Dibromobenzoisofuranone 12, synthesized in six steps, was regiospecifically annulated with 5-substituted cyclohexenones 13/36 in the presence of LiOt-Bu to give brominated anthraquinones 14/38 in good yields. Darzens condensation of 30 was shown to give chain-elongated anthraquinone 32. Alkaline hydrolysis of 38 furnished 39 representing desulfoproisocrinin F.
二
溴苯并异
呋喃酮12,经过六步合成,与5-取代
环己烯酮13/36在LiOt-Bu存在下特异地发生环化反应,产率良好地得到
溴代
蒽醌14/38。对30进行Darzens缩合反应得到链延伸的
蒽醌32。对38进行碱性
水解得到39,代表去
硫代异柠檬素F。