To a solution of (R)-(1-(4-amino-5-nitropyrimidin-2-yl)piperidin-3-yl)(pyrrolidin-1-yl)methanone (0.5 g, 1.5 mmol) in a mixture of ethanol and water were added 5-bromonicotinaldehyde (0.35 g, 1.6 mmol) and sodium dithionate (1.1 g, 5.9 mmol). The reaction mixture was heated to 120° C. for 16 h. The reaction mixture was concentrated and partitioned between water and ethyl acetate. The organics were concentrated under reduced pressure and the resulting crude was purified via preparative TLC to afford (R)-(1-(2-(5-bromopyridin-3-yl)-3H-imidazo[4,5-b]pyridin-5-yl)piperidin-3-yl)(pyrrolidin-1-yl)methanone (400 mg, 60%).
