Triethylamine → 2-(4-Nitro-phenyl)-morpholine-4-carboxylic acid tert-butyl ester

Participants

Reaction Steps

To an ice-cold stirred mixture of (2-hydroxyethyl)-[2-hydroxy-2-(4-nitro-phenyl)-ethyl]-carbamic acid tert-butyl ester (5.50 g, 16.8 mmol) and triphenylphosphine (5.17 g, (19.7 mmol) in toluene (80 mL) was added triethylamine (6.15 mL, 4.46 g, 44.2 mmol) followed a solution of di-tert-butylazodicarboxylate (3.10 mL, 19.7 mmol) in toluene (30 mL) dropwise. The reaction mixture was stirred for 18 h at room temperature, washed with water (50 mL), and the aqueous layer was back extracted with ethyl acetate (2×50 mL). The combined organic layers were dried over sodium sulfate, filtered and evaporated. The residue was purified by column chromatography eluting with dichloromethane, the obtained product was triturated with diisopropyl ether and collected. The title compound (3.56 g, 11.5 mmol, 68%) was obtained as a white solid. ESMS m/z 253 (M+H-tBu)+; 1H NMR (400 MHz, CDCl3) δ ppm 8.23 (d, J=8.3 Hz, 2H) 7.57 (d, J=8.3 Hz, 2H) 4.53 (d, J=10.3 Hz, 1H) 4.20 (br. s., 1H) 4.06 (d, J=11.3 Hz, 1H) 3.94 (br. s., 1H) 3.66-3.75 (m, 1H) 3.06 (br. s., 1H) 2.76 (br. s., 1H) 1.50 (s, 9H).

Provenance & Evidence