To a suspension of 6-aminopicolinic acid (33 mg, 0.24 mmol) in DMF (2 mL) was added EDC (45.9 mg, 0.24 mmol), HOBt (32.3 mg, 0.24 mmol). The mixture was stirred at rt for 0.5 h, then was added DIPEA (0.083 mL, 0.48 mmol) and (R)-2-amino-1-((S)-4-(4-chlorophenyl)-4-hydroxy-3,3-dimethylpiperidin-1-yl)-3-methylbutan-1-one hydrochloride (90 mg, 0.239 mmol). The mixture was stirred at rt overnight. The reaction was quenched with NaHCO3 (aq) and stirred at rt for 1 h, extracted by EtOAc, washed with brine and dried over Na2SO4. After concentrating in vacuo, the residue was triturated with CH2Cl2 and filtered to give a yellow solid as 6-amino-N—((R)-1-((S)-4-(4-chlorophenyl)-4-hydroxy-3,3-dimethylpiperidin-1-yl)-3-methyl-1-oxobutan-2-yl)picolinamide (86 mg, 0.187 mmol, 78% yield).
