Isobutyl chloroformate → HCID 71147201, compound

Participants

Reaction Steps

To a solution of (2S)-1-(tert-butoxycarbonyl)piperidine-2-carboxylic acid (518 mg) and triethylamine (0.392 mL) in tetrahydrofuran (5 ml) was added 2-methylpropyl chlorocarbonate (0.309 mL) at 0° C., and the mixture was stirred at room temperature for 30 min. To the reaction mixture was added a solution of 3-amino-5-bromothiophene-2-carboxamide (250 mg) produced in Example 1, step D, in tetrahydrofuran (5 mL), and the mixture was stirred at 60° C. for 15 hr. Ethyl acetate (20 mL) and aqueous sodium hydrogen carbonate (10 mL) were added to the reaction mixture, 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 to give tert-butyl 2-[(5-bromo-2-carbamoylthiophen-3-yl)carbamoyl]piperidine-1-carboxylate as a pale-yellow oil. To a solution of tert-butyl 2-[(5-bromo-2-carbamoylthiophen-3-yl)carbamoyl]piperidine-1-carboxylate produced above in ethanol (5 mL) was added 2M aqueous sodium hydroxide solution (1.70 mL), and the mixture was stirred at 70° C. for 4 hr. The reaction mixture was neutralized with 6M hydrochloric acid (0.6 mL) under ice-cooling, and water (5 mL) was added dropwise at room temperature. The precipitated solid was collected by filtration to give the title compound (240 mg) as a pale-yellow solid.

Provenance & Evidence