Bromine → 7-Benzyl-1-bromo-5,6,7,8-tetrahydroimidazo[1,5-a]pyrazine

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Reaction Steps

7-Benzyl-3-bromo-5,6,7,8-tetrahydroimidazo[1,5-a]pyrazine: The synthesis of 7-benzyl-3-bromo-5,6,7,8-tetrahydroimidazo[1,5-a]pyrazine is described in PCT/IB03/00998 WO 03/076427 A1. A solution of 7-benzyl-5,6,7,8-tetrahydro imidazo[1,5-a]pyrazine (450 mg, 2.110 mmol) in THF was cooled in dry ice acetone bath. n-Butyllithium (0.928 mL, 2.321 mmol) was added dropwise. After 15 mins, bromine (0.120 mL, 2.321 mmol) was added dropwise. After 1 h, the solution was poured into H2O and extracted with DCM (3×). Purified by normal phase chromatography to afford 7-benzyl-1-bromo-5,6,7,8-tetrahydroimidazo[1,5-a]pyrazine (112 mg, 0.383 mmol, 18.2% yield) and 71A (260 mg, 0.890 mmol, 42.2% yield). 1H NMR (400 MHz, CDCl3) δ 7.18-7.44 (m, 5H) 6.71 (s, 1H) 3.78-3.95 (m, 2H) 3.68 (s, 2H) 3.60 (s, 2H) 2.75-2.97 (m, 2H) ppm.

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