beta-Alanine, ethyl ester, hydrochloride → Ethyl 4-(tert-butyldimethylsilyloxy)-3-(3-ethoxy-3-oxopropylamino)butanoate

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Reaction Steps

Ethyl 3-aminopropanoate HCl salt (4.6 g, 39.2 mmol, 1.4 eq) was added to a solution of (E)-ethyl 4-(tert-butyldimethylsilyloxy)but-2-enoate in 50 mL of ethanol. The mixture was stirred at RT overnight and then heated to reflux overnight. Another 9.2 g of 3-aminopropanoate HCl salt was added. The reaction was continued to heat at reflux for 2 hr. Solvents were removed; the yellow oily residue was dissolved in DCM, filtered through a pad of SiO2 (˜80 g), and washed with 800 mL EtOAc. The filtrate was concentrated to give the product 7.8 g (76%) as a light yellow liquid. HPLC retention time: T=1.844 min (analytical-3); ESI-MS:m/z 362.3 (M+H)+.

Provenance & Evidence