4-Methylmorpholine → 2-[2-({[2-(4-Bromo-phenyl)-2-oxo-ethyl carbamoyl]-methyl}-tert-butoxycarbonyl-amino)-acetylamino]-3-methyl-butyric acid methyl ester

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Reaction Steps

4-Methylmorpholine (4.1 mL, 37.3 mmol) was added to a suspension of ({[2-(4-bromo-phenyl)-2-oxo-ethylcarbamoyl]-methyl}-tert-butoxycarbonyl-amino)-acetic acid (4 g, 9.3 mmol), and HATU (4.61 g, 12.1 mmol) in dimethylformamide (25 mL). After 5 minutes d-valine methyl ester hydrochloride (1.56 g, 9.3 mmol), was added to the solution. After 1 hour the solvent was removed under reduced pressure. The residue was taken up in ethyl acetate (150 mL), and washed with water (100 mL), aqueous hydrogen chloride (0.5 N, 2×100 mL), saturated sodium bicarbonate (100 mL), and saturated sodium chloride (100 mL). The organic phase was dried over sodium sulfate, filtered and the solvent was removed under reduced pressure. The residue was subjected to flash chromatography with eluent of (10% methanol in ethyl acetate) and hexane. The product-containing fractions were combined and the solvent was removed under reduced pressure to yield 2-[2-({[2-(4-bromo-phenyl)-2-oxo-ethylcarbamoyl]-methyl}-tert-butoxycarbonyl-amino)-acetylamino]-3-methyl-butyric acid methyl ester (4.37 g, 8.1 mmol, 87%). C23H32BrN3O7 calculated 541.1 observed [M+1]+ 431.1; rt=2.65 min.

Provenance & Evidence