To (7R,8aS)-2-benzyloctahydropyrrolo[1,2-a]pyrazin-7-ol (Example 19D, 2.323 g, 10 mmol) in tetrahydrofuran (60 mL) at room temperature was added potassium tert-butoxide (14 mL, 1 M in tetrahydrofuran). After 10 minutes, 2-bromo-5-cyclopropylpyrazine (2.249 g, 11.3 mmol) in tetrahydrofuran (3 mL) was added. The mixture was stirred at room temperature for 2 days. The mixture was concentrated and diluted with dichloromethane (200 mL). This solution was washed with water (30 mL), dried over sodium sulfate, and filtered. The organic phase was concentrated. The residue was purified by chromatography on silica gel (dichloromethane/methanol=15:1) to give the title compound. 1H NMR (400 MHz, DMSO-d6) δ ppm 0.80 (m, 2H), 0.92 (m, 2H), 1.78 (m, 3H), 2.08-2.38 (m, 5H), 2.70 (m, 1H), 2.83 (m, 2H), 3.53 (m, 3H), 5.24 (m, 1H), 7.28 (m, 5H), 8.12 (m, 2H); MS (ESI) m/z 351 (M+H)+.
