To a solution of 2-((2-chloro-5-cyano-3-(2-oxopiperazin-1-yl)phenyl)amino)-4-(cyclopropyl(4-methoxybenzyl)amino)imidazo[2,1-f][1,2,4]triazine-7-carbonitrile (17 mg, 0.030 mmol) in DCM (2 mL) was added acetaldehyde (13.16 mg, 0.299 mmol) and acetic acid (3.42 μl, 0.060 mmol). After stirring for 15 min, sodium triacetoxyborohydride (12.66 mg, 0.060 mmol) was added. After stirring at room temperature for 2 h, LC-MS indicated completion. After concentration, purification via flash chromatography (0-10% MeOH in DCM, 12 g) gave 20 mg of the PMB protected product. This was dissolved in 1 mL of DCE and then 1 drop of anisole was added followed by 0.5 mL of TFA. The solution was heated at 60° C. for 2.5 h. LC-MS indicated completion, and then it was cooled and concentrated. The crude was dissolved in methanol and neutralized with 7N ammonia in methanol. After stirring for 10 min it was concentrated, purification via preparative HPLC gave the title compound as a yellow solid (10 mg).
