6-(1'-Formyl)-1,5-dimethoxy-2-(2″-oxopropyl) anthraquinone (1), a key intermediate in Danishefsky's synthesis of vineomycinone B2 methyl ester (5), has been prepared by a new route from anthrarufin (6) via the intermediate 1-methoxy-2-(2′-methylprop-2′-enyl)-5-(2′-methylprop-2′-enyloxy) anthraquinone (20). An alternative synthesis of the diketone (40) has been achieved via Claisen rearrangement of (20) and a subsequent ozonolysis of the resulting bis ( methylpropenyl ) anthraquinone (26). Other routes to (1) from anthrarufin have been developed. In one, compound (1) was formed in yields of 10-16% as an anomalous product from the ozonolysis of (27). Ozonolyses of mixtures of (27), (37) and (44), obtained by isomerization of (27), afforded (1) in yields of 28-43%. Isomerization of the diphenol (25) with palladium(II) chloride bis ( acetonitrile ) in refluxing chloroform proceeds at a faster rate than the isomerization of (27), thereby affording the mono isomerized diphenol (38) in 37% yield. Methylation of (38) affords (37), a known precursor of (1).
6-(1'-甲酰基)-1,5-二甲氧基-2-(2″-氧代丙基)蒽醌(1)是 Danishefsky 合成藤霉素酮 B2 甲酯(5)的关键中间体、通过中间体 1-甲氧基-2-(2′-甲基丙-2′-烯基)-5-(2′-甲基丙-2′-烯氧基)蒽醌(20),以新的路线从蒽藜芦苷(6)制备得到。二酮(40)的另一种合成方法是通过(20)的克莱森重排,然后对生成的双(甲基丙烯基)蒽醌(26)进行臭氧分解。从蒽醌制取(1)的其他途径也已开发出来。其中,(27)的臭氧分解生成的化合物(1)是一种异常产物,产率为 10-16%。由 (27) 异构化得到的 (27)、(37) 和 (44) 混合物的臭氧分解生成了 (1),产率为 28-43%。 二苯酚(25)与氯化钯(II)双(乙腈)在回流氯仿中的异构化速度比(27)的异构化速度快,从而得到单异构化的二苯酚(38),收率为 37%。将(38)甲基化可得到(37),即已知的(1)前体。