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