Synthese der citromycinone stereoselektive öffnung eines epoxids zum cis-diol

The citromycinone-derivatives $\text{14}$ and $\text{15}$ have been obtained by intramolecular Marschalk cyclisation of α-hydroxyaldehyde $\text{12}$. An unexpected opening of epoxide $\text{16}$ to $\text{cis}$-diol $\text{14}$ was observed. By exclusion of the alternative formula $\text{2}$ structure $\text{3}$ is proposed for α-citromycinone.