THE PRACTICAL SYNTHESIS OF DISSYMMETRICAL 1,3,5-TRIOXAZATRIQUINANE DERIVATIVES COMPRISED OF THREE DISTINCT CARBONYL COMPOUNDS

We have previously synthesized various 1,3,5-trioxazatriquinane derivatives consisting of not only three identical carbonyl compounds but also two identical carbonyl moieties as well as another type of carbonyl compound. However, dissymmetrical derivatives prepared from three distinct carbonyl compounds have not yet been selectively synthesized. Herein, we developed a selective synthetic method of such dissymmetrical derivatives: free a-hydroxyaldehydes were slowly added to a solution of protected a-hydroxyaldehydes, ammonium chloride, and sodium acetate to selectively provide key intermediate oxazolines, which were successfully converted into the objective dissymmetrical derivatives.