Synthesen in der Polymyxin-Reihe. 4. Mitteilung. Synthese des cyclischen Decapeptids 8γ

In order to elucidate the structure of natural polymyxin B1 the cyclic decapeptide 8 γ(V, Fig. 3, with 8 amino acids in the ring and the side chain attached in γ-position) has been synthesized. This is one of the four possible structures deduced for the natural product by the usual degradation methods. The cyclic decapeptide 8 γ appears not to be identical with polymyxin B1 in view of its reduced antibacterial activity and different optical rotatory power.