Synthesis of spiroannulated and 3-arylated 1,2,4-trioxanes from mesitylol and methyl 4-hydroxytiglate by photooxygenation and peroxyacetalization

Cycloalkanones were utilized in the Lewis acid catalyzed peroxyacetalization of ß-hydroperoxy homoallylic alcohols (prepared by the ene reaction of the allylic alcohols mesitylol and methyl 4-hydroxytiglate, respectively, with singlet oxygen) to give spiroannulated 1,2,4-trioxanes 5a–5e and 9a–9e, respectively. A second series of 3-arylated trioxanes 10a–10h, that are available from the hydroperoxy alcohol 4 and benzaldehyde derivatives, was investigated by X-ray crystallography.