New strategy for the construction of epoxy-bridged tetrahydropyran frameworks from trioxane precursors: application to a concise synthesis of a Riesling acetal

A simple one-pot method to prepare dioxabicyclo2.2.1] heptane derivatives, from readily available 1,2,4-trioxane frameworks, under catalytic hydrogenation conditions over a platinum surface is reported. The overall transformation involves the hydrogenation of the double bond and a ring contraction rearrangement that presumably proceeds via a hydrogenolytic cleavage of the O-O bond and subsequent intramolecular ketalization. The strategy was successfully applied to the synthesis of a Riesling acetal.