Hydrochloric Acid → tert-butyl (2S,4R)-2-(6-bromo-4-oxo-3,4-dihydrothieno[3,2-d]pyrimidin-2-yl)-4-phenoxypyrrolidine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

A solution of (4R)-1-(tert-butoxycarbonyl)-4-phenoxy-L-proline (1.04 g), O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (1.29 g) and N-ethyl-N-(1-methylethyl)propan-2-amine (0.692 mL) in N,N-dimethylformamide (5 mL) was stirred at room temperature for 30 min. To the reaction mixture was added 3-amino-5-bromothiophene-2-carboxamide (250 mg) produced in Example 1, step D, and the mixture was stirred at 90° C. for 1.5 hr. The reaction mixture was concentrated under reduced pressure, ethyl acetate (20 mL) and aqueous sodium hydrogen carbonate (10 mL) were added to the obtained residue, and the separated aqueous layer was extracted with ethyl acetate (5 mL). The combined organic layers were washed with brine (5 mL) and dried over anhydrous sodium sulfate. Insoluble material was filtered off, and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/hexane) to give an inseparable mixture of tert-butyl(2S,4R)-2-[(5-bromo-2-carbamoylthiophen-3-yl)carbamoyl]-4-phenoxypyrrolidine-1-carboxylate and impurity having an undetermined structure as a pale-yellow solid. To a solution of the inseparable mixture of tert-butyl(2S,4R)-2-[(5-bromo-2-carbamoylthiophen-3-yl)carbamoyl]-4-phenoxypyrrolidine-1-carboxylate produced above and impurity having an undetermined structure in ethanol (5 mL) was added 2M aqueous sodium hydroxide solution (1.70 mL), and the mixture was stirred at 70° C. for 2 hr. 6M Hydrochloric acid (0.60 mL) was added to the reaction mixture, and the precipitated solid was collected by filtration, and washed successively with water (5 mL), ethanol (5 mL) and diethyl ether (5 mL) to give the title compound (440 mg) as a colorless solid.

Provenance & Evidence