Diterpenes from Araucaria imbricata

Clark, James (1962) Diterpenes from Araucaria imbricata. PhD thesis, University of Glasgow.

Abstract

The introductory section of the thesis contains a brief account of some of the important steps in the structural elucidation of the known bicyclic diterpenes, followed by some present ideas on diterpene biogenesis. The theoretical and experimental sections are concerned with the isolation and structural determination of natural products from the bark of Araucaria Imbricata, the Chilean Pine tree, known in Britain as the 'Monkey Puzzle' Extraction of the powdered bark with light petroleum gave a gummy extract which was separated into neutral and acidic fractions. The neutral fraction contains ceryl alcohol, beta-sitosterol,and a new diterpene diol, labd-8(20)-en-3beta,15-diol. The elucidation of the structure of this compound takes up the major part of the thesis. Dehydrogenation of the diol with selenium gave 1,2,5-trimethylnaphthalene, showing it to be bicyclic and of the labdane type. The position of the exocyclic double bond and the stereochemistry of the side chain were established by comparison of the molecular rotational differences of several derivatives with similar compounds in the labdanolic acid series. The stereochemistry of the ring junction was shown to be normal by optical rotatory dispersion measurements. The positions of the hydroxyl groups were established by mass spectral, optical rotatory dispersion, and chemical evidence, but an attempt to convert the diol to a known compound, dihydrocativic acid, did not lead to the isolation of the product in a pure state. The neutral fraction was also shown to contain 3beta-hydroxylabd-8(20)-en-15-al since lithium aluminium hydride reduction gave the diol,but this aldehyde could not be purified for characterisation. The acidic fraction contains the new diterpene acid 3beta-hydroxylabd-8(20)-en-15-oic acid which is also reduced to the diol with lithium aluminium hydride.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Organic chemistry
• Date of Award: 1962
• Depositing User: Enlighten Team
• Unique ID: glathesis:1962-79454
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 05 Mar 2020 09:31
• Last Modified: 05 Mar 2020 09:31
• URI: https://theses.gla.ac.uk/id/eprint/79454