Stereoselective syntheses of semichemicals : Applications in ecological chemistry

Abstract: This thesis describes the syntheses of semiochemicals and their applications in the development of control methods for pest insects. The compounds synthesized are divided into three groups: 1) Lepidoptera pheromones; 2) methyl substituted chiral pheromones and 3) aphid pheromones.Different purification techniques have been explored in order to provide > 99% pure semiochemicals for field tests. Examples of the techniques are uses of urea inclusion complexes, argentum chromatography, low temperature crystallization and what we call the Baeckström isolation technique.Iridoids have been produced in a synthetic strategy including an intramolecular enal-enamine [4+2] cycloaddition, a dynamic acetylation and an enantioselective transesterification mediated by a lipase from Pseudomonas cepacia. The use of chiral auxiliaries to perform the intramolecular [4+2] cycloaddition has also been investigated. A useful asymmetric route to iridoids has been developed.