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Communication | Regular issue | Vol 16, No. 3, 1981, pp.363-366
Published online, 1st January, 1970
DOI: 10.3987/R-1981-03-0363
2-Azabicyclo[3.2.0]heptane-3,4-diones (3): Lewis Acid Catalysed Ring Expansion of 3-Ethoxy-Δ2-azabicyclo[3.2.0]heptan-4-ones: Synthesis of 2-Ethoxy-3-azatropones

Takehiro Sano,* Yoshie Horiguchi, Suetaka Kambe, and Yoshisuke Tsuda

*Showa Pharmaceutical University, 3-3165, Higashi-tamagawagakuen, Machida, Tokyo 194-8543, Japan

Abstract

Treatment of 2-azabicyclo[3.2.0]heptane-3,4-dione imidic ester (6) with tin(IV) chloride gave the dihydroazatropolone 2-ethyl ethers (7) in moderate yields which were also obtained by reaction of dihydroazatropolones (2) with Meerwein reagent. DDQ oxidation of 7 gave 2-ethoxy-3-azatropones (8), which rearranged, on treatment with water, into ethyl pyridine 2-carboxylate (10). Spectroscopic data of azatropolone 2-ethyl ethers were also described.