14990-09-1Relevant articles and documents
New N-pyrazole, P-phosphine hybrid ligands and their reactivity towards Pd(II): X-ray crystal structures of complexes with [PdCl2(N,P)] core
Guerrero, Miguel,Mu?oz, Sergio,Ros, Josep,Calvet, Teresa,Font-Bardía, Mercè,Pons, Josefina
, p. 257 - 264 (2015)
Two new N-pyrazole, P-phosphine hybrids ligands: 1-[2-(diphenylphosphanyl)methyl]-3,5-dimethylpyrazole (LP1) and 1-[2-(diphenylphosphanyl)propyl]-3,5-dimethylpyrazole (LP3) are presented. The reaction of these two ligands and two other ligands reported in
Insightful understanding of the correlations of the microstructure and catalytic performances of Pd@chitosan membrane catalysts studied by positron annihilation spectroscopy
Liu, Qi,Xu, Mengdie,Zhao, Jing,Wang, Yudong,Qi, Chenze,Zeng, Minfeng,Xia, Rui,Cao, Xingzhong,Wang, Baoyi
, p. 3225 - 3236 (2018)
In this study, the catalytic performances of palladium supported on chitosan (Pd@CS) membrane heterogeneous catalysts have been studied from the aspects of free volume by positron annihilation lifetime spectroscopy (PALS). The results showed that the variation in free volume hole size of the Pd@CS membrane catalyst was closely associated with microstructure evolutions, such as increase of Pd content, valence transition of Pd by reduction treatment, solvent swelling, physical aging during catalyst recycling, and so on. The PALS results showed that both the mean free volume hole size of the Pd0@CS membrane in the dry or swollen state (analyzed by the LT program) and its distribution (analyzed by the MELT program) are smaller than the molecule size of the reactants and products in the catalysis reaction. However, the results showed that the Pd0@CS membrane catalyst has excellent catalytic activity for the Heck coupling reaction of all the reactants with different molecule size. It was revealed that the molecule transport channels of the Pd0@CS membrane catalyst in the reaction at high temperature was through a number of instantaneously connected free volume holes rather than a single free volume hole. This hypothesis was powerfully supported by the catalytic activity assessment results of the CS layer sealed Pd0@CS membrane catalyst. Meanwhile, it was confirmed that the leaching of Pd0 nanoparticles of the reused Pd0@CS membrane catalyst during the recycling process was also through such instantaneously connected free volume holes.
Diastereoselective Synthesis of Highly Substituted, Amino- and Pyrrolidino-Tetrahydrofurans as Lead-Like Molecular Scaffolds
Wales, Steven M.,Merisor, Elena G.,Adcock, Holly V.,Pearce, Christopher A.,Strutt, Ian R.,Lewis, William,Hamza, Daniel,Moody, Christopher J.
, p. 8233 - 8239 (2018)
A series of highly substituted tetrahydrofurans (THFs), decorated with modifiable 2-aryl, 3-carboxy and 4-amino substituents, has been prepared for biological evaluation within the European Lead Factory. Diastereoselective reductive amination of pre-functionalised 4-oxofurans, readily prepared from cinnamate esters via oxa-Michael/Dieckmann annulation, provided the requisite THF cores on gram scale with three contiguous stereocentres, including full substitution at C-3. In a second series, a pyrrolidine ring was fused to the same oxofuran scaffold via an intramolecular reductive amination, inverting the configuration at C-4 relative to the other ring substituents. The resulting compounds, which displayed desirable physical properties as lead-like scaffolds, were derivatised into a small library of 24 compounds, demonstrating their ability to serve as starting points for drug discovery. Ultimately, this chemistry enabled the preparation of 1948 THF-containing compounds for inclusion in the Joint European Compound Library.
Development of the traceless phenylhydrazide linker for solid-phase synthesis
Stieber, Frank,Grether, Uwe,Waldmann, Herbert
, p. 3270 - 3281 (2003)
The hydrazide group is a new oxidatively cleavable traceless linker for solid-phase chemistry. It can be readily introduced by hydrazide formation between a carboxy-functionalized resin and different substituted hydrazines. In order to achieve high yields in this step, new carboxylic acid resins were developed that are not prone to undesired imide formation upon activation of the carboxylic acid. The polymer-bound acyl hydrazides were successfully employed in various transformations, namely Heck, Suzuki, Sonogashira, and Stille couplings, as well as Wittig and Grignard reactions. Traceless release of the coupling products from the solid support is achieved selectively under mild conditions and in high purity by oxidation of the aryl hydrazides to acyl diazenes with CuII salts or N-bromosuccinimide (NBS) and subsequent nucleophilic attack of the acyl diazene intermediates. Traceless cleavage by oxidation with NBS can be carried out as a two-step process in which stable acyl diazenes are first generated by treatment with NBS in the absence of a nucleophile. After removal of the reagents by simple resin washing, the traceless release is effected by the addition of methanol, which leads to products of high purity without any additional separation steps.
Palladium supported on polyether-functionalized mesoporous silica. Synthesis and application as catalyst for Heck coupling reaction
Grandsirea, Anne Flore,Labordeb, Coralie,Lamaty, Frederic,Mehdia, Ahmad
, p. 179 - 183 (2010)
A new catalytic system based on Pd supported on polyether-functionalized mesoporous silica was prepared. This material was obtained by co-hydrolysis and polycondensation of tetraethylorthosilicate and a bis-silylated triblock copolymer P123 (Mw = 5800) followed by the decomposition of Pd(OAc)2 salt. We have shown that this material can be applied as powerful heterogeneous catalyst for the Heck coupling reaction. Copyright
Comparing α-carbanion-stabilizing ability of substituents using the Brook rearrangement
Takeda, Kei,Ubayama, Haruka,Sano, Ayako,Yoshii, Eiichi,Koizumi, Toru
, p. 5243 - 5246 (1998)
The α-carbanion-stabilizing ability of the phenylthio and trimethylsilyl groups was compared based on the relative rate of the base- catalyzed Brook rearrangement of the β-substituted α-silylallylalcohol.
Solvent-controlled selective synthesis of a trans-configured benzimidazoline-2-ylidene palladium(II) complex and investigations of its Heck-type catalytic activity
Huynh, Han Vinh,Ho, Joanne Hui Hui,Neo, Tiong Cheng,Koh, Lip Lin
, p. 3854 - 3860 (2005)
Reaction of N,N′-dimethylbenzimidazolyl iodide (A) with Pd(OAc) 2 in DMSO gives selectively trans-bis(N,N′- dimethylbenzimidazoline-2-ylidene) palladium(II) diiodide (trans-2) in 77% yield. The selective formation of the trans-coordination isom
Tackling calibration problems of spectroscopic analysis in high-throughput experimentation
Cruz, Susana C.,Rothenberg, Gadi,Westerhuis, Johan A.,Smilde, Age K.
, p. 2227 - 2234 (2005)
High-throughput experimentation and screening methods are changing work flows and creating new possibilities in biochemistry, organometallic chemistry, and catalysis. However, many high-throughput systems rely on off-line chromatography methods that shift
Microwave-assisted copper-catalyzed heck reaction in PEG solvent
Declerck, Valérie,Martinez, Jean,Lamaty, Frédéric
, p. 3029 - 3032 (2006)
A catalytic system made of a copper salt, potassium carbonate and PEG 3400 was developed to perform a Heck arylation under microwave activation. Copper iodide gave the best results in a short reaction time (30 min) and various substituted tert-butyl cinna
Effect of N1-substituted pyrazolic hybrid ligands on palladium catalysts for the Heck reaction
Guerrero, Miguel,Pons, Josefina,Ros, Josep
, p. 1957 - 1960 (2010)
In this paper we have explored the influence of several linkers present on the [PdCl2(L)] complexes, where L is 3,5-dimethylpyrazolic hybrid ligand N1-substituted by polyether chains and/or phenyl groups. These complexes have been used as pre-c
