Lithium Bromide → Methyl (S)-2-benzyloxycarbonylamino-4-oxo-5-phenylpentanoate

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Reaction Steps

To a suspension of copper(I) bromide-dimethyl sulfide complex (2.6 g, 12.72 mmol, 1.2 eq.) in dry THF was added a solution of lithium bromide (2.2 g, 25.44 mmol, 2.4 eq.) in dry THF. The mixture was stirred at room temperature (RT) for 20 min, and then was cooled to −78° C. A solution of benzyl magnesium chloride (13 mL, 12.72 mmol, 1.2 eq.) followed by a solution of (S)-methyl 2-(benzyloxycarbonylamino)-4-chloro-4-oxobutanoate (3.16 g, 10.6 mmol, 1 eq.) in dry THF were added. The mixture was stirred at −78° C. for 30 min and then was quenched with sat. ammonium chloride. The mixture was extracted with ethyl acetate. The organic layers were dried over magnesium sulfate and then concentrated in vacuo. The residue was purified by flash column (1:1 ethyl acetate:hexane) to give 2 g of (S)-methyl 2-(benzyloxycarbonylamino)-4-oxo-5-phenylpentanoate.

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