CHEMISTRY AND STRUCTURE OF GANEFROMYCIN

Ganefromycins are antibiotics produced by Streptomyces lydicus sp. tanzanius having commercial potential as performance enhancement agents for livestock. Ganefromycins are related to the elfamycin family of antibiotics but contain several unique chemical features which are the source of novel and unexpected chemistry. Reactions under mildly basic conditions resulted in the interconversion of ganefromycins alpha (1) and beta (2) by a 1,2-acyl migration. Strong base causes elimination of a trisaccharide whose structure was solved by single-crystal X-ray diffraction analysis of the triacetate of the reduced ring-opened triol. Ammonolysis yields the same rearranged product from either 1 or 2. Evidence is provided for the mechanism of this rearrangement involving elimination of the saccharide to form a transient alpha,beta-unsaturated carbonyl, Michael addition of ammonia, and intramolecular transacylation. Ozonolysis and acidic methanolysis were employed to obtain simplified compounds for structure determination. Ganefromycin beta fragments in warm acetic acid solution, releasing the long-chain amino acid. C-13 NMR data with assignments are provided for the degradation products.