Easy preparation of enantiopure C-2 symmetrical hydroxy and amino sulfides derived from ephedrine and their application in a Pd catalyzed coupling reaction

Ephedrine can be readily converted by means of intramolecular S(N)2 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 tetrabutylammonium fluoride (TBAF) and dithiols affords the C-2 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