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) □ 1.04 (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