Copper-Catalyzed Carbonylative Cross-Coupling of Alkyl Iodides and Amines

A general copper-catalyzed carbonylative cross-coupling between amines and alkyl iodides is reported. Using a simple combination of catalytic amounts of copper(I) chloride and N,N,N’,N”,N”-pentamethyldiethylenetriamine in the presence of sodium hydroxide under carbon monoxide pressure, a broad range of alkyl iodides and amines can be efficiently coupled to the corresponding amides that are obtained in good to excellent yields. Notable features of this process – the first one relying on a base metal catalyst – include the availability and low cost of the catalytic system, its successful use with primary, secondary, tertiary alkyl iodides and all classes of amines – with no or limited competing nucleophilic substitution without CO incorporation – as well as its efficiency with complex alkyl iodides and amines. Mechanistic studies demonstrated that a radical pathway is operative and the key role of CO.     

Photo-Oxidizing Ruthenium(II) Complexes with Enhanced Visible-Light Absorption and G-quadruplex DNA Binding Abilities

Photosensitizers that gather high photo-oxidizing power and strong visible-light absorption are of great interest in the development of new photo-chemotherapeutics. Indeed, such compounds constitute attractive candidates for the design of type I photosensitizers that are not dependent on the presence of oxygen. In this paper, we report on the synthesis and studies of new ruthenium(II) complexes that display strong visible-light absorption and can oxidize guanine residues under visible-light irradiation, as evidenced by nanosecond transient absorption spectroscopy. The reported compounds also tightly bind to G-quadruplex DNA structures from the human telomeric sequence (TTAGGG repeat). The kinetic and thermodynamic parameters of the interaction of these Ru(II) complexes with G-quadruplex and duplex DNA were studied thanks to luminescence titrations and bio-layer interferometry measurements, which revealed higher affinities towards the non-canonical G-quadruplex architecture. Docking experiments and non-covalent ionic analysis allowed us to gain information on the mode and the strength of the interaction of the compounds towards G-quadruplex and duplex DNA. The different studies emphasize the substantial influence of the position and the number of non-chelating nitrogen atoms on the interaction with both types of DNA secondary structures.     

Résolution du problème de Dirichlet pour lʼéquation du Jacobien prescrit via lʼéquation de Monge–Ampère

We give an alternative proof, based on the Monge–Ampère equation, of Dacorogna and Moser?s result (Dacorogna and Moser, 1990) [4] on the solvability with optimal regularity of the Dirichlet problem for the prescribed Jacobian equation.     

Site‐Selective,Modular Diversification of Polyhalogenated Aryl Fluorosulfates (ArOSO2F) Enabled by an Air‐Stable PdI Dimer

Since 2014, the interest in aryl fluorosulfates (ArOSO₂F) as well as their implementation in powerful applications has continuously grown. In this context, the enabling capability of ArOSO₂F will strongly depend on the substitution pattern of the arene, which ultimately dictates its overall function as drug candidate, material, or bio‐linker. This report showcases the modular, substrate‐independent, and fully predictable, selective functionalization of polysubstituted arenes bearing C?OSO₂F, C?Br, and C?Cl sites, which makes it possible to diversify the arene in the presence of OSO₂F or utilize OSO₂F as a triflate surrogate. Sequential and triply selective arylations and alkylations were realized within minutes at room temperature, using a single and air‐stable Pd^I dimer.     

Synthesis and Molecular Editing of Callyspongiolide,Part 1: The Alkyne Metathesis/trans-Reduction Strategy

A path-scouting investigation into the highly cytotoxic marine macrolide callyspongiolide is reported that capitalizes on the selective formation of the C10−C11 alkene site. While the closure of the macrocycle by ring closing alkyne metathesis (RCAM) with the aid of a molybdenum alkylidyne complex was high yielding, the envisaged semi-reduction of the cycloalkyne to the corresponding E-alkene proved challenging. The reasons are likely steric in origin, in that the methyl branches on either side of the alkyne seem to prevent effective coordination of the substrate to the ruthenium catalyst, which must carry a bulky Cp* ligand to ensure high trans-selectivity. This notion is supported by the preparation of a callyspongiolide analogue, in which the two methyl groups in question are excised; its formation by RCAM followed by trans-hydrostannation/proto-destannation was straightforward. In parallel work the formation of the fully functional building block 54 showed that the presence of an unprotected -OH group allows even hindered substrates to be processed: the protic group adjacent to the triple bond engages with a chloride ligand on the ruthenium catalyst in hydrogen bonding and hence assists in substrate binding. Moreover, the preparation of an alkynylogous callyspongiolide analogue is described.     

Dynamic load balance applied to particle transport in fluids

This work presents a parallel numerical strategy to transport Lagrangian particles in a fluid using a dynamic load balance strategy. Both fluid and particle solvers are parallel, with two levels of parallelism. The first level is based on a substructuring technique and uses message passing interface (MPI) as the communication library; the second level consists of OpenMP pragmas for loop parallelisation at the node level. When dealing with transient flows, there exist two main alternatives to address the coupling of these solvers. On the one hand, a single-code approach consists in solving the particle equations once the fluid solution has been obtained at the end of a time step, using the same instance of the same code. On the other hand, a multi-code approach enables one to overlap the transport of the particles with the next time-step solution of the fluid equations, and thus obtain asynchronism. In this case, different codes or two instances of the same code can be used. Both approaches will be presented. In addition, a dynamic load balancing library is used on the top of OpenMP pragmas in order to continuously exploit all the resources available at the node level, thus increasing the load balance and the efficiency of the parallelisation and uses the MPI.     

Mixtures of foam and paste: suspensions of bubbles in yield stress fluids

We study the rheological behavior of mixtures of foams and pastes, which can be described as suspensions of bubbles in yield stress fluids. Model systems are designed by mixing monodisperse aqueous foams and concentrated emulsions. The elastic modulus of the bubble suspensions is found to depend on the elastic capillary number $\textit{Ca}_{_G}$ , defined as the ratio of the paste elastic modulus to the bubble capillary pressure. For values of $\textit{Ca}_{_G}$ larger than $\simeq 0.5$ , the dimensionless elastic modulus of the aerated material decreases as the bubble volume fraction $\phi $ increases, suggesting that bubbles behave as soft elastic inclusions. Consistently, this decrease is all the sharper as $\textit{Ca}_{_G}$ is high, which accounts for the softening of the bubbles as compared to the paste. By contrast, we find that the yield stress of most studied materials is not modified by the presence of bubbles. This suggests that their plastic behavior is governed by the plastic capillary number $\textit{Ca}_{\tau_y}$ , defined as the ratio of the paste yield stress to the bubble capillary pressure. At low $\textit{Ca}_{\tau_y}$ values, bubbles behave as nondeformable inclusions, and we predict that the suspension dimensionless yield stress should remain close to unity, in agreement with our data up to $\textit{Ca}_{\tau_y}=0.2$ . When preparing systems with a larger target value of $\textit{Ca}_{\tau_y}$ , we observe bubble breakup during mixing, which means that they have been deformed by shear. It then seems that a critical value $\textit{Ca}_{\tau_y}\simeq 0.2$ is never exceeded in the final material. These observations might imply that, in bubble suspensions prepared by mixing a foam and a paste, the suspension yield stress is always close to that of the paste surrounding the bubbles. Finally, at the highest $\phi $ investigated, the yield stress is shown to increase abruptly with $\phi $ : this is interpreted as a “foamy yield stress fluid” regime, which takes place when the paste mesoscopic constitutive elements (here, the oil droplets) are strongly confined in the films between the bubbles.     

Age-related delay in information accrual for faces: Evidence from a parametric, single-trial EEG approach

Background  

In this study, we quantified age-related changes in the time-course of face processing by means of an innovative single-trial ERP approach. Unlike analyses used in previous studies, our approach does not rely on peak measurements and can provide a more sensitive measure of processing delays. Young and old adults (mean ages 22 and 70 years) performed a non-speeded discrimination task between two faces. The phase spectrum of these faces was manipulated parametrically to create pictures that ranged between pure noise (0% phase information) and the undistorted signal (100% phase information), with five intermediate steps.