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■ A Convenient Method for the Synthesis of 9-Aryl-4-methoxynaphtho[2,3-c]furan-1(3H)-ones

Kazuhiro Kobayashi,* Yasuhiro Kajimura, Kouji Maeda, Tomokazu Uneda, Osamu Morikawa, and Hisatoshi Konishi

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

Abstract

A three-step procedure for the synthesis of the title lignan lactone derivatives is described. The route involves a tandem Michael addition/cyclization reaction between o-aroyl-α-methoxybenzyllithiums, which are generated in situ by the treatment of aryl 2-methoxymethylphenyl ketones with lithium diisopropylamide (LDA) in THF at -78 °C, and furan-2(5H)-one to give the corresponding 9-aryl-9-hydroxy-4-methoxy-3a,4,9,9a-tetrahydronaphtho[2,3-c]furan-1(3H)-ones in moderate to good yields. These products are readily transformed into the title naphthofuranones by dehydration with thionyl chloride in pyridine, followed by aromatization with palladium on activated carbon.