Hydrochloric Acid → t-butoxycarbonylmethyl 5-(Boc-amino)-4-oxopentanoate

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Reaction Steps

Triethylamine (2.22 g; 22.0 mmol) was added dropwise to a stirred solution of 5-(Boc-amino)-4-oxopentanoic acid (4.62 g; 20.0 mmol) and t-butyl bromoacetate (4.30 g; 22.0 mmol) in ethyl acetate (60 mL) under argon at ambient temperature. The mixture (slurry) was refluxed for 17 h, then cooled to ambient temperature, poured into 0.5 M HCl (100 mL) and shaken thoroughly. The aqueous portion was extracted with ethyl acetate (2×20 mL). The combined organic solutions were washed with saturated NaHCO3 solution (1×20 mL) and saturated NaCl solution (1×20 mL) then dried (MgSO4), filtered and evaporated. Evaporation resulted in an amber oil that was purified by flash chromatography on a 40×55-mm silica gel 60 column eluted with ethyl acetate-hexane (1:1) (600 mL), collecting 5×100 mL fractions. Evaporation of fractions 1 and 2 resulted in 6.15 g (89%) product (yellow oil).

Provenance & Evidence