C([O:5][C:6](=[O:26])[CH2:7][CH2:8][N:9]([CH2:11][CH2:12][CH:13]1[C:25]2[CH:24]=[CH:23][CH:22]=[CH:21][C:20]=2[C:19]2[C:14]1=[CH:15][CH:16]=[CH:17][CH:18]=2)[CH3:10])(C)(C)C.FC(F)(F)C(O)=O.C([O-])(O)=O.[Na+]>ClCCl>[CH:15]1[C:14]2[CH:13]([CH2:12][CH2:11][N:9]([CH3:10])[CH2:8][CH2:7][C:6]([OH:26])=[O:5])[C:25]3[C:20](=[CH:21][CH:22]=[CH:23][CH:24]=3)[C:19]=2[CH:18]=[CH:17][CH:16]=1A solution of 3-{[2-(9H-fluoren-9-yl)-ethyl]-methyl-amino}-propionic acid tert-butyl ester (11.4 g) in 20 ml dichloromethane is cooled to 0°. Trifluoroacetic acid (20 ml) is added and the solution stirred at room temperature over night. To this mixture a 1 M aq. NaHCO3 solution (262 ml) is added dropwise under vigorous stirring. The phases are separated, the water phase acidified with 14 ml 2N HCl and extracted several times with dichloromethane. The combined extracts are dried over sodium sulfate, filtered and evaporated to afford 11.4 g (100%) of a light brown foam which is used without purification. TLC (silicagel, dichloromethane/methanol 85:15): rf 0.3.
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