To a solution of (R)-4-(2-methylpiperazin-1-yl)-1-phenylpyrido[4,3-d]pyridazine 16 (125 mg, 409 μmol) in dichloromethane (5 mL) was added HOBT (3.1 mg, 20 μmol), EDCI (86 mg, 450 μmol), triethylamine (114 μl, 819 μmol), and tetrahydro-2H-pyran-4-carboxylic acid (64 mg, 491 μmol). After 1 hour, 10 mL of sat NaHCO3 and 100 mL of ethyl acetate were added. The layers were separated and the organic layer was washed with 1×10 mL of brine, dried over MgSO4, filtered, and concentrated. Purified by column chromatography (hexanes:acetone) to isolate (R)-(3-methyl-4-(1-phenylpyrido[4,3-d]pyridazin-4-yl)piperazin-1-yl)(tetrahydro-2H-pyran-4-yl)methanone 30. MS: 417.2 (calc'd) 418.1 (M+H, found).
