A mixture of 4-(5-iodo-6-trifluoromethyl-pyridazin-3-yl)-piperazine-1-carboxylic acid tert-butyl ester (D10) (0.20 g, 0.436 mmol), 5-chlorothiophene-2-boronic acid (0.082 g, 0.51 mmol), tetrakis(triphenylphosphine)palladium (0) (0.024 g, 0.021 mmol) and sodium carbonate (0.103 g, 0.96 mmol) in dimethoxyethane (3 ml) and water (0.75 ml) was stirred in a sealed tube at 110° C. for 16 h. The mixture was then filtered through a pad of diatomaceous earth and the solvent was evaporated in vacuo. The residue was purified by column chromatography (silica gel; dichloromethane/10% ammonia in methanol (7M) in dichloromethane 97/3) to yield D15 (0.152 g, 67%) as a yellow syrup. C18H20ClF3N4O2S requires 448; Found 449 (MH+).
