Aqueous [6 + 4] cycloadditions of tropone with 1-(glucopyranosyloxy)buta-1,3-diene

Abstract

The first aqueous [6 + 4] cycloaddition reaction is reported. Starting from tropone and glucopyranosyloxybuta-1,3-diene, bicyclic adducts arising from the expected exo-transition state have been obtained in fair yields under much milder conditions than those usually required, thus preventing side-[4 + 2] adduct formation by limiting the reversibility of the [6 + 4] process. Influence of the solvent is clearly demonstrated as the reaction in methanol is much slower compared with that in water. The best yields are obtained in buffered solutions or in concentrated aq. sugar solutions.