CHEMISTRY AND STRUCTURE OF GANEFROMYCIN

Ganefromycins are antibiotics produced by Streptomyces lydicus sp. tan zanius having commercial potential as performance enhancement agents f or livestock. Ganefromycins are related to the elfamycin family of ant ibiotics but contain several unique chemical features which are the so urce of novel and unexpected chemistry. Reactions under mildly basic c onditions resulted in the interconversion of ganefromycins alpha (1) a nd beta (2) by a 1,2-acyl migration. Strong base causes elimination of a trisaccharide whose structure was solved by single-crystal X-ray di ffraction analysis of the triacetate of the reduced ring-opened triol. Ammonolysis yields the same rearranged product from either 1 or 2. Ev idence is provided for the mechanism of this rearrangement involving e limination of the saccharide to form a transient alpha,beta-unsaturate d carbonyl, Michael addition of ammonia, and intramolecular transacyla tion. Ozonolysis and acidic methanolysis were employed to obtain simpl ified compounds for structure determination. Ganefromycin beta fragmen ts in warm acetic acid solution, releasing the long-chain amino acid. C-13 NMR data with assignments are provided for the degradation produc ts.