A general and efficient method has been developed for the alcoholysis of isocyanates derived from the N a -[(9-fluorenylmethyl)oxy]carbonyl amino acids with various alcohols including hindered ones assisted by MW irradiation. Thus, the synthesis of N, N 1 -diurethane protected gem-diamines wherein Fmoc protection on one of the amino groups and Z-/Boc-/Alloc or Bsmoc group on the other amino function has been accomplished. All the new orthogonally diurethane protected gem-diamines have been obtained as crystalline solid powders in 80 to 94% yield. The bisprotected gem-diamines have been fully characterized by IR, 1 H NMR, 13 C NMR as well as by mass spectrometry.