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

In order to elucidate the structure of natural polymyxin B 1 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 B 1 in view of its reduced antibacterial activity and different optical rotatory power.