Hence, it was envisioned that the norbornene derivative target molecule (TM) (1) would be obtained following a functional group interconversion step. This latter consists in simply reducing the aldehyde (2) to the corresponding alcohol (1) with Lithium Alumino hydride LiAlH 4 . The second retro-synthetic step consists in introducing the norbornene moiety via an asymmetric Diels-Alder reaction, involving the addition of the freshly distilled cyclopentadiene to the chiral(E)-crotonyl derivative (3). Under the following conditions; low temperature -78°C, in the presence of tin tetrachloride TiCl 4 catalyst and in the solvent dichloromethane, the endo product (2) is obtained predominantly. The minor isomer (exo adduct) could justify the observed reactivity the π face differenciation in the Diels-Alder step which could be explained by the chelation of the sulfone group -SO 2 and the carbonyl group by the Titanium metal of the catalyst. This crucial step will be further explained in the next section when discussing results. (((This chelation will prevent the racemization of the cycloadduct by inhibiting the free rotation of the σ C-N bond of the conformer (3') shown in Fig. .The conformation being locked, the diene will be directed to the less hindered bottom face. )))