Triethylamine → 7-Methyl-6-oxo-5,6,7,8-tetrahydroimidazo[1,2-a]pyrazine-2-carbaldehyde

関与物質

反応手順

The solution of 2-bromo-3-isopropoxy-propenal (1.3 g) in dry acetonitrile (60 mL) was added to the solution of 5-amino-1-methyl-3,6-dihydro-1H-pyrazin-2-one (782 mg) in dry acetonitrile (60 mL) at room temperature. The reaction mixture was stirred at room temperature for 20 h, added triethylamine (0.95 mL) and then refluxed for 2 h. The reaction mixture was cooled to room temperature and then evaporated under reduce pressure. The residue was dissolved in chloroform (10 mL) and washed with 50% K2CO3 aqueous solution (10 mL). The aqueous layer was extracted with chloroform. The organic layer was dried (MgSO4) and filtered. The filtrate was evaporated under reduce pressure. The residue was applied to silica gel column chromatography and eluted with CHCl3-MeOH (95:5) to obtain the title compound 7-Methyl-6-oxo-5,6,7,8-tetrahydro-imidazo[1,2-a]pyrazine-2-carbaldehyde as a pale yellow solid (541 mg, 49.1%) and its regio isomer 7-Methyl-6-oxo-5,6,7,8-tetrahydro-imidazo[1,2-a]pyrazine-3-carbaldehyde as a pale yellow solid (128 mg, 11.6%).

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