Ring-Expansion of Bridgehead Aldehydes with 1-Adamantanecarbonyl Cation or Benzoyl Trifluoromethanesulfonate: A New Route to Bicyclic and Tricyclic 1,2-Diols

Article abstract of DOI:10.1055/s-1987-28022

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 acyloxy 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.