Tandem <i>N</i>‑Alkylation/Vinylogous Aldol Reaction of β,γ-Alkenyl α‑Iminoester

This report describes a highly regioselective tandem <i>N</i>-alkylation/vinylogous aldol reaction of β,γ-alkenyl α-iminoesters. The sulfur group improves the regioselectivity of the directed vinylogous aldol reaction, providing a new synthetic method of 3-amino-2-pyrones

La diversité des formes d'habitat organisé dans la Grande Couronne francilienne : essai de typologie des ensembles d'habitat groupé

Document de travail provisoire, à paraître dans Les cahiers de l'IAU-IdFLes périphéries des grandes métropoles offrent aux visiteurs des paysages rapidement reconnaissables... Nombre de ces opérations sont produites dans le cadre d'opérations " groupées " par des promoteurs qui en ont intégré les différentes étapes. Elles apparaissent comme une "image-type" de l'étalement urbain et sont souvent "accusées" d'uniformiser les paysages et les types d'espaces périurbains. Deux éléments semblent favoriser la standardisation des formes produites : la concentration de l'offre au sein de quelques très grands groupes de promotion immobilière, et la production d'ensembles pavillonnaires de types standardisés, propres aux différents types de promoteurs. Cette logique de " marque " est appréhendée ici par la réalisation d'une typologie des ensembles pavillonnaires produits dans la Grande Couronne francilienne

Regioselective Tandem <i>N</i>‑Alkylation/<i>C</i>‑Acylation of β,γ-Alkynyl α‑Imino Esters

A new synthesis of α-quaternary alkynyl amino esters and allenoates was developed utilizing umpolung <i>N</i>-addition to β,γ-alkynyl α-imino esters followed by regioselective acylation. The reaction exhibits broad substrate generality and unique regioselectivity. Moreover, synthesis of α-quaternary alkynyl amino esters was also carried out via oxidation of the intermediary enolate followed by alkylation

Hydrophilic Ligand Exchange Induces Improved Upconversion Nanoparticle Incorporation in Dye-Sensitized Solar Cells with Efficiency Exceeding 8% in a Low-Temperature Fabrication Process

We synthesized core–shell upconversion nanoparticles (UCNPs) with a composition of LiYF4:Yb0.2/Er0.02/Ho0.02/Tm0.02@LiYF4:Yb0.2 and incorporated them into the photoanodes of dye-sensitized solar cells (DSSCs) fabricated through a low-temperature process. The as-prepared hydrophobic UCNPs displayed a good protection ability to prevent the ingress of electrolyte but caused cracking in the mesoporous layers. To resolve this issue, we modified the as-prepared UCNPs by performing ligand exchange using 4-aminobenzoic acid (4ABA), transforming the hydrophobic surface into a hydrophilic one. By design of a three-layer structure to prevent electrolyte ingress, the hydrophilic nature of the 4ABA-modified UCNPs enabled better incorporation into the photoanodes. Consequently, the incorporation of 4ABA-UCNPs significantly improved the power conversion efficiency of DSSCs from 6.32 to 8.22%. This enhancement surpassed most reported values in the literature for DSSCs fabricated using a low-temperature process. Importantly, compared to other hydrophilic ligands, the use of 4ABA did not noticeably increase the charge transfer resistance due to its appropriate molecular weight

Synthesis of Dicarboxylic Acids Comprising an Ether Linkage and Cyclic Skeleton and Its Further Application for High-Performance Aluminum Electrolyte Capacitors

Aluminum electrolytic capacitors are essential components in all electronic devices, and it is known that their longevity depends on the performance of their electrolytes. We synthesized dicarboxylic acids having ether bonds showing the good solubility in ethylene glycol as a solvent and simultaneously developed a complete halogen removal method, which is strictly prohibited in capacitors. Moreover, the incorporation of bulky α-substituents and cyclic structures dramatically improved their heat resistance and can withstand high voltage, i.e., 764 V