4-Nitrobenzyl chloroformate → HCID 86751996, compound

Participants

Reaction Conditions

Reaction Steps

230 mg of diisopropylethylamine were added to a suspension of 1.0 g of (2S,4S)-4-(4-methoxybenzylthio)-2-[(3S)-pyrrolidin-3-ylaminocarbonyl]-1-(4-nitrobenzyloxycarbonyl)pyrrolidine hydrochloride [prepared as described in step (ii) above] and 240 mg of 4-dimethylaminopyridine in 10 ml of dry acetonitrile, and the resulting mixture was cooled to 0° C. A solution of 430 mg of 4-nitrobenzyl chloroformate in 4 ml of dry acetonitrile was then added to the mixture. The mixture was then stirred at room temperature for 3 hours, after which a solution of 117 mg of 4-nitrobenzyl chloroformate in 2 ml of dry acetonitrile was added and the mixture was stirred at the same temperature for 1 hour. At the end of this time, the reaction mixture was freed from the solvent by distillation under reduced pressure, and the residue was diluted with 50 ml of methylene chloride. The diluted solution was washed with a saturated aqueous solution of sodium chloride. The aqueous washings were extracted with methylene chloride. The organic extract and the methylene chloride solution were combined and dried over anhydrous magnesium sulfate, and then the solvent was removed by distillation under reduced pressure. The resulting residue was purified by column chromatography through silica gel, using a 4:1 by volume mixture of methylene chloride and acetonitrile as the eluent, to give 862 mg of the title compound as a powder.

Provenance & Evidence