Propranolol exist in two different enantiomers, (S)-(−)- and (R)-(+)-enantiomers. The (S)-isomer is 100-fold more potent than the (R)-isomer and that is the general rule for most β-blockers. It is possible to produce the (S)-propranolol enantiomer from α-naphthol and 3-bromopropanol as seen in figure 6. α-Naphthol and 3-bromopropanol are refluxed for 6 hours to give alcohol. The alcohol is oxidized by using 2-Iodoxybenzoic acid (IBX) to give aldehyde. The aldehyde is subjected to -proline catalyzed asymmetric α-aminoxylation and a reduction is made with NaBH in methanol. A diol is obtained by Pd/C-catalyzed hydrogenolysis. Finally the diol is converted  to epoxide using the Mitsunobu reaction and stirred with isopropyl amine in CHCl to give (S)-propranolol.