A solution of 0.98 g of (2S,4S)-2-(3-dimethylaminoazetidin-1-ylcarbonyl)-4-mercapto-1-(4-nitrobenzyloxycarbonyl)pyrrolidine (prepared as described in Preparation 121) dissolved in 20 ml of dry acetonitrile and 0.418 ml of diisopropylethylamine were added dropwise at the same time, whilst ice-cooling, to a solution of 1.43 g of 4-nitrobenzyl (1R,5R,6S)-2-(diphenylphosphoryloxy)-6-[(1R)-1-hydroxyethyl]-1-methyl-1-carbapen-2-em-3-carboxylate (prepared as described in Preparation 123) in 25 ml of dry acetonitrile. The mixture was then stirred at the same temperature for 2 hours, after which it was left to stand in a refrigerator overnight. The reaction mixture was then concentrated by evaporation under reduced pressure, and the resulting residue was diluted with ethyl acetate; the resulting mixture was washed with water and then with an aqueous solution of sodium chloride. The ethyl acetate layer was dried over anhydrous magnesium sulfate and then concentrated by evaporation under reduced pressure. The residue was purified by silica gel column chromatography and the fractions obtained by elution with a 75:25 by volume mixture of ethyl acetate and methanol were combined and concentrated by evaporation under reduced pressure, to obtain 1.16 g of the title compound, as a powder.
