5 research outputs found
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