Terpenoid chemistry. XV. 1,5-Dimethylcyclodeca-1,5,7-triene, the precursor of geijerene in Geijera parviflora (Lindley)

Abstract

Geijera parviflora leaves which yield geijerene when worked up under the usual conditions of steam-distillation and fractional distillation have been found to contain a new hydrocarbon, Cl₂H₁₈ (pregeijerene), and only a trace of geijerene. The structure of pregeijerene has been shown by degradative and spectral examination to be 1,5-dimethylcyclodeca-1,5,7-triene, the disubstituted double bond having a cis configuration. The hydrocarbon forms a crystalline adduct with silver nitrate and rearranges thermally to yield geijerene.