4-Methylmorpholine → 1-[2-(4-Fluoro-3-trifluoromethyl-phenyl)-2-oxo-ethylcarbamoyl]-piperidine-4-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

Add N-methylmorpholine (3 equiv; 631.52 mmoles; 69.66 mL) to a solution of piperidine-1,4-dicarboxylic acid mono-tert-butyl ester (1.20 equiv; 252.61 mmoles; 57.92 g) in tetrahydrofuran (THF) (400 mL). Cool the mixture to −10° C. with a dry ice-acetone bath. Add isobutyl chloroformate (1.1 equiv; 231.56 mmoles; 30.26 mL) dropwise while maintaining the temperature below −5° C. After 30 min at −5°-10° C., add 2-amino-1-(4-fluoro-3-trifluoromethyl-phenyl)-ethanone hydrochloride (54.23 g; 1.00 equiv; 210.51 mmoles) suspended in THF (300 mL) and stir the mixture in the bath at −5° C. for 20 min. Stir for 1 hour at RT. Add water and EtOAc, then wash the organic layer with water and saturated aqueous sodium chloride. Dry over MgSO4, filter and remove solvent in vacuo. Suspend the crude in MTBE and stir for 2 hours. Filter the solid and dry in vacuo to give 1-[2-(4-Fluoro-3-trifluoromethyl-phenyl)-2-oxo-ethylcarbamoyl]-piperidine-4-carboxylic acid tert-butyl ester (64.44 g; 70.79% yield).

Provenance & Evidence