Trifluoroacetic acid → Z-Val-pro-OH

Participants

Reaction Conditions

Reaction Steps

Trifluoroacetic acid (200 ml) was added to a mixture of N-benzyloxycarbonyl-L-valyl-L-proline tert-butyl ester (80.0 g) in methylene chloride ((300 ml) at 0° C. over approximately 30 minutes. After stirring at 0° C. for one hour, the reaction mixture was allowed to rise to ambient temperature and stirred an additional 3 hours. The reaction mixture was then concentrated under vacuum and reconcentrated four times from toluene to remove residual trifluoroacetic acid. The resulting viscous oil was dried under vacuum for 16 hours. The crude product was purified on by chromatography on silica gel, using methylene chloride as eluant, to give N-benzyloxycarbonyl-L-valyl-L-proline (A) (63.6 g) as a pale yellow viscous oil; NHR (d6 -DMSO): 0.92(2d,6H), 1.65-2.05(2 m,4H), 2.25(m,1H), 3.60(m,1H), 3.80(m,1H), 4.05(dd,1H), 4.25(m,1H), 5.02(2d,2H), 7.35(m,5H), 7.50(d,1H).

Provenance & Evidence