[The synthesis of motilin, I: Preparation of the sequence fragments 9 - 22 of [13-norleucine]motilin and [13-leucine]motilin (author's transl)].

The syntheses of two suitably protected tetradecapeptides corresponding to the sequences 9 - 22 of [13-norlecucine] motilin [H-Glu(OBut)-Leu-Gln-Arg(HBr)-Nle-Glu(OBut)-Glu(OBut)-Lys(Boc)-Glu(OBut)-Arg(HBr-Asn-Lys(Boc)-Gly-Gln-OBu] and [13-leucine] motilin, respectively, are described. The two building blocks for the total syntheses of the motilin analogs were obtained by fragment-condensation of smaller units, prepared by stepwise procedure and corresponding to the sequences 18 - 22, 14 - 17, 12 - 13 (norleucine- and leucine-derivatives) and 9 - 11.