To a solution of (R)-4-(2-methylpiperazin-1-yl)-1-phenylpyrido[3,4-d]pyridazine 16 (105 mg, 344 μmol) in 5 mL of CH2Cl2 was added triethylamine (96 μl, 688 μmol) followed by 4-morpholinylcarbonyl chloride (55 μl, 413 μmol). After 4 h, the reaction was diluted with 60 mL of EtOAc and washed with sat. NaHCO3 and brine. The organic layer was dried over MgSO4, filtered, and concentrated. Purification by column chromatography afforded (R)-(3-methyl-4-(1-phenylpyrido[3,4-d]pyridazin-4-yl)piperazin-1-yl)(morpholino)methanone 36. MS 418.2 (calc'd) 419.2 (M+H, found).
