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

Participants

Reaction Conditions

Reaction Steps

Cyclopentylamine (1.49 mL, 15.1 mmol), glacial acetic acid (1.5 mL), and sodium cyanoborohydride (1.90 g, 30.2 mmol) were added sequentially to a solution of crude rac-2-formyl-2,5-dimethyl-hexanoic acid ethyl ester (prepared as described in Example 19c; 3.02 g, 15.1 mmol) in ethanol (45 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-cyclopentylaminomethyl-2,5-dimethyl-hexanoic acid ethyl ester (1.60 g, 5.94 mmol, 39%) as a pale yellow oil. 1H NMR (400 MHz, CDCl3) δ: 0.87 (6H, d, J=6.9 Hz), 1.01-1.06 (1H, m), 1.16 (3H, s), 1.27 (3H, t, J=6.9 Hz), 1.27-1.33 (4H, m), 1.43-1.64 (8H, m), 2.51 (1H, d, J=11.7 Hz), 2.79 (1H, d, J=11.7 Hz), 2.96-3.02 (1H, m), 4.12 (2H, q, J=7.2 Hz).

Provenance & Evidence