反应详情

温度

25 °C

4-Fluorobenzaldehyde (0.622 mL, 5.80 mmol), sodium acetate (0.951 g, 11.6 mmol), powdered/activated 4 Å molecular sieves (2.0 g) and sodium cyanoborohydride (0.729 g, 11.6 mmol) were added sequentially to a solution of racemic 3-amino-2-methyl-propionic acid ethyl ester hydrochloride (0.972 g, 5.80 mmol) in methanol (30 mL) at 25° C. The mixture was stirred at 25° C. for 20 h, and then was filtered through Celite. The Celite was washed with methanol (2×30 mL) and the combined filtrate and washings were concentrated in vacuo. The residue was partitioned between half-saturated aqueous sodium bicarbonate solution (150 mL) and ethyl acetate (2×150 mL). The combined organic layers were dried over sodium sulfate and were concentrated in vacuo. The residue was purified by flash column chromatography (Teledyne Isco RediSep column; 0-80% ethyl acetate in hexanes) to afford rac-3-(4-fluoro-benzylamino)-2-methyl-propionic acid ethyl ester (0.821 g, 3.43 mmol, 59%) as a pale yellow oil. 1H NMR (400 MHz, CDCl3) δ: 1.18 (3H, d, J=7.2 Hz), 1.26 (3H, t, J=6.9 Hz), 2.63-2.72 (2H, m), 2.84-2.91 (1H, m), 3.75 (1H, d, J=13.3 Hz), 3.79 (1H, d, J=13.4 Hz), 4.14 (2H, q, J=6.9 Hz), 6.97-7.01 (2H, m), 7.25-7.29 (2H, m).

1. filtrationwas filtered through Celite
2. washThe Celite was washed with methanol (2×30 mL)
3. concentrationthe combined filtrate and washings were concentrated in vacuo
4. customThe residue was partitioned between half-saturated aqueous sodium bicarbonate solution (150 mL) and ethyl acetate (2×150 mL)
5. dry with materialThe combined organic layers were dried over sodium sulfate
6. concentrationwere concentrated in vacuo
7. customThe residue was purified by flash column chromatography (Teledyne Isco RediSep column; 0-80% ethyl acetate in hexanes)