2-(2′-Furfuryl)-N-acryloyl tetrahydro-1,3-benzoxazine 2a participates in diastereoselective intramolecular Diels-Alderreaction in very mild conditions leading to two diastereoisomeric exo-adducts with good diastereoselectivity. Chromatographic separation of both adduts, and further elimination of the menthol appendage allows to prepare enantiopure iso-indoline derivatives in excellent chemical yields.