Dimethyl Sulfide → (2R,3S)-3-(Dibenzylamino)pentan-2-ol

To a stirred suspension of CuBr.SMe2 (1.54 g, 7.5 mmol) in anhydrous ether under an argon atmosphere at −78° C., was added methyllithium (1.6M in ether, 9.4 ml, 15 mmol) dropwise. After the addition was complete, the reaction was allowed to warm to room temperature. The reaction was recooled to −78° C. and a solution of (S)-2-(dibenzylamino)butanal (1 g, 3.75 mmol) in ether (20 ml) was added dropwise. After the addition, continued stirring for 2 h The reaction was then quenched with a saturated aqueous solution of NH4Cl (10 ml). The reaction mixture was extracted with ether (2×30 ml) and the combined organic phase washed with brine (20 ml), dried (MgSO4) and evaporated in vacuo. The residue was purified by flash silica gel gradient column chromatography, eluted with hexane:ethyl acetate (100:0→80:20) to afford the product as a light yellow oil (0.95 g, 89%) as the only isomer. δH (250 MHz, CDCl3) 1.05 (3 H, t, J 7.5, CHCH2CH3), 1.25 [3 H, d, J 7.5, CH(CH3)OH], 1.6-1.49 (1 H, m, CHHCH3), 1.88-1.73 (1 H, m, CHHCH3), 2.41 (1 H, s, br, OH), 2.66-2.59 (1 H, m, CHCH2CH3), 3.85-3.65 (4 H, m, 2×CH2Ph), 4.05-3.9 (1 H, m, CHOH), 7.41-7.25 (10 H, m, ArH) δC (250 MHz, CDCl3) 140.05 (2×C), 128.98 (4×CH), 128.37 (4×CH), 127.3 (2×CH), 66.81 (CH), 63.65 (CH), 55.41 (CH2), 20.63 (CH3) 18.44 (CH2), 12.5 (CH3)