N-Boc-N-methyl glycine methyl ester

24424-99-5

13515-93-0

42492-57-9

Thionyl chloride (29.02 mL, 0.40 mol) was slowly added dropwise to a suspension of sarcosine methyl ester hydrochloride (35.64 g, 0.40 mol) in 350 mL of methanol at 0 °C. After completion of the dropwise addition, the ice bath was removed and the reaction mixture was stirred at room temperature for 30 minutes followed by reflux for 6 hours. Upon completion of the reaction, the solution was concentrated under reduced pressure and the residue was dried overnight under high vacuum to afford sarcosine methyl ester hydrochloride in the form of a white powder, which could be used in the next step of the reaction without further purification. Yield: 56.14 g (quantitative); Melting point: 102°C. NMR hydrogen spectrum (300 MHz, CDCl3): δ=9.76 (s, 2H, NH2), 3.88 (t, J=5.6 Hz, 2H, CH2), 3.82 (s, 3H, OCH3), 2.83 (t, J=5.2 Hz, 3H, NCH3). NMR carbon spectrum (75MHz, CDCl3): δ=166.7 (C=O), 53.3 (CH2), 48.9 (NCH3), 33.4 (OCH3). Sarcosine methyl ester hydrochloride (59.80 g, 0.43 mol) was suspended in 1.0 L of dichloromethane, and a mixture of triethylamine (119.09 mL, 0.86 mol) and di-tert-butyl dicarbonate (138.01 mL, 0.65 mol) was added slowly and dropwise at 0 °C. After dropwise addition, the ice bath was removed and the reaction mixture was stirred at room temperature for 2 days. After completion of the reaction, the reaction was adjusted to pH=6 by adding 1 M aqueous hydrochloric acid, the organic layer was separated, washed with distilled water, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and volatile impurities were removed overnight under high vacuum to give the clarified oily product methyl 2-((tert-butoxycarbonyl)(methyl)amino)acetate. Yield: 78.65 g (90%).