Glycine methyl ester hydrochloride → (2-Tert-butoxycarbonylamino-2-methylpropylamino)acetic acid methyl ester

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Reaction Steps

Amino-acetic acid methyl ester hydrochloride (80.6 g) and Et3N (160 mL) were dissolved in DCM (1000 mL) and stirred for 15 min to liberate the amine from the salt. Then a solution of 1,1-dimethyl-2-oxo-ethyl)-carbamic acid tert-butyl ester (compound M; 29.0 g) in DCM (600 mL) was added. The resulting mixture was stirred for 0.5 hour at ambient temperature before NaBH(OAc)3 (102 g) was added and the mixture was stirred at ambient temperature overnight. Sat. aqueous NaHCO3 was added. The aqueous layer was extracted with DCM. The combined organic layers were dried over Na2SO4, filtered, and concentrated in vacuo. The residue was purified by silica gel chromatography to afford (2-tert-butoxycarbonylamino-2-methyl-propylamino)-acetic acid methyl ester (compound N, 26.5 g) as white solid which was used directly in the next step.

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