Diisopropyl Ether → N2-[(9H-Fluoren-9-ylmethoxy)carbonyl]-N-(triphenylmethyl)-L-glutamine 2,3,4,5,6-pentafluorophenyl ester

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Reaction Steps

1.5 g (2.27 mmol) of Fmoc-Gln(Trt)-OH×0.5 diisopropyl ether and 0.46 g (2.5 mmol) of pentafluoro-phenol are dissolved in 35 ml of ethyl acetate, cooled to 0° and, while stirring, 0.52 g (2.5 mmol) of dicyclohexylcarbodiimide is added. The mixture is stirred at 0° for 1 hour and at room temperature for 3 hours, and insoluble material is filtered off and washed with tetrahydrofuran. The filtrate is evaporated to dryness, and the residue is dissolved in 30 ml of tetrahydrofuran. Slow addition of petroleum ether while stirring results in crystallization of Fmoc-Gln(Trt)-OPfp; m.p. 185°-187°, [α]D20 =-16.4° (THF).

Provenance & Evidence