A mixture of ethyl piperidine-4-carboxylate (90 mg, 0.57 mmol) and N-ethyl-N-isopropylpropan-2-amine (99 μL, 0.57 mmol) in DMF (342 μL) were treated with a solution of 2-(4′-(6-carbamoyl-3,5-dimethylpyrazin-2-yl)-2-chlorobiphenyl-4-yl)acetic acid (Example 1; 205 mg, 0.52 mmol), 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (124 mg, 0.65 mmol), 1H-benzo[d][1,2,3]triazol-1-ol (70.0 mg, 0.52 mmol) and N-ethyl-N-isopropylpropan-2-amine (99 μL, 0.57 mmol) in DMF (2049 μL) at RT. The resulting solution was stirred at RT for 20 hours. The reaction mixture was evaporated to dryness and redissolved in DCM (5 mL), and washed with water (5 mL). The organic layer was evaporated to afford ethyl 1-(2-(4′-(6-carbamoyl-3,5-dimethylpyrazin-2-yl)-2-chlorobiphenyl-4-yl)acetyl)piperidine-4-carboxylate (291 mg, 105%) which was used without further purification.
