Pyridine → Tert-butyl 4-(3-(dimethylcarbamoyloxy)phenylcarbamoyl)-4-(2-methoxyethoxy)piperidine-1-carboxylate

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Reaction Steps

To a solution of carboxylic acids from step B, pyridine (0.2 mL, 2.48 mmol), and DMF (catalytic, 2 drops) in CH2Cl2 (3.1 mL) was added dropwise oxalyl chloride (60 μL, 0.68 mmol, caution: exothermic). After gas evolution subsided, the reaction was stirred at ambient temperature for 30 minutes. 3-Aminophenyl dimethylcarbamate (112 mg, 0.62 mmol) was added in one portion to this solution, which was stirred for another 30 minutes. The reaction was quenched with saturated aq. NH4Cl, and the aqueous layer was extracted with ethyl acetate (3×50 mL). The combined organic layers were washed with brine, dried with MgSO4, filtered, and concentrated under vacuum. Silica gel chromatography (80% ethyl acetate:hexanes) afforded the title compound as an off-white solid (150 mg). MS (ES+) [M+CH3CN]+=529.3.

Provenance & Evidence