1,2-Dichloroethane → HCID 54414223, compound

Participants

Reaction Conditions

Reaction Steps

A solution of 4,4-difluoro-pyrrolidine-1,2-dicarboxylic acid-1-benzyl ester-2-tert-butyl ester (113) (Karanewsky, et. al., J. Med. Chem. 33, pp. 1459-1469 (1990)) (0.42 g, 1.23 mmol) and 10% palladium on carbon (0.22 g) in methanol (6 mL) was stirred at 1 atm hydrogen pressure for 3 h. The mixture was filtered through Celite and evaporated. The residue was dissolved in CH2Cl2 (4 mL) and DMF (2 mL) and cooled to 0° C. 2-Benzyloxycarbonylamino-propionic acid (0.30 g, 1.35 mmol), EDC (0.30, 1.54 mmol), DIEA (0.65 mL) and HOBt (0.17 g, 1.23 mmol) was-added and the reaction was stirred 0.5 h at 0° C., then 16 h at room temperature under nitrogen. The solvent was removed in vacuo and the residue was dissolved in ethyl acetate, then was washed with 10% sodium bisulfate, saturated sodium bicarbonate, water and brine, was dried over sodium sulfate and was evaporated. Purification by flash chromatography on silica, eluted with 25:75 ethyl acetate: hexanes provided 1-(2-benzyloxycarbonylamino-propionyl)-4,4-difluoro-pyrrolidine-2-carboxylic acid tert-butyl ester (0.39 g, 77% yield) as a colorless oil. 1H-NMR (500 MHz, CDCl3) δ 1.3-1.6 (m, 12H), 2.5 (m, 0.8H), 2.7 (m, 1.2H), 3.9 (m, 1H), 4.1 (m, 1H), 4.4 (m, 1H), 4.7 (m, 1H), 5.1 (m, 2H), 5.59 (br d, J=7.7 Hz, 0.8H), 5.7 (br d, J=7.7 Hz, 0.2H), 7.35 (m, 5H) ppm. Analytical HPLC (cyano column) 17.069 min. LC-MS (ES+): m/e=413 (M+H), 357 (M+H-tert-butyl), 313 [M+H-(CO2tert-butyl)].

Provenance & Evidence