STUDIES ON THE BIOSYNTHESIS OF CLAVULANIC ACID

II. CHEMICAL DEGRADATIONS OF ¹⁴C-LABELLED CLAVULANIC ACID

Abstract

Two chemical degradations of clavulanic acid are described which are useful for locating label in ¹⁴C-clavulanate. In the first, the β-hydroxyethylidene side chain of pbromobenzyl clavulanate is removed by ozonolysis to give pbromobenzyl (2R, 5R)-3, 7-dioxo-4-oxa-1-azabicyclo [3.2.0] heptane-2-carboxylate. The second involves the reaction of pbromobenzyl clavulanate with dibenzylamine in methanol, to isolate the three β-lactam carbons as methyl trans3-(N, Ndibenzyl)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.