Water → tert-Butyl [(6S,8S)-6-(2,3-difluorophenyl)-3-(2,2,2-trifluoroethyl)-5,6,7,8-tetrahydroimidazo[1,2-a]pyridin-8-yl]carbamate

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Reaction Conditions

Reaction Steps

To a solution of crude tert-butyl {(3S,5S)-5-(2,3-difluorophenyl)-2-[(4,4,4-trifluoro-2-hydroxybutyl)imino]piperidin-3-yl}carbamate (99.0 mg, 0.219 mmol) in acetonitrile (2.19 mL) was added pyridinium dichromate (247 mg, 0.657 mmol), and the mixture was stirred 2.5 h at 60° C. Pyridinium dichromate (392 mg, 1.04 mmol) was added and the resulting mixture stirred 72 h at 60° C. Pyridinium dichromate (300 mg, 0.797 mmol) was added and the resulting mixture stirred 4 h at 60° C. The mixture was cooled to ambient temperature and saturated aqueous sodium bicarbonate was added. Water was added, and the mixture was extracted with ethyl acetate (3×). The combined organic extracts were washed with brine, dried over magnesium sulfate, filtered and concentrated. Purification by reverse phase chromatography (C-18, 95% water/acetonitrile→15% water/acetonitrile with 0.1% trifluoroacetic acid) gave the title compound (59 mg). MS 432.2 (M+1).

Provenance & Evidence