Abstract
The 4-methoxy-2, 3, 6-trimethylbenzenesulfonyl (Mtr) group was introduced as a protecting group for the amino function, especially the ε-amino function of lysine, and the imidazole ring of histidine. The Nε-Mtr group was removable by dilute methanesulfonic acid-containing trifluoroacetic acid-thioanisole, but was stable to trifluoroacetic acid or catalytic hydrogenation. The Nlm-Mtr group was removable by trifluoroacetic acid-dimethylsulfide or 1-hydroxybenzotriazole, but was more stable than the Nlm-Tos or the Nlm-Mbs group with triethylamine. To examine the usefulness of the Mtr group as a protecting group for use in peptide synthesis, mastoparan X and chicken gastrin releasing peptide (c-GRP) were synthesized, and this group was found to be very convenient for general solution synthesis. In particular, the introduction of Lys (Mtr) made possible a new strategy in peptide synthesis.
