4-((S)-2-tert-Butoxycarbonylamino-pent-4-enoyl)-piperazine-1-carboxylic acid ethyl ester → 4-((S)-2-Benzyloxycarbonylamino-pent-4-enoyl)-piperazine-1-carboxylic acid ethyl ester

Participants

Reaction Steps

A solution of 767 mg 4-((S)-2-tert-Butoxycarbonylamino-pent-4-enoyl)-piperazine-1-carboxylic acid ethyl ester in 5 ml dichloromethane and 1.6 ml TFA was stirred for 2 h. The reaction mixture was concentrated, the residue dissolved in 4 ml dioxane/water (1:1) and 661 mg NaHCO3 and 688 mg N-(Benzyloxycarbonyloxy)succinimide were added. After 12 h the reaction mixture was diluted with ethyl acetate and washed with water, 0.1 M HCl and half-saturated aqueous NaHCO3 solution. The crude product obtained after evaporation of the solvent was purified by chromatography on silica using ethyl acetate/heptane 1:2 to 2:1 as eluent. Yield: 640 mg.

Provenance & Evidence