Hydrochloric Acid → 2-Ethoxy-3-(2,2,2-trifluoro-acetylamino)-pyrrolidine-1-carboxylic acid benzyl ester

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Reaction Steps

To Intermediate 4 (34 g) in ethanol (1070 ml) at −5° C. was added sodium borohydride (9.86 g). A solution of 4M hydrogen chloride in 1,4-dioxan (20 ml) was then added dropwise. Periodically further portions of 4M hydrogen chloride in 1,4-dioxan (2×5 ml, 1×10 ml) and sodium borohydride (2 g) were added. After 3 h, concentrated sulphuric acid (11 ml) was added and the mixture warmed to room temperature for 2 h. Saturated aqueous sodium bicarbonate (300 ml) was then added and the ethanol and dioxan removed in vacuo. The residue was diluted with water (500 ml) and extracted with ethyl acetate (3×500 ml). The combined extracts were washed with brine and dried (MgSO4). The solvent was removed in vacuo and the residue purified by flash chromatography on silica gel 9385 eluting with ether, to give the title compound (21 g). Mass spec. MNH4+ (found) 378 MNH4+ (calculated) 378

Provenance & Evidence