Studies in terpenoid biosynthesis. Part 30. The acetate and mevalonate labelling patterns of the diterpenoid, aphidicolin

Abstract

The ¹³C n.m.r. spectra of aphidicolin and its derivatives have been assigned. The enrichment and coupling patterns of aphidicolin biosynthesized from [1-¹³C]-, [2-¹³C]-, and [1,2-¹³C₂]-acetate were determined and used to define the constituent isoprene units. The numbers of 2- and 5-mevalonoid hydrogen atoms incorporated into aphidicolin were determined by ³H labelling. The generation of²H–¹³C coupling which was observed in the ²H n.m.r. spectrum of aphidicolin biosynthesized from [4-²H₂,3-¹³C] mevalonic acid, has established the migration of a 9β-hydrogen atom to C-8 during the biosynthesis.