N-Phthaloylglycine → 2-[(3-Ethyl-1,2,4-oxadiazol-5-yl)methyl]-1H-isoindole-1,3(2H)-dione

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Reaction Steps

At 40° C., a suspension of 26.0 g of carbonyldiimidazole in 250 ml of THF is added to a solution of 65.7 g of phthalimidoacetic acid in 500 ml of THF (absolute). After about one hour, no release of gas can be observed any longer. At this point in time, a solution of 28.2 g of propionamidoxime in 50 ml of THF-- is added, and the mixture is stirred at room temperature for 24 hours. After the precipitate has been filtered off, the filtrate is concentrated under vacuum and, after addition of 500 ml of dry xylene, is heated under reflux for 6 hours on a water trap. The still hot solution is separated from the oily residue and concentrated under vacuum. Crystallization from EtOH yields 31.5 g (76.5%, based on carbonyldiimidazole) of oxadiazole having a melting point of 106°-107° C.

Provenance & Evidence