Potential　energy　surfaces　and　molecular　dynamics　of　the　intramolecular　1,　3-dipolar　cycloaddition　and　ene　reaction　of　a　nitrile　oxide　with　an　alkene　were　performed　in　the　gas　phase　and　in　dichloromethane　with　density　functional　theory.　One　hundred　trajectories　were　propagated　in　the　gas　phase　and　in　dichloromethane,　respectively.　Twenty　percent　of　the　trajectories　in　the　gas　phase　involve　bicyclic　intermediate　and　the　mean　time　gap　is　472fs.　A　dynamically　stepwise　reaction　is　observed.　In　dichloromethane,　more　reactive　trajectories　were　obtained　and　the　time　gap　is　larger　than　that　in　the　gas　phase.　[GRAPHICS]　.