Acetic Acid → (1R,2S)-2-(3-chloro-4-fluoro-benzylamino)-cyclopentanecarboxylic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

(1R,2S)-2-Amino-cyclopentanecarboxylic acid methyl ester hydrochloride (prepared as described in Example 11a, 0.2 g, 1.27 mmol) was dissolved in methanol (5.5 mL), followed by addition of 4-fluoro-3-chlorobenzaldehyde (0.201 g, 1.27 mmol) and stirred at 25° C. for 10 min. After this time, 5.2 M acetic acid (0.245 mL) was added, stirred at 25° C. for 5 min before placing in an ice-bath. Once at 0° C., sodium borohydride (0.203 mg, 3.2 mmol) was added portionwise after which time the mixture was allowed to warm to 25° C. and continued to stir for 17 h. The reaction mixture was quenched by pouring into saturated aqueous sodium bicarbonate solution (200 mL) and extracted with ethyl acetate (200 mL). The organic layer was concentrated in vacuo and purified by flash column chromatography (Teledyne Isco RediSep Flash Column; 0-80% ethyl acetate in hexanes) to afford the desired product, (1R,2S)-2-(3-chloro-4-fluoro-benzylamino)-cyclopentanecarboxylic acid methyl ester (256 mg, 0.898 mmol, 70% as a yellow oil, containing residual ethyl acetate. 1H NMR (400 MHz, CDCl3) δ: 1.55-1.97 (m, 6H), 2.86 (dd, 1H, J1=14.2 Hz, J2=7.0 Hz), 3.19 (dd, 1H, J1=13.1 Hz, J2=6.9 Hz), 3.62 (s, 3H), 3.64 (d, 2H, J=6.2 Hz), 6.96 (t, 1H, J=8.5 Hz), 7.04-7.08 (m, 1H), 7.26-7.28 (m, 1H). LC-MS (ESI) calcd for C14H17ClFNO2 285.09, found 286.0 [M+H+].

Provenance & Evidence