Dicyclohexylcarbodiimide → 3-[(Acetyloxy)methyl]-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid p-pivalyloxybenzyl ester

Participants

Reaction Steps

To a suspension of 6.6 mM of 3-[(acetyloxy)methyl]-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid sodium salt in 35 ml of dimethyl formamide (DMF) is added 2 equivalents of p-pivalyloxybenzyl alcohol followed by cooling to 0° C. after which 7.2 mM of dicyclohexylcarbodiimide in 7.5 ml of DMF is added dropwise with stirring. The mixture is stirred at 0° C. for 1 hour and an additional four hours at room temperature. The formed dicyclohexylurea is removed by filtration. The filtrate is diluted with chloroform, washed with water, dried over magnesium sulfate, filtered, and evaporated in vacuo to give 3-[(acetyloxy)methyl]-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid p-pivalyloxybenzyl ester.

Provenance & Evidence