Reaction Steps
The reaction was run at 0° C. for 20 h with stirring using (E)-4-((benzhydrylimino)methyl)benzonitrile (296 mg, 1.0 mmol, 1.0 equiv) and 10 mol % of (S)—N-benzhydryl-2-(3-(3,5-bis(trifluoromethyl)phenyl)thioureido)-N,3,3-trimethyl butanamide (4e). The product was subjected to purification by flash column chromatography (9:1, hexanes:Et2O) to afford (R)-4-((benzhydrylamino) (cyano)methyl)benzonitrile (310 mg, 0.96 mmol, 96% yield) as a white solid. The enantiomeric excess was determined to be 93% by chiral HPLC analysis (OD-H, 5.0% IPA in hexanes, 1.0 mL/min, 230 nm, tR(major)=41.1 min, tR(minor)=56.4 min); [α]D24=+27.3° (c=1.0, CHCl3). 1H NMR (500 MHz, CDCl3): δ 7.72 (4H, s), 7.57 (2H, d, J=7.5 Hz), 7.45 (2H, d, J=7.5 Hz), 7.39 (2H, t, J=7.8 Hz), 7.29-7.34 (3H, m), 7.23-7.27 (1H, m), 5.25 (1H, s), 4.67 (1H, br s), 2.25 (1H, br s). 13C {1H} NMR (125 MHz, CDCl3): δ 142.2, 140.5, 139.7, 132.7, 129.1, 128.8, 128.2, 128.0, 127.9, 127.4, 127.0, 118.1, 117.7, 113.1, 65.7, 52.0. IR (cm−1): 3310 (m), 3296 (m), 3025 (w), 2925 (w), 2845 (w), 2232 (m), 1609 (w), 1492 (m), 1453 (m), 1349 (m), 1189 (m), 925 (m), 746 (s), 703 (s).
