Acetic Acid → 4-{Isobutyl-[(quinolin-3-yl)methyl]-amino}-piperidine-1-carboxylic acid tert-butyl ester

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Reaction Steps

Sodium triacetoxyborohydride (1.29 g, 6.09 mmol) is added to a stirred solution of 4-isobutylamino-piperidine-1-carboxylic acid tert-butyl ester (1.09 g, 4.29 mmol), quinoline-3-carboxaldehyde (0.68 g, 4.3 mmol), acetic acid (0.25 ml, 4.37 mmol), and 1,2-dichloroethane (15 ml). The reaction is stirred for 18 h at room temperature under nitrogen. The reaction is poured into 2N NaOH (100 ml) and extracted with ethyl acetate (100 ml×3). The ethyl acetate is dried over sodium sulfate and then the sodium sulfate is filtered off. The crude product is concentrated on a rotary evaporator and purified by flash chromatography on silica gel eluting with 15% acetone/hexanes to yield (1.02 g, 60%) of 4-{isobutyl-[(quinolin-3-yl)methyl]-amino}-piperidine-1-carboxylic acid tert-butyl ester: mass spectrum (ion spray): m/z=398.2 (M+1); 1H NMR (CDCl3): δ=8.93 (1H, d), 8.09 (1H, d), 8.02 (1H, s), 7.79 (1H, d), 7.70-7.66 (1H, m), 7.55-7.51 (1H, m), 4.16 (2H, br s), 3.79 (2H, s), 2.63-2.57 (3H, m), 2.27 (2H, d), 1.77-1.65 (3H, m), 1.52-1.48 (2H, m), 1.44 (9H, s), 0.85 (6H, d).

Provenance & Evidence