Diels–Alder reactions: The effects of catalyst on the addition reaction

• The structure of products was determined from X-Ray, NMR, MS and IR analysis.
• We synthesized tricylocyclitol and dioxatricyclo derivatives.
• Cycloaddition reactions examined both without catalyst and different catalysts.

The reaction between 2,3-dimethyl-1,3-butadiene and dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate is efficiently achieved with small amounts of catalyst, i.e. phenol, AcOH, nafion, and β−cyclodextrin. Exo-diastereoselective cycloaddition reactions were observed both without catalyst and different catalysts for 48 days. As a result, different products (tricyclicmolecule 5, retro-Diels–Alder product 6, and oxidation product 7) were obtained with different catalysts. In addition, we synthesized Diels–Alders product 8 and tricyclocyclitol 10 via Diels–Alder reaction. The structures of these products were characterized by 1H NMR, 13C NMR, MS and IR spectroscopy.

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