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Paper | Regular issue | Vol 43, No. 11, 1996, pp.2457-2464
Published online, 1st January, 1970
DOI: 10.3987/COM-96-7571
Thermal Addition Reaction of Aroylketene with Ethyl Vinyl Ether: Aromatic Substituent Effect on Aroylketene Reactivity

Jun Toda, Toshiaki Saitoh, Taichi Oyama, Yoshie Horiguchi, and Takehiro Sano

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


A series of aroylketenes (2) generated by thermolysis of 5-aryl-2,3-dihydrofuran-2,3-diones (1) reacted with ethyl vinyl ether under a thermal condition to give 2,3-dihydro-4H-pyran-4-ones (3) and/or 4H-pyran-4-ones (4). In this reaction the electron withdrawing substituent (No2, Cl) introduces into the aryl part enhanced the ketene reactivity (2b-e), while the electron donating one (OMe) did not affect its reactivity (2f-g) in a significant extent. The heteroaroylketenes (2h) and (2i) showed a fairly good reactivity.