Benzoic substituted, auxins

Through a comparison of the insecticidal and toxicological data, structure-activity theories were developed which provided a means for the synthesis of safer compounds. A similar approach was used in the 2,4-D area. All manner of substituted phenoxy and benzoic acids and their derivatives were prepared. As a result, much was learned about the structural relationships for the auxin type action. This analog synthesis procedure has often been called "me too chemistry". The patent literature abounds with examples of such a strategy tried on almost everything that has shown a modicum of biological activity. 

Four main classes of natural and synthetic plant growth substances are distinguished 1) The 3-indolylacetic acid derivatives (lAA) and other C-3 substituted indoles, previously known as auxins, induce a pronounced longitudinal growth, stimulate the formation of roots and flowers, the activity of the cambium, and influence fruit ripening and numerous other developmental processes in the plant. In the literature many compounds with different constitutions are also designated as auxins if they have activities similar to those of lAA. These include, e. g., 2-naphthyloxyacetic acid, benzoic acid, phenoxycarboxylic acid derivatives. 

Also in other series of growth substances indications are found that substitutions not compatible with auxin activity may lead to an antiauxin character of the respective compound, as e.g. for benzoic acids and phenoxy-acetic acids substituted in the 4- or 2,6-positions respectively . ... 

Keitt GW, Baker RA (1966) Auxin activity of substituted benzoic acids and their effect on polar auxin transport. Plant Physiol 41 1561-1569 Kende H (1964) Preservation of chlorophyll in leaf sections by substances obtained from root exudate. Science 145 1066-1067... 

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