Acylation of bridgehead aldehydes with 1-adamantanecarbonyl cation generated from 1-adamantyl cation and carbon monoxide, or with benzoyl trifluoromethanesulfonate, in the presence of trifluoromethanesulfonic acid causes ring-expansion of the aldehydes by one carbon atom. Work-up of the reaction mixture with water affords a bridgehead alcohol containing the acyloxyl group on the vicinal carbon, which on saponification gives a vicinal glycol in good overall yields. For example, bicyclo[2.2.1]heptane-1-carbaldehyde gives bicyclo[2.2.2]octane-1,2-diol which is not easily accessible by the other methods.
在
三氟甲磺酸存在下,桥头醛与由 1-
金刚烷阳离子和
一氧化碳生成的 1-
金刚烷羰基阳离子或与
三氟甲磺酸苯甲酰酯发生酰化反应,会使醛环扩张一个碳原子。将反应混合物加
水处理后,可得到在邻接碳上含有酰氧基的桥头醇,皂化后可得到邻接二醇,总产率很高。例如,
双环[2.2.1]庚烷-1-
甲醛可生成
双环[2.2.2]辛烷-1,2
-二醇,而其他方法很难获得这种物质。