Synthesis of GA73 methyl ester, a potent gibberellin-derived antheridiogen from gametophytes of the fern lygodium japonicum

Twenty years of gibberellin researchElectronic supplementary information (ESI) available: functionality patterns for naturally occurring gibberellins (GAn). See http://www.rsc.org/suppdata/np/b0/b007744p/

“…In their seminal work with maize mutants, MacMillan and Phinney 221 demonstrated that GA 1 (162) had the primary role in promoting stem elongation; the same conclusion has since been made for rice, while GA 4 (163) plays an equivalent role in cucumber. 222 Although many other GAs are clearly biosynthetic intermediates or catabolites, it seems reasonable to assume that much of the structural diversity is related to a corresponding diversity of function.…”

“…Alkenoic acids such as 25 may be prepared from gibberellenic acid 142 methyl ester 24 or from 2,19-lactones like 17. 162 Since the isolation of 28, four further ∆ 9(11) -GAs have been isolated, either from Lygodium species or from apple seeds, and their structures confirmed by synthesis. 83,89,96,101…”

The chemistry of gibberellins: an overview

“…102 The correct structure, except for an assignment of stereochemistry as C(9a) instead of the actual C(98) configuration, was proposed in 1959,103 and this last feature was elucidated in 1962 when an X-ray crystallographic study was completed on the bromo ketone derivative ll. 104 This had been obtained by treatment of 1 methyl ester with pyridinium perbromide and involves a Wagner-Meerwein rearrangement of C (12) from C (13) to C (16). A further structure was completed on the 3,13-di-p-bromo benzoate of l106 in the following year, and then in 1983 of 1 itself.106 Further X-ray structures on other GAs have been ob-tained107 and have provided, inter alia, important data on spatial relationships and the shape of the molecule, including the valuable information that the C-ring possesses a boat rather than the normally preferred chair conformation.…”

“…The effort to obtain sufficient material may therefore be considerable, e.g. 38 mg of GA32 (12) was accumulated from the immature seeds obtained from 1 ton of unripe peaches,55 while 14 mg of GA19 (13) was obtained from the aqueous washings of 44 ton of bamboo shoots. 41 In many cases it has only been practical to obtain nanogram quantities, and after making an educated guess on the basis of mass spectrometry and chromatographic behavior, it is then necessary to seek confirmation by a partial synthesis.…”

Diterpenoids

“…222 In the course of screening marine organisms for antagonists to the platelet activating factor an active compound, chatancin (164), was from a Sarcophyton species. The bromoditerpenes (165) and (166) have been reported224 to be constituents of Sphaerococcus coronopifolius.…”