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Note | Regular issue | Vol 60, No. 7, 2003, pp.1689-1695
Published online, 9th June, 2003
DOI: 10.3987/COM-03-9790
Synthesis of Benzo[1,2-b:5,4-b’]dithiophene-4,8-dione Derivatives

Kazuhiro Kobayashi,* Toshikazu Ogata, Kazuna Miyamoto, Osamu Morikawa, and Hisatoshi Konishi

*Department of Materials Science, Faculty of Engineering, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan


4,7-Dioxo-4,7-dihydrobenzo[b]thiophene-2-carboxylates (1) underwent regioselective acylation at the 5-position with a range of aldehydes under irradiation to give the corresponding 5-acyl-4,7-dihydroxybenzo[b]thiophene-2 carboxylates (2), which were then oxidized with Ag2O to afford 5-acyl-4,7-dioxo 4,7-dihydrobenzo[b]thiophene-2-carboxylates (3). These acylated benzothiophenquinone derivatives were transformed in one-pot to 4,8-dioxo-4,8 dihydrobenzo[1,2-b:5,4-b’]dithiophene-2,6-dicarboxylates (5) by treatment with mercaptoacetates, followed by 1-trimethylsilylimidazole-mediated cyclization and cerium(IV) ammonium nitrate (CAN) oxidation.