Investigation of artificial malonyl group carriers and multifunctional cyclic scaffolds towards the mimicry of PKS

• Main Author: Martinez Lozano, Luis
• Published: University of East Anglia 2015
• Subjects: 540
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.656144

This thesis presents a new convenient method for the synthesis of malonic acid half esters and thioesters under solvent-free conditions. The relative acidity of a broad variety of MAHOs and MAHTs has been estimated by an innovative and simple method based on the determination of observed rate constants from hydrogen-deuterium exchange experiments of malonates. The results obtained from kinetic experiments allowed us to select the more suitable artificial malonyl carriers in decarboxylative aldol-type condensations. In the second part of the thesis, the first example of a base and metal -free decarboxylative aldol condensation is described. Three different catalytic systems have been successfully employed to carry out mild condensations between malonates and aldehydes. One of these catalytic systems involves the first use of an antibiotic (valinomycin) in the catalysis of decarboxylative aldol condensations. In the last part of the thesis, a new versatile and regioselective method to obtain monofunctionalised calix[4]arenes blocked in a cone conformation is described. A broad range of monoarmed calix[4]arenes have been synthesised and the properties of some of these calix[4]arenes studied. In addition, a simple method for the preparation of multi functional calix[4]arenes blocked in the cone conformation has been developed, using a procedure based on the discovery of new reaction conditions for efficient Cannizzaro reactions of diformyl calix[4]arenes. Finally, the synthesis of a bio-inspired bifunctional mercapto-calix[4]arene has been carried out, in order to mimic part of the active site of a PKS. The new mercapto-calix[4]arene prepared, which carries two sulfhydryl groups in the upper rim, has been successfully loaded with two malonyl molecules and employed to mimic the condensing function of PKS.