Studies on macrocyclic lactone antibiotics. VI. Skeletal structure of copiamycin.

Abstract
The skeletal structure of copiamycin (C54H95N3O17), a potent antifungal antibiotic, was determined from the physicochemical properties of this compound and of its degradation products. This compound consists of a 32-membered polyhydroxy lactone ring, an .alpha.,.beta.-unsaturated ester group and a side chain with a disubstituted guanidine moiety as its terminal. One of the hydroxyl groups (presumably at C-19) forms a hemiketal ring with the keto group at C-15, and another (at C-21 or C-23) forms a hemiester with a malonic acid moiety.