Abstract:
This thesis describes Further studies on the utilisation of
the diterpenoid natural product , 12-hydrxypodocarpa-8,11,13-trim
19-oic acid* (podocarpic acid) (1) . In particular it describes
transformations of the C-ring to give suitable intermediates for the
synthesis of optically active steroids and terpenoids.
An investigation has been carried out on the Birch reduction
of 12-methoxypodocarpa-8,11,13-trien-19-ol (8), and conditions
for the optimum formation of the ketonic products (10) and (12) are
suggested.
The enones (25) and (26) have been synthesised from
12-hydroxypodocarpa-8,11,13-trien-19-oic acid (1) by sequences involving
reduction of the aromatic ring followed by ring C transformations.
Methyl 12-hydroxypodocarpa-8,11,13-trien-19-oate (3) has
been converted in ca. 60% yield to the dextrorotatory C 13 methyl
ether which has then been reduced in good yield to the enone (163).
Potential routes for conversion of the enones (25), (26), and (163)into steroidal analogues are described. Initial steps in the transformation of the C 13 methyl ether(62) into an intermediate (176) suitable for the synthesis of (+)-a-onocerin (80) have been investigated. A preliminary study on the synthesis of the C 14 phenol
(190) or its methyl ether (191) is also reported.
* The numbering system used throughout this thesis is that proposed
by J.W. Rowe (personal communication to Professor R. C. Cambie) in "The Common and Systematic Nomenclature of Cyclic Diterpenes",
3rd Revision, Oct. 1966, to be submitted to the IUPAC Commission on Organic Nomenclature (see page 144)