Ammonium Acetate → HCID 178451792, compound

Participants

Reaction Conditions

Reaction Steps

Combine 1-[2-(4-fluoro-3-trifluoromethyl-phenyl)-2-oxo-ethylcarbamoyl]-piperidine-4-carboxylic acid tert-butyl ester (100 g, 231 mmoles), ammonium acetate (178.3 g; 2.31 moles, 10 eq), and methanol (1000 mL). The reactor used for this transformation is a coiled 1/16″ I.D. stainless steel tube (total internal volume of tubing in oven is 541 mol). Heat the reactor in an oven to 140° C. Control the back pressure in this tube at 250 psig by a regulator to allow super-heating of the solution above its normal boiling point. Pump the solution prepared above continuously through the heated tube under pressure at 6.01 mL/min (affording a total residence time in the heated tube of 90 minutes). As the solution exits the oven, cool it back to 20° C. in a tube-in-tube heat exchanger. Once the entire solution process through the reactor (8 hours total processing time), concentrate the resulting orange solution under vacuum at 30° C. to a total volume of 600 mL. Add acetonitrile (200 mL) and heat the solution to 50° C. Add water (700 mL) drop wise with seeding over 2 hours to crystallize the product. Cool the resulting slurry to 20° C. and filter the solid, then wash with 20% MeOH in water (2×200 mL). Dry the resulting solid under vacuum at 50° C. Re-slurry the solid in acetonitrile (200 mL) at 50° C. Cool the slurry to ambient temperature, filter the solid and wash with acetonitrile (100 mL) to afford 4-[4-(4-fluoro-3-trifluoromethyl-phenyl)-1H-imidazol-2-yl]-piperidine-1-carboxylic acid tert-butyl ester (54.43 g, 132 mmoles, 57%) as an off white solid.

Provenance & Evidence