Acetonitrile → (2S,5R)-methyl 6-(benzyloxy)-7-oxo-1,6-diazabicyclo[3.2.1]octane-2-carboxylate

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Reaction Conditions

Reaction Steps

To (2S,5R)-methyl 5-(benzyloxyamino)piperidine-2-carboxylate (1.154 g, 4.37 mmol) was added dehydrated acetonitrile (198 mL), followed by ice-cooling. Triethylamine (1.60 mL) and diphosgene (0.389 mL) were sequentially added dropwise at 5° C. or less, followed by stirring at 2° C. for 20 minutes. Then, to the reaction solution was added 4-dimethylaminopyridine (70.0 mg), followed by stirring at room temperature for 10 hours. The reaction solution was concentrated under reduced pressure, followed by substituting and concentrating with ethyl acetate three times, and the solution was concentrated to 30 mL. Ethyl acetate (20 mL) and water (40 mL) were added thereto, followed by liquid separation, and the separated aqueous layer was extracted with ethyl acetate (30 mL) twice. The combined organic layers were washed with 5% citric acid aqueous solution (40 mL), 6.5% sodium bicarbonate aqueous solution (30 mL), and 5% brine (30 mL), and dried over anhydrous sodium sulfate, followed by filtration and concentration under reduced pressure. 1.16 g of the resulting residue was diluted with ethyl acetate (5.5 mL), and n-hexane (11 mL) was added, and a seed crystal was inoculated for crystallization. Further, n-hexane (49 mL) was added, followed by stirring at 0° C. for 1 hour. Subsequently, crystals were filtered, washed with n-hexane (60 mL), and then dried under vacuum to afford 882.3 mg of the title compound as colorless crystalline powder (yield 71%).

Provenance & Evidence