Dimethyl Sulfoxide → tert-Butyl 1-oxa-6-azaspiro(2.5)octane-6-carboxylate

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Reaction Conditions

Reaction Steps

A stirred solution of 60% aqueous sodium hydroxide solution (117 mg, 2.92 mmol) in dimethyl sulfoxide (2 ml) was added with trimethyl sulfoxinium iodide (627 mg, 2.79 mmol) under a nitrogen atmosphere. The mixture was stirred for 45 minutes in ice-water bath, added slowly with 4-oxo-piperidine-1-carboxylic acid tert-butyl ester (500 mg, 2.5 mmol) while maintaining the temperature below 10° C. Upon completion of the addition, the mixture was stirred for 5 minutes in the ice-water bath and stirred for another 2 hours at 25° C. in an oil bath. The resulting mixture was added with cold water (20 ml) and extracted with ethyl ether (20 ml×3). The combined organic extracts were dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give 1-oxa-6-aza-spiro[2.5]octane-6-carboxylic acid tert-butyl ester (479 mg, 85.5%) as a white solid.

Provenance & Evidence