
%0 Journal Article
%A Pour, Milan 
%A Kraft-Klaunzer, Petra 
%A Furber, Mark 
%A Mander, Lewis N. 
%A Twitchin, Bruce 
%A Oyama, Naomi 
%A Murofushi,, Noboru 
%A Yamane, Hisakazu 
%A Yamauchi, Tadayuki 
%T Synthesis of New 9,15-Cyclogibberellins from Developing Apple Seeds: Confirmation of Structure for GA<emph tye="8">105</emph> and GA<emph tye="8">108</emph>
%J Australian Journal of Chemistry
%D 1997/06/30
%V 50
%N 4
%P 289-300
%K 
%R https://doi.org/10.1071/C96114
%U https://www.publish.csiro.au/paper/C96114 
%X The structures of two new gibberellins (GA105 and GA108) from developing apple seeds were confirmed as 2&#946;- and 11&#946;-hydroxy-9,15-cyclo-GA9, respectively, by synthesis of their methyl esters (7) and (8); the analogous 1&#945;-, 2&#945;- and 11&#945;-isomers were also prepared, the last two being identified as metabolites of 9,15-cyclo-GA9 (2) formed in feeding experiments with fern prothallia of Lygodium circinnatum. The route to (7) began with the Birch reduction of gibberellic acid (GA3) methyl ester 3,13-dimesylate, thereby removing the oxygen substituents from C3 and C13. A series of iodolactonizations and elimination processes followed by ozonolysis of the 17-methylene group furnished (19) which, on treatment with potassium hydride, underwent intramolecular alkylation to afford the cyclogibberellin (20). Further functional group manipulation then led to (7) via its 2&#945;-epimer (23). The previously prepared 11&#946;-bromocyclogibberellin (28) was also subjected to a series of functional group manipulations and deletions to afford the 11&#945;-hydroxy analogue (33), and thence the 11&#946;-epimer (8) by means of an oxidation/reduction cycle; 1&#945;-hydroxycyclo-GA9 methyl ester (26) was similarly prepared from the methyl ester of the known 1&#946;-epimer (3). 
