Les normes, comment?

La description normalisée des ressources d’enseignement et d’apprentissage requiert l’utilisation d’outils d’implantation conformes aux conventions d’un standard ou d’une norme internationale et un réseau d’entraide et d’accompagnement

1,6,7-Trigermabicyclo[4.1.0]hept-3-en-7-yl: The Isolable Bicyclic Germyl Radical

The one-electron oxidation reaction of potassium 3,4-dimethyl-1,6,7-tris(tri-tert-butylsilyl)-1,6,7-trigermabicyclo[4.1.0]hept-3-en-7-ide (2-·K+) with tris(pentafluorophenyl)borane in THF results in the formation of stable 3,4-dimethyl-1,6,7-tris(tri-tert-butylsilyl)-1,6,7-trigermabicyclo[4.1.0]hept-3-en-7-yl (3•), representing the first bicyclic germyl radical with the bicyclo[4.1.0]hept-3-ene skeleton. The germyl radical 3• was characterized by X-ray crystallographic analysis as well as ESR spectroscopy, showing that it has a near-planar Ge-radical center

1,6,7-Trigermabicyclo[4.1.0]hept-3-en-7-yl: The Isolable Bicyclic Germyl Radical

The one-electron oxidation reaction of potassium 3,4-dimethyl-1,6,7-tris(tri-tert-butylsilyl)-1,6,7-trigermabicyclo[4.1.0]hept-3-en-7-ide (2-·K+) with tris(pentafluorophenyl)borane in THF results in the formation of stable 3,4-dimethyl-1,6,7-tris(tri-tert-butylsilyl)-1,6,7-trigermabicyclo[4.1.0]hept-3-en-7-yl (3•), representing the first bicyclic germyl radical with the bicyclo[4.1.0]hept-3-ene skeleton. The germyl radical 3• was characterized by X-ray crystallographic analysis as well as ESR spectroscopy, showing that it has a near-planar Ge-radical center

Theoretical Mechanistic Investigation of the Dynamic Kinetic Resolution of N‑Protected Amino Acid Esters using Phase-Transfer Catalysts

A detailed theoretical mechanistic investigation on the dynamic kinetic resolution of N-protected amino acid esters using phase-transfer catalysts is described. Semiautomatic exhaustive conformation search of transition state (TS)-like structures were carried out using the ConFinder program and the pseudo-TS conformational search (PTSCS) method. This conformational search method successfully provided reasonable TS structures for determining the stereoselectivity in the asymmetric base hydrolysis of hexafluoroisopropyl (HFIP) esters as well as the racemization mechanism. Furthermore, the independent gradient model (IGM) analysis of the TS structures suggested that the H-bonding interactions with the oxyanion hole and π-stacking interactions are the common important features of the proposed TS structures that determine the stereoselectivity

Comparison of fixation variability and average gaze deviations from fixation target among the DEF, N-DEF, and BF conditions.

Comparison of fixation variability and average gaze deviations from fixation target among the DEF, N-DEF, and BF conditions.</p

Theoretical Mechanistic Investigation of the Dynamic Kinetic Resolution of N‑Protected Amino Acid Esters using Phase-Transfer Catalysts

A detailed theoretical mechanistic investigation on the dynamic kinetic resolution of N-protected amino acid esters using phase-transfer catalysts is described. Semiautomatic exhaustive conformation search of transition state (TS)-like structures were carried out using the ConFinder program and the pseudo-TS conformational search (PTSCS) method. This conformational search method successfully provided reasonable TS structures for determining the stereoselectivity in the asymmetric base hydrolysis of hexafluoroisopropyl (HFIP) esters as well as the racemization mechanism. Furthermore, the independent gradient model (IGM) analysis of the TS structures suggested that the H-bonding interactions with the oxyanion hole and π-stacking interactions are the common important features of the proposed TS structures that determine the stereoselectivity

Typical examples of fixation variability.

Smooth scatter plots show typical examples of fixation variability during foveal threshold (upper) and visual field (lower) measurement in dominant eye fixation (DEF), non-dominant eye fixation (N-DEF), and binocular fixation (BF) conditions. Fixation variability of the visual field within 30° (upper) and 10° (magnified; lower) in visual field measurement. BCEA, bivariate contour ellipse area.</p

Participant demographic and ocular characteristics.

Participant demographic and ocular characteristics.</p

Comparison of standard automated perimetry findings among the DEF, N-DEF, and BF conditions.

Comparison of standard automated perimetry findings among the DEF, N-DEF, and BF conditions.</p

Dynamic Kinetic Resolution of N‑Protected Amino Acid Esters via Phase-Transfer Catalytic Base Hydrolysis

Asymmetric base hydrolysis of α-chiral esters with synthetic small-molecule catalysts is described. Quaternary ammonium salts derived from quinine were used as chiral phase-transfer catalysts to promote the base hydrolysis of N-protected amino acid hexafluoroisopropyl esters in a CHCl₃/NaOH (aq) via dynamic kinetic resolution, providing the corresponding products in moderate to good yields (up to 99%) with up to 96:4 er. Experimental and computational mechanistic studies using DFT calculation and pseudotransition state (pseudo-TS) conformational search afforded a TS model accounting for the origin of the stereoselectivity. The model suggested π-stacking and H-bonding interactions play essential roles in stabilizing the TS structures