A mixture of 3-(4-isopropyl-1-piperazinyl)-2(1H)-pyrazinone (0.58 g, 2.6 mmol; from Step 2) and t-BuOK (440 mg, 3.90 mmol) in THF (40 mL) was stirred until the mixture became thick (about 10 min), and then a solution of 2-(2,4,5-trifluorophenoxy)ethyl methanesulfonate (0.90 g, 2.2 mmol; from Example 54, Step 4) in THF (10 mL) was added. After being stirred for 5 days at ambient temperature, HPLC showed only 25% conversion. The reaction solution was then heated to 60° C. overnight which gave almost full conversion. The reaction was worked up according to the following: water was added, THF was evaporated off and the aqueous mixture was extracted twice with EtOAc, dried and concentrated to yield 1.18 g of the crude product as a yellow oil. Purification by chromatography on silica gel (eluent: 2.5% MeOH in CHCl3+NH3 (g)) gave the title compound as a colourless oil, which solidified upon cooling. Yield: 120 mg (14%). HPLC purity: 99%. MS m/z 397 (M+H)+. HRMS m/z calcd for C19H23F3N4O2 (M)+ 396.1773, found 396.1771.
