Proton sponge → tert-butyl (2S)-2-{(1R,2R)-1-methoxy-2-methyl-3-[(4R,5S)-4-methyl-2-oxo-5-phenyl-1,3-oxazolidin-3-yl]-3-oxopropyl}pyrrolidine-1-carboxylate

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Reaction Steps

Following a literature method (Diem, M. J.; Burow, D. F.; Fry, J. L. Journal of Organic Chemistry 42(10), 1977, 1801-1802), to a solution of tert-butyl (2S)-2-{(1R,2R)-1-hydroxy-2-methyl-3-[(4R,5S)-4-methyl-2-oxo-5-phenyl-1,3-oxazolidin-3-yl]-3-oxopropyl}pyrrolidine-1-carboxylate (0.70 g, 1.6 mmol, from Reference Example 5) in anhydrous dichloromethane (5 mL) is added N,N,N′,N′-tetramethyl-1,8-naphthalenediamine (0.62 g, 2.9 mmol), followed by trimethyloxonium tetrafluoroborate (0.35 g, 2.4 mmol). The resulting reaction mixture is stirred for 24 hours at room temperature, quenched by the addition of ice water (25 mL), and then filtered through a diatomaceous earth pad. The filtrate is evaporated under reduced pressure and then partitioned between diethyl ether and water. The aqueous phase is extracted thrice with diethyl ether. The combined organic extracts are washed with 1M aqueous potassium bisulfate solution, water, saturated aqueous sodium bicarbonate solution, and saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to give 0.69 g (97%) of tert-butyl (2S)-2-{(1R,2R)-1-methoxy-2-methyl-3-[(4R,5S)-4-methyl-2-oxo-5-phenyl-1,3-oxazolidin-3-yl]-3-oxopropyl}pyrrolidine-1-carboxylate as a foam.

Provenance & Evidence