Treatment of (+)-2'-demethoxydehydrogriseofulvin (2b) with magnesium iodide afforded 5-chloro-2, 8-dihydroxy-6-methoxy-4-methylxanthone (3a) via dienone-phenol rearrangement. The structure of 3a was determined by means of a carbon-13 nuclear magnetic resonance (13C-NMR) long-range selective proton decoupling (LSPD) experiment performed on its diacetate 3b. The rearrangement of 2b was also effected with p-toluenesulfonic acid to give 5-chloro-6, 8-dimethoxy-2-hydroxy-4-methylxanthone (6a). On the other hand, reaction of (-)-dehydrogriseofulvin (2d) with p-toluenesulfonic acid under more vigorous conditions resulted in racemization, no rearrangement being observed.
对(+)-2'-去甲氧基去
氟酮(2b)与
碘化镁反应,通过烯酮-
酚重排生成了5-
氯-2, 8-二羟基-6-甲氧基-4-甲基
黄烷酮(3a)。3a的结构通过对其二
醋酸酯3b进行的碳-13核磁共振(13C-NMR)长程选择性质子去耦实验确定。使用对
苯磺酸处理2b也实现了重排,生成了5-
氯-6, 8-二甲氧基-2-羟基-4-甲基
黄烷酮(6a)。另一方面,(-)-去
氟酮(2d)与对
苯磺酸在更强烈的条件下反应,导致了外消旋化,没有观察到重排。