Diisopropylethylamine → 4-[[3-[3-(difluoromethyl)-6,8-dihydro-5H-[1,2,4]triazolo[4,3-a]pyrazine-7-carbonyl]-4-fluoro-phenyl]methyl]-2H-phthalazin-1-one

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Reaction Steps

2-Fluoro-5-[(4-oxo-3H-phthalazin-1-yl)methyl]benzoic acid 1a (685 mg, 2.30 mmol) was dissolved in 10 mL of N,N-dimethylformamide, followed by addition of O-(1-benzotriazolyl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (1.10 g, 3.45 mmol), crude 3-(difluoromethyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazine 23d (400 mg, 2.30 mmol) and N,N-diisopropylethylamine (1.2 mL, 6.90 mmol). After stirring for 12 hours, the reaction mixture was concentrated under reduced pressure and the resulting residue was purified by thin layer chromatography with elution system A to obtain 4-[[3-[3-(difluoromethyl)-6,8-dihydro-5H-[1,2,4]triazolo[4,3-a]pyrazine-7-carbonyl]-4-fluoro-phenyl]methyl]-2H-phthalazin-1-one 23 (200 mg, yield 20.0%) as a white solid.

Provenance & Evidence