Search results for "Ligand design"
showing 5 items of 5 documents
Palladium-Catalyzed Direct Arylation of Heteroaromatics with Activated Aryl Chlorides Using a Sterically Relieved Ferrocenyl-Diphosphane
2012
International audience; The palladium-catalyzed direct arylations at C3 or C4 positions of heteroaromatics are known to be more challenging than at C2 or C5 positions. Aryl chlorides are also challenging substrates for direct arylation of heteroaromatics. We observed that in the presence of a palladium-catalyst combining only 0.5 mol % of Pd(OAc)2 with the sterically relieved new ferrocenyl diphosphane Sylphos, the direct arylation at C3 or C4 of oxazoles, a benzofuran, an indole, and a pyrazole was found to proceed in moderate to high yields using a variety of electron deficient aryl chlorides. Turnover numbers up to 176 have been obtained with this catalyst. Assessment of the electron-don…
nBuLi-Mediated hydrophosphination: a simple route to valuable organophosphorus compounds
2010
A straightforward synthesis of homoallyl- and allylphosphanes has been developed using nBuLi-mediated hydrophosphination of conjugated dienes. In all the cases the phosphorus atom of the reacting phosphane attacked the sterically less demanding side of the diene exclusively. In addition, high regioselectivities towards 1,2- or 1,4-addition products were observed depending on the nature of the dienes. This hydrophosphination reaction was extended to a variety of substrates such as styrene derivatives, alkynes and 1,3,5-cycloheptatriene. The structures of three hydrophosphination products were confirmed by X-ray diffraction studies.
Approaching ‘kit-type’ labelling with 68Ga : the DATA chelators.
2015
The DATA chelators are a novel class of tri-anionic ligands based on 6-amino-1,4-diazepine-triacetic acid, which have been introduced recently for the chelation of (68)Ga. Compared with macrocyclic chelators based on the cyclen scaffold (i.e., DOTA, DO3A, and DO2A derivatives), DATA chelators undergo quantitative radiolabelling more rapidly and under milder conditions. In this study, a systematic evaluation of the labelling of four DATA chelators--DATA(M), DATA(P), DATA(Ph), and DATA(PPh)--with (68)Ga is presented. The results highlight the extraordinary potential of this new class of chelators for application in molecular imaging using (68)Ga positron emission tomography (PET).
The Influence of the Amide Linkage in the FeIII-Binding Properties of Catechol-Modified Rosamine Derivatives
2015
The two new fluorescent ligands RosCat1 and RosCat2 contain catechol receptors connected to rosamine platforms through an amide linkage and were synthesized by using microwave-assisted coupling reactions of carboxyl- or amine-substituted rosamines with the corresponding catechol units and subsequent deprotection. RosCat1 possesses a reverse amide, whereas RosCat2 has the usual oriented amide bond (HNCO vs. CONH, respectively). The ligands were characterized by means of NMR spectroscopy, mass-spectrometry, and DFT calculations and X-ray crystallography studies for RosCat1. The influence of the amide linkage on the photophysical properties of the fluorescent ligands was assessed in different …
A Bipyridine‐Palladium Derivative as General Pre‐Catalyst for Cross‐Coupling Reactions in Deep Eutectic Solvents
2019
A versatile and DES‐compatible bipyridine palladium complex has been developed as a general pre‐catalyst for different cross‐coupling reactions (Hiyama, Suzuki‐Miyaura, Heck‐Mizoroki and Sonogashira) in deep eutectic solvents. Hydrogen bond capacity of the ligand allows to keep the excellent level of results previously obtained in classical organic solvents. Palladium pre‐catalyst showed a high catalytic activity for many cross‐coupling reactions, demonstrating a great versatility and applicability. Also, this methodology employs sustainable solvents as a reaction medium and highlights the potential of DES as alternative solvents in organometallic catalysis. The catalyst and DES were easily…