A mixture of (R)-tert-butyl 3-((2′-(trans-4-aminocyclohexylamino)-5′-chloro-2,4′-bipyridin-6-yl-amino)methyl)piperidine-1-carboxylate (36 mg, 0.070 mmol), DCM (1.2 ml), TEA (0.019 ml, 0.140 mmol) and benzyl 2,5-dioxopyrrolidin-1-yl carbonate (26.1 mg, 0.105 mmol) was stirred at ambient temperature for 2 hours and the reaction progress was followed by LCMS. To this crude reaction mixture was added 25 ml of ethyl acetate, washed with 2M sodium carbonate, water (2×) and saturated salt solution (1×), dried with sodium sulfate, filtered, concentrated to crude intermediate. To the crude intermediate was added 4M HCl in Dioxane (2 ml, 8.00 mmol) and stirred at ambient temperature for 1 hour. The crude reaction mixture was concentrated to constant mass, dissolved in 1 ml of DMSO and purified by prep LC. After lyophilization, 15 mg of the title compound, was obtained as a TFA salt. LCMS (m/z): 549.4 (MH+), retention time=0.67 min.
