Diisopropylethylamine → (2S,4S)-2-(3-Aminoazetidin-1-ylcarbonyl)-4-(4-methoxybenzylthio)-1-(4-nitrobenzyloxycarbonyl)pyrrolidine

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Reaction Steps

2.05 g of (2S,4S)-4-(4-methoxybenzylthio)-1-(4-nitrobenzyloxycarbonyl)-2-pyrrolidine carboxylic acid were dissolved in 20 ml of dry acetonitrile, and 0.78 g of N,N'-carbonyldiimidazole was added to the resulting solution, after which the mixture was stirred at for 1 hour. The resulting mixture was then added dropwise to a solution of 1.00 g of 3-aminoazetidine dihydrochloride and 2.40 ml of diisopropylethylamine in 10 ml of methanol, whilst ice-cooling, and the mixture was stirred at the same temperature for 1 hour. At the end of this time, the reaction mixture was filtered, and the filtrate was concentrated by evaporation under reduced pressure. The resulting residue was diluted with ethyl acetate and washed with water and with an aqueous solution of sodium chloride, in that order. The ethyl acetate layer was dried over anhydrous magnesium sulfate and concentrated by evaporation under reduced pressure. The residue was subjected to silica gel column chromatography (silica gel 60 9383, manufactured by Merck, 100 g) to give 2.56 g of the title compound, in the form of an amorphous powder, from the fraction obtained by elution with a 65:35 by volume mixture of ethyl acetate and methanol.

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