Triethylamine → 2-(3,5-Difluorobenzyl)-1-(methoxycarbonyl)piperidine-4-carboxylic acid

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Reaction Steps

Dimethyl 2-(3,5-difluorobenzyl)piperidine-1,4-dicarboxylate (8.459 g, 25.84 mmol) was dissolved in acetonitrile (85 mL) and water (1.7 mL). Lithium bromide (17.95 g, 206.74 mmol) and triethylamine (14.33 mL, 103.37 mmol) were added. The suspension was heated to reflux 1.5 h before water (100 mL) and MTBE (300 mL) were added. The organic phase was extracted with water (×2). The combined water phases were acidified to pH 1 with 3.8 M HCl and extracted with MTBE (×2). The combined organic phases were washed with water, dried with MgSO4, filtered through celite and concentrated. The crude product was redissolved in MTBE and washed with 0.1 M HCl (×2) and water. The organic phase was dried with MgSO4 and concentrated to give 2-(3,5-difluorobenzyl)-1-(methoxycarbonyl)piperidine-4-carboxylic acid (6.88 g, 85%). MS m/z 314 (M+H)+

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