Acetic Acid → Rac-2-cyclopropylaminomethyl-2,5-dimethyl-hexanoic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

Cyclopropylamine (1.00 mL, 14.4 mmol), glacial acetic acid (1.0 mL), and sodium cyanoborohydride (1.82 g, 29.0 mmol) were added sequentially to a solution of crude rac-2-formyl-2,5-dimethyl-hexanoic acid ethyl ester (2.90 g, 14.5 mmol) in ethanol (40 mL) at 25° C. The mixture was stirred at 25° C. for 18 h, and then was 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 (self-packed glass column, gradient elution: 20-30% ethyl acetate in hexanes) to afford rac-2-cyclopropylaminomethyl-2,5-dimethyl-hexanoic acid ethyl ester (1.33 g, 5.51 mmol, 38%) as a pale yellow oil. 1H NMR (400 MHz, CDCl3) δ: 0.00-0.04 (2H, m), 0.12-0.16 (2H, m), 0.62 (6H, d, J=6.4 Hz), 0.76-0.86 (1H, m), 0.88 (3H, s), 1.00 (3H, t, J=6.9 Hz), 1.12-1.25 (2H, m), 1.30-1.38 (2H, m), 1.82-1.87 (1H, m), 2.38 (1H, d, J=11.7 Hz), 2.67 (1H, d, J=11.9 Hz), 3.86 (2H, q, J=6.9 Hz).

Provenance & Evidence