Chloromethyl N,N-diisopropylcarbamate (2.81 g) and 2.76 g of triethyl benzyl ammonium chloride were added to 50 ml of a solution of 4.89 g of sodium (1R,5S,6S)-6-((1R)-1-hydroxyethyl)-2-[[(Z)-2-(4-hydroxymethylthiazol-5-yl)ethen-1-yl]thio]-1-methyl-1-carbapen-2-em-3-carboxylate in N,N-dimethylacetamide, and the mixture was stirred at 30° C. for 5 hr. The reaction solution was washed twice with 180 ml of heptane. Thereafter, 125 ml of ethyl acetate and 125 ml of 20% brine were added thereto, followed by separation. The organic layer was washed three times with 125 ml of 10% brine, was dried over anhydrous magnesium sulfate, and was filtered, and ethyl acetate was removed by distillation under the reduced pressure to give 6.01 g of the title compound.
