Morpholine → tert-butyl 1-(morpholine-4-carbonyl)-3-(trifluoromethyl)-6,8-dihydro-5H-imidazo[1,5-a]pyrazine-7-carboxylate

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Reaction Steps

7-Tert-butoxycarbonyl-3-(trifluoromethyl)-6,8-dihydro-5H-imidazo[1,5-a]pyrazine-carboxylic acid 20a (330 mg, 1 mmol) was dissolved in 5 mL of N,N-dimethylformamide, followed by addition of O-(1-benzotriazolyl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (756 mg, 2 mmol), morpholine (174 mg, 2 mmol) and N,N-diisopropylethylamine (0.5 mL, 3 mmol). After stirring for 12 hours, the reaction mixture was concentrated under reduced pressure, added with 20 mL of saturated ammonium chloride solution, extracted with dichloromethane (20 mL×3). The organic phase was combined, dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the resulting residue was purified by thin layer chromatography with elution system A to obtain tert-butyl 1-(morpholine-4-carbonyl)-3-(trifluoromethyl)-6,8-dihydro-5H-imidazo[1,5-a]pyrazine-7-carboxylate 20b (400 mg, yield 100.0%) as a yellow solid.

Provenance & Evidence