Catalytic tritiation of splenopentine and diacetylsplenopentine via the DI-iodo-tyrosine derivatives

Tritium labelled splenopentine (Arg-Lys-Glu-Val-Tyr-OH) and diacetylsplenopentine (Nα-ac-Arg-Nε-ac-Lys-Glu-Val-Tyr-OH) were prepared by the catalytic dehalotritiation of the corresponding diiodopeptides obtained by ICl-iodination. Under conditions which proved to be optimal in foregoing model deuterations, a specific radioactivity of about 90% of the theoretical one was achieved. The labelling result was influenced noticeably by a transfer of solvent hydrogen directly to the substrate analogously as found in the dehalodeuterations of simple amino acid derivatives. (author)