2,4,5-Trichlorophenyl-(9<i>H</i>-fluoren-9-ylmethoxycarbonylamino)methylcarbamates: Synthesis, isolation, characterization and utility in the synthesis of dipeptidyl ureas

Abstract

An efficient synthesis of 2,4,5-trichlorophenyl-(9<i>H</i>-fluoren-9-ylmethoxycarbonylamino)methylcarbamates employing isocyanates derived from several Fmoc-amino acids has been described. All the carbamates made have been obtained as crystalline solids and are fully characterized by IR, ¹H NMR, ¹³C NMR and mass spectrometry. They have been used as building blocks for the synthesis of several dipeptidyl urea esters. The coupling of carbamates with <i>N,O</i>-bis[trimethyl­silyl]amino acids resulted in Fmoc-protected dipeptide urea acids in good yield as well as purity. All the dipeptidyl urea esters and acids made have been well characterized.