(2S,4S)-4-(4-methoxybenzyl)thio-1-(4-nitrobenzyloxycarbonyl)-L-proline → HCID 10580921, compound

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Reaction Steps

860 mg of (2S,4S)-4-(4-methoxybenzylthio)-1-(4-nitrobenzyloxycarbonyl)-2-pyrrolidinecarboxylic acid [prepared as described in Preparation 1(b)] were dissolved in 8 ml of anhydrous acetonitrile, and 410 mg of N,N'-carbonyldiimidazole were added to the resulting solution. The resulting mixture was then stirred at room temperature for 30 minutes, after which a solution of 1250 mg of 4-[2-(4-nitrobenzyloxycarbonyl)oxyethyl]homopiperazine bis(trifluoroacetate) in 5 ml of acetonitrile and 860 μl of diisopropylethylamine were added, in that order. The resulting mixture was then stirred at room temperature for 35 hours. At the end of this time, the reaction mixture was diluted with 100 ml of ethyl acetate and washed with an aqueous solution of sodium hydrogencarbonate and with an aqueous solution of sodium chloride, in that order. The organic layer was then dried over anhydrous sodium sulfate and concentrated by evaporation under reduced pressure. The residue was subjected to column chromatography through silica gel using mixtures of ethyl acetate and methanol ranging from 98:2 to 95:5 by volume as the eluent. Those fractions containing the title compound were collected and concentrated by evaporation under reduced pressure, to afford 900 mg of the title compound.

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