A high-pressure steel reactor (Parr) with CO-gas inlet was charged with 3-bromo-6-methyl-1-[3-(trifluoromethyl)phenyl]pyrazin-2(1H)-one (SM1, 0.30 g, 0.89 mmol), Pd(OAc)2 (0.035 g, 0.16 mmol), PPh3 (0.070 g, 0.26 mmol) and 5-methanesulfonyl-pyridine-2-ylamine (0.46 g, 1.79 mmol) in methanol (25 ml). To this mixture was added triethylamine (1.5 ml, 1.09 g, 10 mmol) and a magnetic stirrer bar. The reactor was ventilated with CO and 6 atmospheres CO-pressure was applied to the system. The reactor was heated to 90° C., the mixture was vigorously stirred, and the reaction was allowed to proceed for 4 h, and was then allowed to cool. The volatiles were removed in vacuo and the crude product was purified by preparative HPLC, which gave 0.22 g (53%) of 5-methyl-N-{[5-(methylsulfonyl)-pyridin-2-yl]methyl}-3-oxo-4-[3-(trifluoromethyl)-phenyl]-3,4-dihydropyrazine-2-carboxamide as a white solid, after freeze-drying the pure fractions.
