Trifluoroacetic acid → 4-Morpholinopiperidine

Participants

Reaction Steps

To a stirred solution of 4-oxo-piperidine-1-carboxylic acid tert-butyl ester (Aldrich, 3.0 g, 15 mmol) in THF (25 mL), morpholine (Aldrich, 1.56 g, 18 mmol) and Ti(OiPr)4 (Aldrich, 5.58 mL) were added successively and the mixture was stirred at room temperature for 1 hour. Then, 15 mL of ethanol was added and followed by sodium cyanoborohydride (0.63 g, 10.05 mmol). The resulting mixture was stirred at room temperature over night and the reaction was quenched with addition of water (4 mL). The mixture was stirred for 30 minutes and the white solid was filtered out and the filtrate was evaporated. The residue was partitioned between ether and water and the organic layer was separated and dried with sodium sulfate. Removal of solvent gave a white solid which was treated with 40 mL of 50% TFA in methylene chloride. The solution was stirred at room temperature for 1 hour and the solvent was removed. The residue was lyophilized to give a white solid. 5.48 g, 98%. MS (m+H)+: 171.

Provenance & Evidence