Compound N2′-(4-aminocyclohexyl)-3,5′-dichloro-N6-((tetrahydro-2H-pyran-4-yl)methyl)-2,4′-bipyridine-2′,6-diamine (0.100 g, 0.222 mmol) (synthesized in the same manner as in Example 1b), 2,3,5,6-tetrahydro-4H-thiopyran-4-one 1,1-dioxide (0.036 g, 0.244 mmol), and triethylamine (0.251 ml, 0.182 g, 1.798 mmol) were dissolved in anhydrous CH2Cl2 (1.0 ml) and placed under argon. This solution was then treated with sodium triacetoxyborohydride (0.094 g, 0.444 mmol). The reaction was then stirred at room temperature for 18 hours. At this time a LC-MS was run. The reaction was about 25% complete. Additional 2,3,5,6-tetrahydro-4H-thiopyran-4-one 1,1-dioxide (˜4 equivalents) and sodium triacetoxy borohydride (˜8 equivalents) were added and the reaction continued for additional 27 hours. The reaction was about 60% complete as indicated by LC/MS. The reaction was quenched with sat NaHCO3 (15 ml). This was extracted with EtOAc (3×15 ml). The combined extracts were washed with brine (1×15 ml), dried (Na2SO4), filtered and the solvent removed in vacuo. The material was purified using the HPLC and lyophilized to give 19.7 mg off-white powder of the title compound as its TFA salt. LCMS (m/z): 582/584 (MH+), retention time=0.58 min.
