Studies on the biosynthesis of clavulanic acid. II. Chemical degradations of 14C-labelled clavulanic acid.

Two chemical degradations of clavulanic acid are described which are useful for locating label in 14C-clavulanate. In the first, the beta-hydroxyethylidene side chain of p-bromobenzyl clavulanate is removed by ozonolysis to give p-bromobenzyl (2R, 5R)-3,7-dioxo-4-oxa-1-azabicyclo [3.2.0] heptane-2-carboxylate. The second involves the reaction of p-bromobenzyl clavulanate with dibenzylamine in methanol, to isolate the three beta-lactam carbons as methyl trans-3-(N-N-dibenzyl)amino acrylate. These techniques were used to degrade clavulanic acid derived from fermentations fed with 2-14C-acetate or universally 14C-labelled glycerol. The amount of label retained in the degradation products was in agreement with the distribution of 13C in clavulanic acid derived from 2-13C-acetate, or 1,3-13C2-glycerol, as observed by 13C-NMR.