Gibberellin from gibberellic acid

The unsaturated ketone (70) is a catabolite of gibberellin A29. It has been prepared107 from gibberellic acid. The 2-position of gibberellins is metabolically reactive and consequently the biological activity of a number of 2-substituted... 

Gibberellin Aj2 aldehyde 4.116) is the first detectable gibbane intermediate in G. fujikuroi. From it a web of oxidation reactions leads through to various gibberellins including gibberellic acid 4.117) which also involves loss of the C-10 methyl group, probably via a carboxy-function [103-106]. 

These compounds were originally isolated from a parasitic fungus that causes excessive leaf elongation in nee plants. The mechanisms and applications of this group of compounds are described in Gibberellic Acid and Gibberellin Plant Growth Hormones. 

Gibberellic acid is obtained most readily pure and in quantity and knowledge of the chemistry of the gibberellins comes largely from study of the chemistry of... 

Fractions brought off the column with elutants ranging from 80% acetone in water to pure acetone (108 mg. of solids) contained most of the biologically active material. The solids in these fractions showed a yellow fluorescence when dissolved in concentrated sulfuric acid. Gibberellic acid (V) shows a similar fluorescence under these conditions, whereas gibberellin A4 and other fungal gibberellins do not. 

A major factor which could not be evaluated in this study is the ratio between residual extraneous gibberellic acid and endogenous gibberellins. Because of the weight increase of the plants from the time of application of the gibberellic acid to harvest, these natural levels in many cases might be comparable with the artificial levels. This phase has since been studied (4). 

The diazo ketone methodology has provided a general route to gibberellins. Thus treatment of the diazo ketone 1, obtained from 1,7-dimethoxynaphthalene, with TFA resulted in the tricyclic dienedione 2, which was converted in a few steps to 3, which contains the B, C, and D rings of gibberellic acid (4).2... 

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