Triethylamine → N-(2(S)-(t-butoxycarbonylamino)-3(S)-methylpentyl)glycine methyl ester

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Reaction Steps

Glycine methyl ester hydrochloride (4.41 g, 0.035 mol) was dissolved in 1,2-dichloroethane (50 mL) and DMF (5 mL) and treated with 3A molecular sieves (10 g) and N-t-butoxycarbonyl-isoleucinal (6.3 g, 0.029 mol) with stiring at 0° C. Sodium triacetoxyborohydride (9.27 g, 0.044 mol) was added, and the pH of the mixture was adjusted to 6 with triethylamine (3 ml, 0.022 mol). After stirring for 18 h the mixture was filtered, concentrated and partitioned between EtOAc and water. The aqueous layer was extracted with EtOAc (2×50 mL). The combined organic extracts were washed with aqueous saturated NaHCO3 solution, brine, and dried (Na2SO4). Filtration and evaporation in vacuo afforded a residue which was purified by flash chromatography (SiO2, EtOAc:hexane, 1:3) to give the title compound as an oil.

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