An intermolecular Diels-Alder cycloaddition under various condition between 1,3-cyclohexadiene and 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate

The reaction between 1,3-cyclohexadiene and dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate both without a catalyst and with different catalysts, in both atmospheric and at high pressure, over 20 days were studied. At the end of the reactions, different products (retro Diels-Alder addition product 5 and Diels-Alder addition product 6 ) were obtained in different yields. When we look at the percentage of the addition product, it is observed that the yield of reaction at high pressure in water is the highest. All structures of these products were characterized by 1H-NMR, 13C-NMR, MS, and IR spectroscopy.