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International audience; Les structures tridimensionnelles polycycliques sont présentes dans un nombre important d’architecturesmoléculaires complexes, naturelles ou synthétiques, présentant un vaste champ d’applications biologiques. Ledéveloppement de processus domino qui génèrent la formation de plusieurs liaisons en une seule opération estune approche simple et efficace pour accéder rapidement à des édifices présentant à la fois une grande diversitéstructurale et une complexité moléculaire intéressante. Lorsqu’elles emploient des promoteurs non toxiques, cestransformations répondent par ailleurs au principe d’une chimie plus respectueuse de l’environnement en appliquantle concept d’économie d’atomes et d’étapes et en évitant l’isolement et la purification des intermédiaires.Dans ce contexte, cet article présente la construction de molécules organiques complexes à partir d’aldéhydesinsaturés et différentes réactions de polycyclisation qui ont permis d’obtenir très rapidement une variété denouveaux motifs structurels.

International audience; Photochemistry is a tremendous research field offering many synthetic possibilities to the chemists. Breakthroughs in this area have been notably driven by the implementation of new classes of photocatalysts. Within this context, Bodipy (Borondipyrromethene) dyes possess attractive chemical and physical features such as their modularity, strong absorption under visible light irradiation, good thermal and photochemical stabilities and high fluorescence quantum yields. As such, this class of compounds has found widespread applications in functionalized materials, biology, medicine or organic chemistry. From an organic-synthetic point of view, excited states of Bodipy dyes have been harnessed in electron and energy transfer reactions. This minireview collates the relevant literature on the applications of these catalysts in synthetic photochemistry and provides some perspectives of this research area.

The production of lipids by microalgae is widely studied, especially to find the best bioprocess operating conditions and optimize the productivity of the targeted product. In this context, being able to monitor online the evolution of the lipid concentration is a great advantage regarding the control and/or the optimization of the production. Yet, most non-invasive analyses hit a brick wall on the interference of the lipid signal with the ubiquitous water of the culture medium. This article shows how a compact NMR spectrometer connected to a photobioreactor can circumvent this drawback and measure, in real-time and in a non-invasive manner, the total lipid concentration, and that directly on the entire cells grown in their culture medium. The water signal could be enough-selectively removed using the W5 version of the WATERGATE pulse sequence. The NMR signal nicely correlates (R² > 0.99) with the offline FAME (Fatty Acid Methyl Ester) total lipid analysis as performed by GC-FID (Gas Chromatography coupled to Flame Ionization Detector) within limits of detection and quantification of respectively 9 and 30 mg.L−1. The lipid specific signal appears also quite robust regarding the dissolved dioxygen, making the benchtop NMR spectroscopy an appropriate universal device for the online monitoring of lipids produced in bioprocesses.

International audience; In the past decade, the field of visible-light mediated photocatalysis has been particularly thriving by offering innovative synthetic tools for the construction of functionalized architectures from simple and readily available substrates. One strategy that has been of interest is energy transfer catalysis which a powerful way of activating a substrate or an intermediate by using the combination of light and a relevant photosensitizer. This review deals with recent advances in energy transfer catalysis applied to phenols which are ubiquitous in chemistry both as starting materials and as high-added value products. Processes involving energy transfer from the excited photosensitizer to ground state oxygen and to phenol-containing substrates will be described.

International audience; We report herein a new catalytic strategy towards asymmetric photooxygenation of -dicarbonyl compounds. Our method is based on the synthesis of a bifunctional photosensitizer composed of a quinine organocatalyst grafted to a iodo-BODIPY framework capable of generating singlet oxygen. The quinine moiety serves both to interact with the substrate for promoting photooxygenation and to deactivate singlet oxygen in the absence of substrate. The bifunctional photosensitizer prepared was subsequently applied in the asymmetric oxygenation of a series of -dicarbonyl compounds under green light irradiation. Control experiments and kinetic analyses were carried out to shed the light on the mechanism.

Herein, we report a short and facile stereoselective route to ergoline derivatives. The key steps are a one-pot Friedel-Crafts alkylation/Michael addition sequence which, in the absence of chiral ligands, affords the trans-trans-stereoisomer in 44% yield as a racemate. Screening of a range of chiral bisoxazoline ligands allowed this sequence to proceed in 42-55% yields (six examples), with up to 99% ee. This approach allows for the first time, substitution at the C-4-position and the introduction of 3 chiral centres in one pot. An interesting, base-mediated conversion of the trans-trans-stereoisomer to the cis-cis-stereoisomer was discovered and both stereoisomers were characterized by X-ray crystallography.

International audience