Sodium borohydride → L-Proline 1,1-dimethylethyl ester

Participants

Reaction Steps

0.45 g (0.84 mmol) of N-[[N-[N-(benzyloxycarbonyl)-L-alanyl]-L-phenylalanyl]methyl]-L-proline tert.butyl ester, prepared as described in Example 5, was reduced in 15 ml of isopropanol in the presence of 80 mg of sodium borohydride as described in Example 7. After working-up the two isomers were separated by chromatography on silica gel using System A for the elution. There were obtained 70 mg of isomer 1 of N-[3(S)-[[N-(benzyloxycarbonyl)-L-alanyl]amino]-2(R or S)-hydroxy-4-phenylbutyl]-L-proline tert.butyl ester in the form of a gum; Rf (System A): 0.38; MS: m/e 540 [M+H]+ and 50 mg of isomer 2 in the form of a gum; Rf (System A) 0.21; MS: m/e 540 [M+H]+.

Provenance & Evidence