Hydrochloric Acid → (3S)-1-[2-(5-fluoro-1,3-dihydro-2H-isoindol-2-yl)-2-oxoethyl]-3-phenylpiperidin-2-one

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Reaction Steps

To a suspension of 2-(2-oxo-3-phenylpiperidin-1-yl)acetic acid (4.43 g, 18.99 mmol; Example 91D) and 5-fluoroisoindoline hydrochloride (3.63 g, 20.89 mmol) in dichloromethane (30 mL) was added N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine (5.04 mL, 28.5 mmol). After a few minutes, a dark brown solution resulted. The reaction was stirred overnight then poured into 1 N HCl (100 mL). The product was extracted into dichloromethane (3×100 mL). The combined extracts were washed with brine (100 mL), dried over magnesium sulfate and concentrated. The residue was dissolved in minimal dichloromethane and was loaded onto a GraceResolv™ 80 g silica gel column (Grace Davison Discovery Sciences) and the product eluted with a gradient of 5% ethyl acetate/hexanes to 100% ethyl acetate/hexanes (Flow=40 mL/minute) over 60 minutes to provide the racemic title compound. Supercritical fluid chromatography using a ChiralPak® OD-H 21×250 mm column eluting using 10% to 50% methanol/CO2 over 20 minutes gave the title compound as the first eluting enantiomer. 1H NMR (300 MHz, CDCl3) δ 7.40-7.11 (m, 6H), 6.97 (dd, J=8.6, 18.0, 2H), 4.84 (dd, J=8.7, 19.3, 4H), 4.44 (dd, J=1.6, 15.7, 1H), 4.05 (d, J=15.7, 1H), 3.81-3.47 (m, 3H), 2.34-1.83 (m, 4H); MS (ESI+) m/z 353.0 (M+H)+.

Provenance & Evidence