Ammonium Acetate → 4-[1-Hydroxy-5-(2-fluoropyridin-4-yl)-4-(3-trifluoromethylphenyl)-1H-imidazol-2-yl]piperidine-1-carboxylic acid benzyl ester

Participants

Reaction Conditions

Reaction Steps

To a mixture of 1-(2-fluoropyridin-4-yl)-2-(3-trifluoromethylphenyl)ethane-1,2-dione-1-oxime (11.4 g, 0.037 mole) and N-benzyloxycarbonylpiperidin-4-carboxaldehyde [Amici et al Eur. J. Med. Chem. 26, 625-631 (1991)] (9.93 g, 0.040 mol), in acetic acid (250 mL) was added ammonium acetate (56.29 g, 0.730 mole). The mixture was heated to 75° C. for 1H, cooled and concentrated to remove most of the acetic acid. The residue was poured into concentrated NH4OH (100 mL), ice (200 g) and methylene chloride (800 mL) and the pH adjusted to 8 with NH4OH. The methylene chloride layer was removed and the aqueous layer washed with methylene chloride (2×300 mL). The combined organic phases were washed with water (300 mL), brine (300 mL), dried over anhydrous sodium sulfate, filtered and concentrated to give an oil used in the next step without further purification.

Provenance & Evidence