Towards the total synthesis of amphidinol 3

Amphidinols are intriguing amphiphilic architectures exhibiting a variety of biological actions, including antifungal, hemolytic, cytotoxic and ichthyotoxic activities. These properties derive from the disturbance of the arrangement of the lipid bilayer of the targeted cells. The third member of the family, amphidinol 3 was discovered in 1996 and is, to date, the only amphidinol whose stereochemistry is fully established. The synthesis of the C15-C30 polyol domain, as well as the preparation of the C31-C40 trans-configured tetraydropyran will be discussed throughout this work.(SC - Sciences) -- UCL, 201

Metazachlor traces in the main drinking water reservoir in Luxembourg: a scientific and political discussion

Abstract This discussion is centralized around an incident that took place in the Belgian village Witry the 17th of September 2014. A tractor accident led to the discharge of an aqueous solution of the herbicide metazachlor into the creek Moyémont that further merges into the river Sûre. About 20 km downstream, these waters supply the lake of the Upper-Sûre in Luxembourg, the biggest artificial lake and the main drinking water reservoir in the country. The evolution of the concentration of metazachlor and its metabolite 479M08 was partially tracked down from the river Sûre to the dam situated in the east. At this location, the SEBES drinking water treatment plant has its raw water intake from the lake. After this incident, substantial pollution by the metazachlor breakdown product 479M08 of the lake and of some other groundwater sources in the Grand Duchy was revealed due to a strong monitoring program that was started by the national water authority (AGE). This was for example the case in the SEBES groundwater resource Scheidhof close to Luxembourg City. There is also the reason to assume that contamination by 479M08 existed already in the lake before the incident in Witry, certainly due to agricultural activity. In the second part of this discussion, these perceptions are placed in their appropriate political context. Indeed, the quality of groundwater and drinking water is strongly regulated in the European Union and in Luxembourg. Compound 479M08, for instance, is submitted to a maximum parametric value of 0.1 µg/L in Luxembourg. Several short- and longtime political measures had to be taken to guarantee the wholesomeness of the water from a legal point of view

Sexual dimorphism and sex pheromone detection in Aphidoletes aphidimyza

Sexual dimorphism, particularly at the level of sensory and locomotor organs, is usually attributed to sexual selection. Antennae are notably developed in males of species that need to detect a sex pheromone at low concentration or at long distance. In addition to their role in intrasexual selection, antennae can be seen as important ornaments in intersexual selection. Antennae of Aphidoletes aphidimyza are clearly sexually dimorphic (males have longer antennae than females, with highly developed sensilla) while females emit a sex pheromone for mating. Males with longer and more symmetrical antennae than others could be more successful in reaching the source of sex pheromone, especially if they can fly properly. A morphometric study was first conducted, to apprehend the variability of antennae, wings and tibias in lab conditions. The length of the antennae of male A. aphidimyza is impressive and the right antenna is longer than the left antenna. Secondly, choice experiments were conducted in a Y-shaped olfactometer with males of A. aphidimyza facing the sex pheromone. The relationship between choice patterns and morphology of males was then studied, but no link was found between the morphology of males and their behaviour while exposed to the sex pheromone, although males were indeed attracted by the olfactometer arm containing the sex pheromone

Total synthesis of (−)-cleistenolide and formal synthesis of herbarumin I via a diastereoselective modulable allylation

A modulable tin based allylation method for the synthesis of 1,2,3-triols is described. The optimization of the reaction was aided by 1H and 119Sn low temperature NMR spectroscopic investigations, which support the formation of two cyclic intermediates after transmetallation. Depending on the nature of the Lewis acid, either syn/anti or anti/syn configured triols could be obtained with good stereocontrol. To demonstrate the value of this methodology and the resulting scaffolds, they were used to install the signature triol motifs of (−)-cleistenolide and of herbarumin I