The Kaurane-Phyllocladane Series

The Kaurane-Phyllocladane Series.— There have been several chemotaxonomic studies on the distribution of diterpene hydrocarbons amongst the Podocar-paceae, Sciadopityaceae, and Taxodiaceae. A more detailed study of eighty-four specimens of Cryptomeria japonica reveals an infra-species variation in hydrocarbon production. Thus although sixty-six trees produced (—)-kaurene, nine produced phyllocladene of the opposite stereochemical series. Indeed, even trees from the same seed source were not uniform in their hydrocarbon production. This paper also records a warning of the facile isomerisation of kaurene and phyllocladene into their A -isomers. 

Treatment of 2a-hydroxybeyeran-15,16-epoxide with lead tetra-acetate leads to a 2- 20 ether. The presence of a 15,16-epoxide permitted isomerisation to the kaurene series. The 2o,3a-dioIs afford a 3-mono-toluene-p-sulphonate which undergoes elimination to form the 2-ketone. 

7/3-Hydroxy-(—)-kaur-16-en-19-oic acid and 6j ,7 -dihydroxy-( —)-kaur-16-en-19-oic acid have been prepared for investigation into the biosynthesis of gibberellic acid, the former by Meerwein-Ponndorf reduction of the 7-ketone and the latter by osmylation of a 6,7-olefin. 

Fujita, T. Fujita, M. Taoka, H. Katayama, and M. Shibuya, Tetrahedron Letters, 

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