The 2, 2, 2-trichloroethoxycarbonyl (Troc) group attached at the N in function of tryptophan by acylation with Troc-Cl in the presence of a catalytic amount of tetra-n-butylammonium hydrogensulfate can be quantitatively removed either by cadmium dust in acetic acid or under basic conditions, eg, hydrazine hydrate and NaOH, but is resistant to strong acidic conditions.