In a 500mL single-neck round-bottomed flask, dissolve 19.3g Pal-Lys(Cbz)-OH in 300mL methylene chloride. Under ice bath conditions, add 6.4g N-hydroxysuccinimide (NHS), 0.91g DMAP and 10.7g EDCl. , after the addition, gradually returned to room temperature and stirred for 18 hours. After...