1-amino-3-(benzyloxy)-5-chloropyrazin-1-ium 2,4,6-trimethylbenzenesulfonate (5.34) (657 mg, 1.51 mmol) was suspended in 1,4-dioxane (5.75 mL) and acrylonitrile (0.23 mL, 3.5 mmol) was added followed by iPr2NEt (0.32 mL, 1.9 mmol). The resulting mixture was stirred for 1.75 h at r.t. and DDQ (720 mg, 3.2 mmol) was added in one portion. The resulting mixture was stirred an additional 1 h and was then partitioned between EtOAc, water and brine. The phases were separated and the aqueous phase was extracted with EtOAc. The combined organic phase was dried over Na2SO4, filtered, and concentrated. The concentrate was purified by silica gel chromatography (0-20% EtOAc in hexanes) to provide 4-(benzyloxy)-6-chloropyrazolo[1,5-a]pyrazine-3-carbonitrile. 1H NMR (400 MHz, Chloroform-d) δ 8.22 (s, 1H), 8.18 (s, 1H), 7.61-7.55 (m, 2H), 7.45-7.39 (m, 2H), 7.39-7.33 (m, 1H), 5.67 (s, 2H).
