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Communication | Regular issue | Vol 3, No. 5, 1975, pp.381-388
Published online, 1st January, 1970
DOI: 10.3987/R-1975-05-0381
Pyridopyridazines. IV. Pyrido[2,3-d]pyridazine N-Oxides. A Novel Ring-Opening Reaction by Means of Acetic Anhydride

Ikutoshi Matsuura*

*Central Research Laboratories, Chugai Pharmaceutical Company, Ltd., Takada 3-41-8, Toshima-ku, Tokyo 171, Japan


Treatment of 5-alkoxypyrido[2,3-d]pyridazines with m-chloroperbenzoic acid afforded the 7-oxides 2a and 2b, and the 1,7-dioxides 3a and 3b. 8-Alkoxypyrido[2,3-d]pyridazines however yielded the 6-oxides 2c and 2d. Of the mono-oxides 2b and 2d on treatment with acetic anhydride gave the ring-opened esters 5b and 5d and the ketoesters 6b and 6d. 1-Methoxyphthalazine-3-oxide similarly yielded benzoate 10, acetonylbenzoate 11, and methyl stilbenedicarboxylate 12.