Enduracidin, a New Antibiotic. VIII. Structures of Enduracidins A and B

From the structural investigation of acidic products obtained by hydrolysis of enduracidins and tetrahydroenduracidins, 10-methylundeca-2 (cis)-4 (trans)-dienoic acid (V) and (+)-10-methyldodeca-2 (cis)-4 (trans)-dienoic acid (VI) were found to be constituent of enduracidins A and B, respectively. Consequently, the structural difference between enduracidins A and B was proved to be present in their unsaturated fatty acid moieties, and their full structures were assumed to be as shown in Fig. 10.