1,2-Dichloroethane → 1-(2-Benzyloxycarbonylamino-3,3-dimethyl-butyryl)-pyrrolidine-2-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 2 (6.01 g, 2.0 mmol) in CH2Cl2 (30 ml) and anhydrous DMF (dimethylformamide)(10 ml) at 0° C. was added HOBT (3.16 g, 2.0 mmol), EDC (1-(3-dimethylaminopropyl-3-ethyl-carbodiimide hydrochloride) (7.19 g, 4.0 mmol) and L-proline-tert-butyl ester (4.22 g, 2.0 mmol). The solution was stirred at 0° C. for 10 minutes, then at room temperature for 5 hours. The solvents were evaporated in-vacuo and the resulting oil dissolved in EtOAc which was washed with H2O (3×200 ml) and brine (200 ml). The organic phase was dried over anhydrous Na2SO4, filtered and evaporated to give the crude product. Flash chromatography on silica gel using hexanes/EtOAc (95/5 to 80/20%) afforded the title compound as a colorless oil (8.30 g, 87.5% yield): 1H-NMR (500 MHz, CDCl3) δ1.04 (s, 9H), 1.45 (s, 9H), 1.89–1.96 (m, 2H), 2.02–2.05 (m, 1H), 2.18–2.22 (m, 1H), 3.65–3.69 (m, 1H), 3.79–3.82 (m, 1H), 4.34–4.37 (m, 2H), 5.03–5.19 (m, 2H), 5.53 (d, 1H), 7.26–7.38 (5H).

Provenance & Evidence