Isobutyl iodide → tert-butyl[(3S,5S)-5-(2-fluorophenyl)-1-(2-methylpropyl)-2-oxopiperidin-3-yl]carbamate

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Reaction Conditions

Reaction Steps

To a pre-cooled 0° C. solution of tert-butyl [(3S,5S)-5-(2-fluorophenyl)-2-oxopiperidin-3-yl]carbamate (0.85 g, 2.76 mmol) in tetrahydrofuran:N-methyl-2-pyrrolidinone (2:1, 18 mL) was added lithium bis(trimethylsilyl)amide (3.58 mL, 3.58 mmol, 1 M in THF) and the mixture was stirred at 0° C. for 30 min. 1-Iodo-2-methylpropane (0.48 mL, 4.13 mmol) was added and the resulting mixture was stirred at 0° C. for 2 h and then warmed to 23° C. and stirred for an additional 18 h. The mixture was diluted with water and extracted with ethyl acetate (3×). The combined organic extracts were washed with water, brine, dried over sodium sulfate, filtered and concentrated. Purification by silica gel chromatography (0% ethyl acetate→70% ethyl acetate/hexane) was followed by separation of the cis/trans diastereomers using supercritical fluid chromatography with a ChiralPak® AD column and eluting with 20% ethanol in carbon dioxide to afford the title compound as the second diastereomer to elute. MS: m/z=387.2 (M+Na).

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