Citric Acid → 1-[6-(2-t-Butylsulfamoylphenyl)pyridin-3-ylmethyl]-5-propyl-1H-pyrazole-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

To a suspension of N-t-butyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-benzenesulfonamide (722 mg, 2.1 mmol) and 1-(6-bromopyridin-3-ylmethyl)-5-propyl-1H-pyrazole-3-carboxylic acid ethyl ester (500 mg, 1.4 mmol) in toluene (4.0 mL, 37 mmol) was added a solution of potassium carbonate (392 mg, 2.84 mmol) in water (530 μL, 30 mmol). The resulting solution was sparged shortly with nitrogen before tetrakis(triphenylphosphine)-palladium(0) (328 mg, 284 μmol) was added. The mixture heated in the microwave at 100° C. for 30 minutes, then cooled to room temperature. Aqueous 1% citric acid was added, the mixture was extracted with EtOAc. The combined organics were partially concentrated, filtered through Celite® (EtOAc rinse), and concentrated. The crude residue was diluted with t-butyl alcohol (21.6 mL, 226 mmol), and 0.20 M LiOH in water (42.6 mL, 8.5 mmol) was added. The mixture was stirred overnight, then concentrated and extracted with EtOAc. The EtOAc was back-extracted with 1 N LiOH. The combined aqueous layers were acidified with 1 N HCl to pH 4-5. The acidic aqueous layer was extracted with EtOAc and DCM to yield 1-[6-(2-t-butylsulfamoylphenyl)pyridin-3-ylmethyl]-5-propyl-1H-pyrazole-3-carboxylic acid (630 mg).

Provenance & Evidence