3392-05-0

15761-38-3

107960-02-1

3392-05-0

Example 11: Preparation of N-succinimidyl N-tert-butoxycarbonyl-L-alanine ester 0.95 g (5 mmol) of N-tert-butoxycarbonyl-L-alanine and 0.66 ml (5.5 mmol) of N-methylmorpholine were dissolved in 6 ml of tetrahydrofuran (THF), followed by a one-time addition of 1.8 g (5.5 mmol) of N-succinimidyl 1,2,2,2-tetrachloroethyl carbonate. The reaction mixture was stirred at 20°C for 2 hours. After completion of the reaction, it was diluted by adding about 25 ml of ethyl acetate, and the organic phase was washed quickly with 1N HCl solution, potassium bicarbonate solution in sequence, and finally washed twice with water. The organic phase was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was recrystallized by ethyl acetate/petroleum ether mixed solvent to give 1.25 g (87% yield) of white crystals. Evaporation of the mother liquor and recrystallization recovered 0.1 g of product, raising the overall yield to 94%. The melting point of the product was 158 °C. [α]D20 = +50.7 (c = 2, dioxane).