Synthesis of Nπ-2-Adamantyloxymethylhistidine, His(Nπ-2-Adom), and Its Evaluation for Peptide Synthesis.

N π -2-Adamantyloxymethylhistidine, His(Nπ-2-Adom), is prepared and successfully applied to the synthesis of thyrotropin-releasing hormone (TRH) in combination with tert-butyloxycarbonyl (Boc) as the Nπ-protecting group. This new protecting group suppressed racemization during peptide synthesis and exhibited high solubility in organic solvents.