Ammonia → Avibactam Impurity 19

Participants

Reaction Conditions

Reaction Steps

230 mg (0.84 mmol) of (2R,5S)-6-(benzyloxy)-7-oxo-1,6-diazabicyclo[3.2.1]octane-2-carboxylic acid was dissolved in dehydrated dichloromethane (4.2 mL), and 110 mg of triethylamine was added, followed by cooling to 0° C. 137 mg of isobutyl chloroformate was added to the mixture, followed by stirring at the same temperature for 20 minutes. 0.6 mL of aqueous ammonia was added to the reaction mixture, followed by stirring at room temperature for 1 hour. Subsequently, water (10 mL) was added and the organic layer was aliquoted, followed by sequential washing with water and saturated brine and drying over anhydrous magnesium sulfate. The residue resulting from concentration of the solvent under reduced pressure was applied to silica gel column chromatography (hexane/ethyl acetate=1/3), and subsequently crystallized with chloroform/hexane=1:3 to afford 202 mg of the title compound as a colorless crystalline powder (yield 87%). Enantiomeric excess: 99.9% ee or more (CHIRALPAK AD-H, 4.6×150 mm, hexane/ethanol=4/1, UV 210 nm, flow rate 1 mL/min., retention time 10.3 min.).

Provenance & Evidence