Methyl chloroformate → 1-Piperidinecarboxylic acid, 3-[(R)-(3-chlorophenyl)[2-[(methoxycarbonyl)amino]ethoxy]methyl]-, 1,1-dimethylethyl ester, (3R)-

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Reaction Conditions

Reaction Steps

To a solution of (R)-tert-butyl 3-((R)-(2-aminoethoxy)(3-chlorophenyl)methyl)piperidine-1-carboxylate (7.7 g, 21 mmol) and DMAP (1.27 g, 10 mmol, 0.5 eq) in dry CH2Cl2 (120 mL), Et3N (6.38 g, 8.45 mL, 63 mmol) was added. The resulting mixture was cooled to 0-5° C. under ice-water bath, a solution of methyl chloroformate (9.88 g, 8.1 mL, 104.5 mmol, 5 eq) in dry CH2Cl2 (50 mL) was added dropwise. After addition, the reaction mixture was stirred for 1-2 hr at 0-5° C. The reaction was quenched with water (80 mL). The aqueous layer was extracted with CH2Cl2 (3×50 mL), the combined organic layers were washed with 10% citric acid (2×80 mL) and brine, then dried over Na2SO4, filtered and concentrated to the crude product, which was purified by preparative HPLC to afford (R)-tert-butyl 3-((R)-(3-chlorophenyl)(2-(methoxycarbonylamino)ethoxy)methyl)piperidine-1-carboxylate (4.4 g, the total yield for five steps is 41%).

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