Trichloroacetyl isocyanate → (2S,4S)-2-[4-(2-carbamoyloxyethyl)-1-piperazinylcarbonyl]-4-(4-methoxybenzylthio)-1-(4-nitrobenzyloxycarbonyl)pyrrolidine

Participants

Reaction Steps

1.43 ml of trichloroacetyl isocyanate were added, whilst ice-cooling, to a solution of 5.59 g of (2S,4S)-2-[4-(2-hydroxyethyl)-1-piperazinylcarbonyl]-4-(4-methoxybenzylthio)-1-(4-nitrobenzyloxycarbonyl)pyrrolidine [prepared as described in step (i) above] in 50 ml of dry methylene chloride, and the resulting mixture was stirred at the same temperature for 30 minutes. At the end of this time, the solvent was removed by distillation under reduced pressure, and the resulting residue was dissolved in 120 ml of methanol. This solution was then stirred at room temperature for 4.5 hours in the presence of 35 g of silica gel (Merck, silica gel 60, 230-400 mesh). The silica gel was removed by filtration and the filtrate was freed from the solvent. The residue was purified by column chromatography through silica gel, using a 8:1 by volume mixture of ethyl acetate and methanol as the eluent, to give 5.76 g of the title compound as a colorless powder.

Provenance & Evidence