Ethyl chloroacetate → (R)-7-[3-tert-Butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester

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Reaction Steps

Refer to Journal of Organometallic Chemistry, 1985, 285(1-3), 293-303. Octacarbonyldicobalt (4.02 g, 11.76 mmol), ethyl chloroacetate (0.71 g, 5.88 mmol), potassium carbonate (1.62 g, 11.76 mmol) and 50 mL of methanol were added into the reaction flask. After stirring for 5 minutes, tert-butyl (R)-[3-oxo-1-(2,4,5-trifluoro-benzyl)-3-(1-bromo-3-trifluoromethyl-5,6-dihydro-8H-imidazo[1,5-a]pyrazin-7-yl)-prop yl]-carbamate 1n (2.3 g, 3.92 mmol) was added. The reaction mixture was stirred at 60° C. for 2 hours and then concentrated under reduced pressure. The resulting residues were purified by silica gel column chromatography with system B as eluant to obtain the title compound methyl (R)-7-[3-tert-butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-formate 1p (1.1 g, yield 50%) as a white solid. MS m/z (ESI): 565.0 [M+1].

Provenance & Evidence