Studies in terpenoid biosynthesis. Part V. Biosynthesis of rosenonolactone

Abstract

Geranylgeraniol is shown to act as a precursor of rosenonolactone in Tricothecium roseum. Examination of the labelling pattern from [2-³H₂,(4R)-[4-³H, and [5-³H₂,2-¹⁴C]mevalonates has confirmed the 9 → 8 hydride shift and excluded the formation of 1(10)- and 5(10)-double bonds both during the cyclization and rearrangement of the labda-8(17),13(14)-dien-15-ol precursor and in the formation of the lactone ring. Some randomization occurs when labdanes oxygenated at C-19 are incorporated into rosenonolactone by Tricothecium roseum. Desoxyrosenonolactone acts as a precursor of rosenonolactone and rosololactone. Rosenololactone acts only as a precursor of rosenonolactone.