Ruthenium(II) Pyrazolyl-Pyridyl-Oxazolinyl Complex Catalysts for the Asymmetric Transfer Hydrogenation of Ketones
作者:Wenjing Ye、Miao Zhao、Zhengkun Yu
DOI:10.1002/chem.201201703
日期:2012.8.27
Lowering the ketone: RuII complexes containing a chiral pyridyl‐based 1H‐pyrazolyl–oxazolinyl NNN ligand were synthesized and structurally characterized by X‐ray crystallographic studies. These complexcatalystsefficiently catalyzed the asymmetrictransferhydrogenation of ketones, reaching up to 99 % ee for the desired products (see scheme).
A convenient preparative method for anionic tris(substituted pyrazolyl)methane ligands
作者:Loı̈c J. Charbonnière、Raymond Ziessel
DOI:10.1016/s0040-4039(03)01506-5
日期:2003.8.11
The synthesis of tris[3-(6-carboxypyridin-2-yl)pyrazol-1-yl]methane is described in a linear multi-step protocol. The pyridyl-pyrazolyl arms are first constructed before being condensed with chloroform. Careful study of the condensation reaction shows the presence of an isomeric form of the tris(pyrazolyl)methane derivative in which one of the pyrazolyl substituents is linked through the nitrogen atom at the 2 position of the pyrazol. After acid-catalysed isomerisation to the desired isomer, the intermediate compound was subjected to a carboalkoxylation reaction and a subsequent hydrolysis. These are some rare examples of reactions directly occurring on the tris(pyrazolyl)methane platforms. (C) 2003 Elsevier Ltd. All rights reserved.
Anionically Substituted 1,1′,1″-Methylidynetris[1H-pyrazole] Ligands for the Formation of Neutral Lanthanide Complexes in Water: Synthesis, Characterization, and Photophysical Properties
作者:Loïc J. Charbonnière、Raymond Ziessel
DOI:10.1002/hlca.200390284
日期:2003.10
showed the Tb complex to be highly luminescent (ϕ=15%), while, for the Eu complex, the quantum efficiency was only 2%. Excited-state-lifetime measurements in H2O and D2O evidenced the presence of ca. three H2O molecules in the first coordination sphere of the complexes. Investigation of the Gd complex allowed the determination of the ligand-centered triplet state and showed the ligand to be well suited