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

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Reaction Steps

8-Methyl-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester hydrochloride 39c crude product (0.289 g, 0.96 mmol) and (R)-3-tert-butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyric acid if (0.353 g, 1.06 mmol) were dissolved in 10 mL of dichloromethane, followed by addition of triethylamine (0.4 mL, 2.9 mmol) and bis(2-oxo-3-oxazolidinyl)phosphinic chloride (0.368 g, 1.45 mmol) under stirring. The reaction mixture was stirred at room temperature overnight and monitored by thin layer chromatography until the disappearance of the starting materials. The reaction mixture was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography to obtain the title compound (R)-7-[3-tert-butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyryl]-8-methyl-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester 39d (0.43 g, yield 77.2%) as a yellow oil.

Provenance & Evidence