Ammonia → BOC-Norleucine Amide

Participants

Reaction Steps

To a stirred solution of N-Boc-L-Nle-OH (0.5 g, 2.2 mmol) in anhydrous THF (15 mL) under Ar at -23° C. was added 4-methylmorpholine followed by iso-butyl chloroformate (0.21 mL, 2.2 mmol). The reaction mixture was then treated with gaseous NH3 for 1 h. Stirring was continued at -23° C. for an additional 2 h. The mixture was warmed to R.T. and then poured onto 10% aqueous citric acid (20 mL). The mixture was extracted with EA (3×50 mL). The combined organics were washed with sat. NaHCO3 (3×25 mL), sat. NaCl (2×25 mL), dried (MgSO4), filtered and concentrated to afford N-Boc-L-Nle-NH2 as a white solid (0.48 g, 91%): 1H NMR (CDCl3, 300 MHz) δ 0.84-0.92 (m, 3H), 1.22-1.31 (m, 4H), 1.41 (s, 9H), 1.49-1.59 (m, 1H), 1.74-2.01 (m, 1H), 4.03-4.1 (m, 1H), 5.06 (d, 1H), 5.75 (s, 1H), 6.25 (s, 1H) ppm.

Provenance & Evidence