To a solution of 6-tert-butylnicotinic acid (23.5 mg, 131 μmol) and 2-((R)-3-amino-piperidin-1-yl)-5-(pyridin-2-ylamino)-thiazole-4-carboxylic acid amide (38 mg, 119 μmol) in N,N-dimethylformamide (1 mL) was added diisopropylethylamine (35 μL, 200 μmol) followed by 0-(benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (61 mg, 161 μmol). After stirring at ambient temperature overnight under an atmosphere of argon the reaction was quenched by the addition of saturated aqueous ammonium chloride (2 mL), the mixture poured into water (5 mL) and extracted with ethyl acetate (3×3 mL). The combined organic extracts were washed with brine (2×2 mL), dried over sodium sulfate, filtered and concentrated in vacuo to a yellow solid. The crude product was purified by chromatography using a 13 g C-18 column gradient eluted from 10% acetonitrile in water up to 100% acetonitrile. The product containing fractions were combined and concentrated in vacuo and the residue lyophilized from acetonitrile/water to give (R)-2-(3-(6-tert-butylnicotinamido)piperidin-1-yl)-5-(pyridin-2-ylamino)thiazole-4-carboxamide as a pale yellow solid (37.8 mg, 66%).
