Hydrochloric Acid → 1-(tert-Butoxycarbonyl)-4-piperidinecarboxylic acid

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Reaction Steps

A solution of isonipecotic acid (18) (2.6 g, 20 mmol) in 1,4-dioxane/H2O (3:2, 100 mL) was treated with NaHCO3 (8.4 g, 100 mmol, 20 mL H2O), followed by t-Boc2O (4.8 g, 22 mmol) at room temperature. After stirring for 3 h, the solution was acidified with 1 N HCl (50 mL), extracted with EtOAc (3×100 mL). The combined organic extracts were washed with saturated solution of NaHCO3 (50 mL), brine (50 mL), dried over MgSO4 and concentrated to give a white solid (19) (4.16 g, 91%). 1H NMR (500 MHz, CDCl3) δ 4.02 (br s, 2H), 2.86 (t, J=12.0 Hz, 2H), 2.50 (tt, J=11.0, 4.0 Hz, 1H), 1.91 (dd, J=13.0, 2.5 Hz, 2H), 1.65 (m, 2H), 1.46 (s, 9H), MS (ESI−) m/z 228.65 (M−H−).

Provenance & Evidence