Reagents and conditions: (a) N-hydroxysuccinimide, DCC, THF, 0 °C–rt, 12 h, 93%; (b) l-glutamic acid, NaOH solution (aq), dioxane, 4 h, 0 °C–rt, 90%; (c) HN(OCH3)CH3, EDC·HCl, HOBt, DMF, rt, 12 h, 90%; (d) thiazole, n-BuLi, −78 °C, 2.5 h followed by HPLC purification.