivative (5). Hydrazinolysis of 2 or 3 proceeded efficiently to give the corresponding 4-hydrazino compound (6). Compound 6 was cyclized with nitrous acid to afford benzofuro[2,3-d]tetrazolo[1,5-b]-pyridazine (7), which was alternatively prepared from 3 or 4 with sodium azide.3-Substituted benzofuro[2,3-d][1,2,4]triazolo[4,3-b]pyridazines (8-12) were prepared by cyclization of 6. Refluxing 6 with ethyl pyruvate in ethanol followed by cyclization in acetic acid provided a novel 4H- benzofuro[2', 3' : 4,5]pyridazino[3,2-c][1,2,4]triazin-4-one (14).
公益社団法人日本薬学会の論文
1988-05-25