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The 9-aryl-4-oxynaphthofuran-1(3H)-one system is generally synthesized in two steps from α-aryl-o-toluic acid derivatives. The method involves a tandem conjugate addition–Dieckmann type condensation between α-lithiated α-aryl-o-toluic acid derivatives and 2-furan-2(5H)-one as a key step followed by simple dehydrogenation or dehydration, and can be applied to the synthesis of two natural lignans (neojusticidin A and neojusticidin B).
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Kobayashi et al. (1997) studied this question.
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