| 摘要 |
PURPOSE:To produce the titled compound useful as dyes, pharmaceuticals or their raw material, in one step, by using a specific naphthazarin derivative and a specific cyclic acetal or its derivative as easily available raw materials and reacting the compounds in the presence of an acid catalyst. CONSTITUTION:The objective naphthazarin derivative of formula III [e.g. 5,8- dihydroxy-2-(tetrahydro-5,5-dimethyl-2-furanyl)-1,4-naphthalenedione] can be produced by reacting (A) the compound of formula I (X1-X3 are H, OH, organic residue or halogen) (e.g. naphthazarin) with the compound of formula II (R is H, hydrocarbon residue or acyl; R1-R6 are H or hydrocarbon residue) (e.g. tetrahydro-5,5-dimethyl-2-phenyl acetate) in the presence of an acid catalyst (e.g. BF3-etherate). EFFECT:Shikonin or alkannin can be synthesized easily from the titled compound.
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