2-Ethoxy-2-hydroxyacetic acid p-nitrobenzyl ester → 2-[(3S,4R)-4-acetylthio-3-methoxy-2-oxoazetidin-1-yl]-2-hydroxyacetic acid p-nitrobenzyl ester

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Reaction Steps

1.15 g of 2-ethoxy-2-hydroxyacetic acid p-nitrobenzyl ester and 4 g of molecular sieves A4 are added to a solution of 350 mg of (3S,4R)-4-acetylthio-3-methoxy-2-oxoazetidine in a mixture of 24 ml of absolute toluene and 6 ml of absolute dimethylformamide and the mixture is stirred overnight at room temperature under nitrogen. The molecular sieves are filtered off and the filtrate is concentrated by evaporation in vacuo. The residue is chromatographed over silica gel, and the title compound is obtained by eluting with toluene and toluene/ethyl acetate (19:1).

Provenance & Evidence