The new histidine derivative 3-{1-[3-(9H-fluoren-9-ylmethoxycarbonylamino)-propyl]-1H- imidazol-4-yl}-2-(3-trimethylsilanyl-ethylcarboxyamino)-propionic acid methyl ester (7) has been prepared via alkylation of the histidine urea derivative (7S)-5, 6, 7, 8-tetrahydro-7- (methoxycarbonyl)-5-oxoimidazo-[1, 5-c]-pyrimidine (2) with Fmoc-protected 3-iodopropyl- amine, followed by ring opening with 2-trimethylsilylethanol. After Fmoc cleavage by ...