(S)-3-(hydroxymethyl)-7,8,9,10-tetrahydro-5H-dipyrido[1,2-a:3′,2′-e]pyrazin-6(6aH)-one (150 mg, 0.643 mmol), 3-chloro-N-cyclopropyl-4-(piperazin-1-yl)benzamide (216 mg, 0.772 mmol), (cyanomethyl)trimethylphosphonium iodide (250 mg, 1.029 mmol) and N,N-diisopropylethylamine (562 μl, 3.22 mmol) were suspended in Propiononitrile (Volume: 1931 μl) and heated in a closed vial at 100° C. for 4 h. The reaction mixture became a dark brown solution with a precipitate. It was cooled to room temperature and the precipitate was filtered off, washed with MeCN (2 mL) and suspended in MeCN (15 mL) with heating and sonication. It was then cooled to ambient temperature, the precipitate was filtered off, washed with MeCN (2 mL) and dried in vacuum to afford (S)-3-chloro-N-cyclopropyl-4-(4-((6-oxo-6,6a,7,8,9,10-hexahydro-5H-dipyrido[1,2-a:3′,2′-e]pyrazin-3-yl)methyl)piperazin-1-yl)benzamide (272.4 mg, 0.550 mmol, 86% yield) as a white solid. 1H NMR (DMSO-d6) δ 10.49 (s, 1H), 8.39 (d, J=4.3 Hz, 1H), 7.85 (d, J=2.0 Hz, 1H), 7.75 (dd, J=8.3, 2.0 Hz, 1H), 7.66 (s, 1H), 7.16 (d, J=8.6 Hz, 1H), 6.97 (d, J=1.8 Hz, 1H), 4.50 (d, J=12.9 Hz, 1H), 3.84 (dd, J=11.4, 2.8 Hz, 1H), 3.38 (s, 2H), 3.02 (br. s., 4H), 2.77-2.88 (m, J=0.8 Hz, 1H), 2.60 (td, J=12.6, 2.5 Hz, 1H), 2.49-2.55 (m, J=3.5, 1.8, 1.8 Hz, 4H), 2.04 (br. d, J=12.6 Hz, 1H), 1.86-1.87 (m, OH), 1.84 (br. s., 1H), 1.64 (br. d, J=12.6 Hz, 1H), 1.32-1.57 (m, 3H), 0.61-0.72 (m, 2H), 0.51-0.61 (m, 2H); [M+H] calc'd for C26H31ClN6O2, 495. found, 495.
