[Side-reactions in peptide synthesis, IV. Charactertzation of C- and C,N-teri-butylated tryptophan derivatives (author's transl)].

Besides Nin-tert-butylated tryptophan derivatives, other tert-butyl-tryptophan analoga are also found as a result of side-reactions accurring during the acidolytic cleavage of protecting groups being based on a tert-butyl moiety. C-mono-substitution could be detected as well as di- and tri-substitution. All these tert-butylated tryptophans could be isolated in a pure form from the tert-butylation mixture either free or as derivatives and could unequivocally be identified in particular by means of mass spectrometry and nuclear magnetic resonance spectroscopy.