Propylene Oxide → (3R,4R)-3-[2-(2-chloroacetamidothiazol-4-yl)-2-methoxyiminoacetamido]-4-methylsulfonyl-2-oxoazetidine

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Reaction Steps

To a solution of 0.122 g of DMF in 5 ml of methylene chloride is added 0.10 ml of diphosgene at -10° C. The mixture is stirred for 30 minutes at room temperature, then cooled to a temperature of -70° C., followed by dropwise addition of 10 ml of methylene chloride solution containing 0.427 g of 2-(2-chloroacetamidothiazol-4-yl)-2-methoxyiminoacetic acid and 0.17 g of triethylamine. The mixture is stirred for 2 hours at a temperature ranging from -25° to -20° C., which is cooled to a temperature of -70° C., to which are added 0.17 g of triethylamine, a solution of 0.229 g of (3R,4R)-3-amino-4-methylsulfonyl-2-oxoazetidine in 3 ml of DMA, and 2 ml of propylene oxide, successively. The temperature of the mixture is raised up to room temperature in the course of 1.5 hours. The reaction mixture is concentrated under reduced pressure, and the residue is purified on a silica-gel column (ethyl acetate:n-hexane=1:1) to give 0.415 g of (3R,4R)-3-[2-(2-chloroacetamidothiazol-4-yl)-2-methoxyiminoacetamido]-4-methylsulfonyl-2-oxoazetidine. This is in agreement with the compound (syn-isomer) obtained in Reference Example 15B in IR and NMR.

Provenance & Evidence