| 内容提要: |
N-carbobenzyloxy-L-lysine (Lys (Z)) (1 g, 3.57 mmol) was suspended in 50 mL round bottomed flask, afterward 10 mL anhydrous THF was added with the nitrogen protection. Then, triphosgene (0.389 g, 1.31 mmol) dissolved in 8 mL anhydrous THF was added at ambient temperature by oxygen removal. The reaction was carried out at 50oC until no apparent solids in the bottom (around 3 h). The reaction mixture was filtered to remove the excess Lys (Z). After that, the filter liquor was concentrated to 5 mL by reduce pressure and then precipitated in 40 mL hexane with ice bath. The precipitate was dissolved in 3 mL anhydrous THF, followed by crystallization in iced hexane for 3 h under 0oC. The white crystal solid, Lys(Z)-NCA monomer, was obtained by filtration. The product was drying under vacuum prior to weighing, the mass was 700 mg and the mole was 2.29 mmol, the yield was 70 %. |