OCTACIDOMYCINS, .3. SYNTHETIC STRUCTURAL ANALOGS FROM C-5-UNITS

The total synthesis of an isoprenoid-like analogue (2) of octacidomycin (1), a novel oligocarboxylic acid antibiotic, is described. Starting from 3 (Scheme 1) and the tetraethylester of 1,11-dibromoundecane-4,4,8,8,-tetracarboxylic acid (6) as a key compound systematical fragment condensations lead to the pentadecacarboxylic acid 12 and hence to the 1,3,7,11,15,19,23,27-heptacosane-octacarboxylic acid 2. This contains regularly connected C-5- instead of C-7-units and shows contracted distances between the acid groups. The newly developed synthesis yields a hitherto unknown type of oligocarboxylic acids and some useful intermediates with one or two terminal vinylic functions (13-15).