Hydrochloric Acid → 4-[2-(4-Bromo-phenyl)-2-oxo-ethylcarbamoyl]-3-(2-methoxycarbonylamino-3-methyl-butyryl)-imidazolidine-1-carboxylic acid tert-butyl ester

Participants

Reaction Steps

3-(2-Methoxycarbonylamino-3-methyl-butyryl)-imidazolidine-1,4-dicarboxylic acid 1-tert-butyl ester 4-methyl ester (460 mg, 1.18 mmol) was dissolved in THF (3 mL) and MeOH (2 mL). An aqueous solution of LiOH (49.8 mg, 1.18 mmol) was added and stirring at room temperature was continued. After the hydrolysis was complete, the reaction was neutralized with aqueous HCl (1.18 mL, 1M). The organic solvents were removed in vacuo and the aqueous suspension was frozen and lyophilized. The crude material was used in the next step without further purification. The crude material was dissolved in DMF (4.0 mL) and HATU (448 mg, 1.18 mmol) and DIEA (152 mg, 1.18 mmol) were added. The reaction was stirred at room temperature for five minutes, after which the amino-(4′bromo) acetophenone hydrochloride salt (295 mg, 1.18 mmol) was added. Stirring at room temperature was continued. After 90 minutes, all volatiles were removed in vacuo and the crude material was purified via silica gel chromatography (eluent: EtOAc/hexanes) to yield the slightly impure product 4-[2-(4-Bromo-phenyl)-2-oxo-ethylcarbamoyl]-3-(2-methoxycarbonylamino-3-methyl-butyryl)-imidazolidine-1-carboxylic acid tert-butyl ester (723 mg): LCMS-ESI+: calc'd for C24H33BrN4O7: 569.4 (M+). Found: 570.4/572.4 (M+H+).

Provenance & Evidence