Abstract: The Diels-Alder reaction of various reactive dienophiles with cyclopentadiene is reported. Rather than cracking dicyclopentadiene in a separate step, the reagents were mixed in a sealed tube and the reactions carried out at 185C. Conversion to the adducts is dependent on the nature of the dienophile and the reaction time. In those cases where stereochemistry is relevant, the endo/exo ratios are reported and compared to those reported at lower temperatures.