Ephedrine can be readily converted by means of intramolecular SN2 substitution by the hydroxyl or amino substituent into, respectively, the corresponding epoxide or aziridine with high stereocontrol. Subsequent stereoselective ring opening at the benzylic centre using tetrabutyl‐ammonium fluoride (TBAF) and dithiols affords the C2 symmetrical hydroxy or amino sulfides in excellent yield. Application of these ligands in a palladium‐catalyzed asymmetric allylic substitution reaction gave moderate to high enantiomeric excesses (up to 79%) and high yields of product.
Koning, B., Hulst, R., & Kellogg, R. M. (1996). Easy preparation of enantiopure C@2# symmetrical hydroxy and amino sulfides devired from ephedrine and their application in a Pd catalyzed coupling reaction. Recueil des travaux chimiques des Pays-Bas, 115(1), 49-55. https://doi.org/10.1002/recl.19961150110