Benzyl chloroformate → Ethyl 3-((benzyloxycarbonyl)(3-ethoxy-3-oxopropyl)amino)-4-(tert-butyldimethylsilyloxy)butanoate

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Reaction Steps

To the amine 3B (7.80 g, 21.6 mmol) and NaHCO3 (2.82 g, 33.6 mmol, 1.55 eq) in 40 mL anhydrous dioxane was added benzyl chloroformate (4.80 g, 28.1 mmol, 1.3 eq) at 0° C. over 5 mins. The ice bath was removed, and the mixture was allowed to warm to RT overnight. Solvents were removed in vacuo; the residue was diluted with 50 mL of water and 100 mL of EtOAc. The organic phase was separated, and the aqueous phase was further extracted with ethyl acetate (3×50 mL). The combined organic phase was dried over Na2SO4, and concentrated. The residue was chromatographed on SiO2 to afford 7.8 g (73%) of product 3C as a colorless liquid along with the recovery of 1.02 g starting material. ESI-MS:m/z 496.5 (M+H)+.

Provenance & Evidence