Synthesis
N-Γ-triphenylmethyl-L-glutamic acid pentafluorophenyl ester was suspended in a dioxane solution and acylated with fluorenemethyloxycarbonyl azide to obtain FMOC-GLN(TRT)-OPFP[1]. The reaction formula is shown in the figure below:
Experimental procedure:
Place N-Γ-triphenylmethyl-L-glutamic acid pentafluorophenyl ester into a round-bottom flask, add anhydrous ethanol and a rotor into the round-bottom flask, and place the round-bottom flask in a silicone oil heater to heat to 80°C. When the liquid becomes homogeneous, add potassium hydroxide into the round-bottom flask. After reacting for 1 hour, the liquid changes from turbid to transparent. Add tert-butyllithium, and the liquid becomes transparent pale yellow. Continue the reaction for 2 hours. The liquid color does not change. Thin-layer chromatography is used to detect the reaction progress. Stop the reaction after the starting materials have reacted completely. After cooling to room temperature, filter to obtain a pale yellow powder. Anhydrous dioxane and a rotor were added to a round-bottom flask. N-Γ-triphenylmethyl-L-glutamic acid pentafluorophenyl ester was suspended in the dioxane solution and subjected to an acylation reaction with fluorenemethyloxycarbonyl azide. The reaction progress was monitored by thin-layer chromatography. The reaction was stopped after the starting material had completely reacted, yielding crude FMOC-GLN(TRT)-OPFP. This crude product was extracted with ethyl acetate at pH 9-10 and then purified by recrystallization.
