Although PhTD (4-phenyl-substituted 1, 2, 4-triazoline-3, 5hdione) has been reported to be one of the most reactive dienophiles' and enophiles? only the DA (Diels-Alder) reactions have been extensively investigated. However, in a study of the ene reactions of PhTD with a series of substituted alkenes, bicycloalkanes as well as bicycloalkenes have been reported re~ ently.~ The reaction of PhTD and styrene at room temperature was reported to give a ...