AQUEOUS [6-CYCLOADDITIONS OF TROPONE WITH 1-(GLUCOPYRANOSYLOXY)BUTA-1,3-DIENE(4])

The first aqueous [6 + 4] cycloaddition reaction is reported. Starting from tropone and glucopyranosyloxybuta-1,3-diene, bicyclic adducts ar ising from the expected exo-transition state have been obtained in fai r yields under much milder conditions than those usually required, thu s preventing side-[4 + 2] adduct formation by limiting the reversibili ty of the [6 + 4] process. Influence of the solvent is clearly demonst rated as the reaction in methanol is much slower compared with that in water. The best yields : are obtained in buffered solutions or in con centrated aq. sugar solutions.