Recherches dans le domaine des substances de croissance

Abstract

After the isolation of auxins in the Laboratory of Organic Chemistry of the University of Utrecht, the possibilities of synthesising these substances have been investigated there. The work presented in this dissertation was aimed at the synthesis of compounds that, concerning the constellation of functional groups, could be model substances of auxin-a, auxin-b or their lactones. Firstly, properties are discussed of a compound that, like the auxins, has an allyl alcohol group. According to previous experiments in our laboratory it was suggested that this compound should suffer a spontaneous allylic transposition, resulting in auto-inactivation of auxin. New experiments show that the model substance does not change in the absence of oxygen. Secondly, a general method is indicated for the synthesis of lactones of beta-keto-gamma-oxy carboxylic acids by the Reformatsky reaction. Thirdly, the synthesis of a series of compounds that show a certain structural analogy with the auxins is described. The structure of these compounds is inferred from the synthetic pathway and analytical data. The structural formulas in question are confirmed by ultraviolet spectral analysis. In particular, the synthesis of delta-(cyclopentenyl-1)-delta-oxy-beta-ketopentanoic acid lactone should be mentioned. With regard to the constitution, this compound only differs from auxin-b lactone by the absence of two secondary butyl groups from the cyclopentene ring. This indicates a possible pathway to a complete synthesis of auxin-b lactone. The compounds discussed above all lack activity in the Avena-test

In the second part of this thesis a new isolation of biotin from egg yolk is described. The crystals obtained turn out to be identical to the product isolated by American authors from liver and milk. In previous experiments, the degradation of biotin from egg yolk gave rise to an as yet unknown substance, alpha-isopropyl-beta-sulphopropionic acid, the constitution of which has been confirmed by synthesis. The structural formula of biotin, proven afterwards by American authors, cannot explain the formation of alpha-isopropyl-beta-sulphopropionic acid. Possible sources of this discrepancy are discussed.