(-)-Bis[(S)-1-phenylethyl]amine

synthetischePreparative Methods of (-)-(S,S)-α,α′-Dimethyldibenzylamine: minor improvements to the original catalytic hydrogenation procedure have been described (eq 1). This method provides (S,S)-(-)-(1) with an optical purity of only 70%. Enantiomerically pure (S,S)-(-)-(1) can be obtained by recrystallization of the hydrochloride salt of this enriched material from water or the benzoate salt from isopropanol. A chemical reduction procedure has also been described that yields optically active (S,S)-(1) with 74% enantiomeric excess (eq 2). A significant improvement to the former procedures is the diastereoselective hydrogenation of imines catalyzed by rhodium/chiral diphosphines, which yields (S,S)-(1) with an optical purity of 99.4% (eq 3).