Asymmetric synthesis of the four stereoisomers of 5-deoxystrigol

Two approaches to the strigolactone tricyclic lactone skeleton 2 were investigated using ketene/ketene-iminium cycloaddition to olefins. Finally, the first enantioselective access to the four stereoisomers of 5-deoxystrigol 1 is reported using an intramolecular [2+2] cycloaddition of homochiral ketene-iminium salts 5. Very high asymmetric control was achieved with C-2 symmetric pyrrolidines as chiral auxiliary.     

More compact invariant manifolds appearing in the non-linear coupling of oscillators

Near partially elliptic rest points of generic families of vector fields or transformations, many types of normally hyperbolic invariant compact manifolds can appear, diffeomorphic to intersections of quadrics. To cite this article: M. Chaperon et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006).     

Photometrische Bestimmung des Mangans mit Dithiocarbaminaten

Zusammenfassung Kleine Mengen Margan können durch Extraktion der innerkomplexen Mangan(III)-dithiocarbaminate mit Chloroform und nachfolgende Photometrierung der braunvioletten Extrakte schnell und genau bestimmt werden. Nur wenige Elemente stören. Sie können vorher durch Extraktion rasch und quantitativ abgetrennt werden.     

Procedure of test to compare the tail indices

We propose a test procedure which compares the extreme value indices of two samples with heavy tail distributions. On a theoretical point of view, we adopt the minimax nonparametric point of view. We exhibit the separating rate between the null hypothesis and the alternative of our procedure. Next, we present a data driven test methodology and we evaluate its performance thanks to an extensive simulation study. As a practical real-life application, we compare the risk behaviors of a panel of different financial data.     

The remarkable effect of the 7-substituent in the diastereoselective oxidative rearrangement of indoles: asymmetric synthesis of 3,3-disubstituted oxindoles

The nature of the 7-substituent has a remarkable effect on the diastereoselectivity of the oxidative rearrangement of indole-2-carboxamides derived from (S)-2-methoxymethylpyrrolidine into chiral 3,3-disubstituted oxindoles.     

Nature-inspired dimerization as a strategy to modulate neuropeptide pharmacology exemplified with vasopressin and oxytocin

Vasopressin (VP) and oxytocin (OT) are cyclic neuropeptides that regulate fundamental physiological functions via four G protein-coupled receptors, V_1aR, V_1bR, V₂R, and OTR. Ligand development remains challenging for these receptors due to complex structure–activity relationships. Here, we investigated dimerization as a strategy for developing ligands with novel pharmacology. We regioselectively synthesised and systematically studied parallel, antiparallel and N- to C-terminal cyclized homo- and heterodimer constructs of VP, OT and dVDAVP (1-deamino-4-valine-8-d-arginine-VP). All disulfide-linked dimers, except for the head-to-tail cyclized constructs, retained nanomolar potency despite the structural implications of dimerization. Our results support a single chain interaction for receptor activation. Dimer orientation had little impact on activity, except for the dVDAVP homodimers, where an antagonist to agonist switch was observed at the V_1aR. This study provides novel insights into the structural requirements of VP/OT receptor activation and spotlights dimerization as a strategy to modulate pharmacology, a concept also frequently observed in nature.

Structural and pharmacological study of parallel, antiparallel and N- to C-terminal cyclized homo- and heterodimers of vasopressin and oxytocin. This study spotlights dimerization as a strategy to modulate the pharmacology of neuropeptides.     

Water-Soluble Fe(II) Complexes for Theranostic Application: Synthesis,Photoacoustic Imaging,and Photothermal Conversion

Significant effort focused on developing photoactivatable theranostics for localized image guided therapy of cancer by thermal ablation. In this context iron complexes were recently identified as photoactivatable theranostic agents with adequate biocompatibility and body clearance. Herein, a series of Fe^II complexes bearing polypyridine or N-heterocyclic carbenes is reported that rely on rational complex engineering to red-shift their MLCT based excited-state deactivation via a straightforward approach. The non-radiative decay of their MLCT upon irradiation is exploited for theranostic purposes by combining both tracking in photoacoustic imaging (PA) and photothermal therapy (PTT). The influence of structural modifications introduced herein on the solubility and stability of the complexes in biorelevant aqueous media is discussed. The relationship between complexes’ design, production of contrast in photoacoustic and photothermal efficiency are explored to develop tailored PA/PTT theranostic agents.     

Crystalline Amyloid Structures at Interfaces

Laying the groundwork : The interfacial self‐assembly properties of an amyloid peptide were used to develop crystalline nanostructures at air–water interfaces, which were studied by both AFM microscopy and X‐ray diffraction (see image). These structures generate regular arrays of functional groups and pave the way to controlled deposition of inorganic materials like that observed in biomineralization.