4-Nitrobenzyl chloroformate → (2S, 4S)-4-(4-Methoxybenzylthio)-2-[3-(4-nitrobenzyloxycarbonylamino)azetidin-1-ylcarbonyl]-1-(4-nitrobenzyloxycarbonyl)pyrrolidine

Participants

Reaction Steps

0.81 g of (2S,4S)-2-(3-aminoazetidin-1-ylcarbonyl)-4-(4-methoxybenzylthio)-1-(4-nitrobenzyloxycarbonyl)pyrrolidine [prepared as described in step (a) above] was dissolved in 20 ml of methylene chloride, and 0.32 g of diisopropylethylamine and 0.40 g of p-nitrobenzyl chloroformate were added to the resulting solution, whilst ice-cooling. The resulting mixture was then stirred at the same temperature for 40 minutes. At the end of this time, the reaction mixture 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 9385, manufactured by Merck, 40 g) to give 0.64 g of the title compound, in the form of an amorphous powder, from the fraction obtained by solution with a 99:1 by volume mixture of ethyl acetate and methanol.

Provenance & Evidence