27384-33-4Relevant academic research and scientific papers
Cooperative Lewis acidity in borane-substituted fluorophosphonium cations
M?bus, Juri,Vom Stein, Thorsten,Stephan, Douglas W.
, p. 6387 - 6390 (2016)
A series of aryl-difluorophosphoranes are converted to give fluorophosphonium salts [Ph2PF(o-C6X4BR2)]+ (X = H, F; R = Cy, Mes). The proximity of the two weakly Lewis acidic fluorophosphonium and borane moieties results in enhanced Lewis acid catalytic reactivity.
E- Z Isomerization of Phosphine-Olefin (PEWO-F4) Ligands Revealed upon PdCl2 Capture: Facts and Mechanism
Pe?as-Defrutos, Marconi N.,Vélez, Andrea,Gioria, Estefanía,Espinet, Pablo
supporting information, p. 4701 - 4707 (2019/12/24)
The PEWO phosphines R2P(o-C6H4CH-CHC(O)Ph), R2P(o-C6H2F2CH-CHC(O)Ph), and R2P(o-C6F4CH-CHC(O)Ph) and their P-monodentate complexes trans-[PdCl2(P-monodentate)2] show, in solution and (when available) in the X-ray diffraction structures, an E configuration of the double bond. In contrast, the structures of [PdCl2(P-chelate)] display E and Z configurations. The E/Z isomerization of the latter requires first decoordination of the double bond, which then allows for easy rotation about the electron-deficient double bond. Thus, the E/Z equilibria exist for the free and the P-monodentate complexes as well but are not observed because they are extremely displaced toward the E isomer. Their capture in the form of [PdCl2(P-chelate)], with equilibrium constants on the order Keq ≈ 1-3, allows the two configurations to be observed and isolated. Evaluation of their ability to couple Pf-Pf from cis-[PdPf2(THF)2] (Pf = C6F5) affords values of their ΔG?(Pf-Pf)Pd parameters confirming that higher substitution of H by F produces lower coupling barriers and a double bond that is more electron deficient when it is free and more electron withdrawing when it is coordinated.
Phosphines with tethered electron-withdrawing olefins as ligands for efficient Pd-catalyzed aryl-alkyl coupling
Gioria, Estefania,Martinez-Ilarduya, Jesus M.,Garcia-Cuadrado, Domingo,Miguel, Jesus A.,Genov, Miroslav,Espinet, Pablo
, p. 4255 - 4261 (2013/09/02)
A group of phosphine/alkene ligands L = Ph2P(2-RC 6F4) (R = CH=CHMe, CH=CHPh, CH=CHCOPh) or Ph 2P(CH2)2CF=CF2 and their [PdCl 2L] complexes have been prepared. These phosphines are easy to prepare and fairly stable toward oxidation. Their palladium complexes feature chelated L structures with the double bond coordinated as the Z isomer, except for Ph2P(CH2)2CF=CF2, where the double bond is not coordinated and the complex is a dimer with Cl bridges. The ligands have been tested for their activity in the Negishi palladium-catalyzed aryl-alkyl coupling, where there is a competition of coupling and reduction products. Only the ligands forming chelated PdII complexes rise the coupling/reduction ratio to values 42/58 or higher. Of these, it is the ligand bearing the more electron-withdrawing substituent (R = CH=CHCOPh) that is the one producing remarkably high selectivity toward coupling: 90/10 under the usual Negishi conditions, and noticeably higher (97/3) if the proportion of ZnEt 2 in the reaction is lowered. These results fit well with the hypothesis that chelating phosphines with tethered electron-acceptor olefins improve the selectivity toward coupling products mostly because they reduce the activation barrier for C-C coupling, and not because they protect the complex from β-H elimination.
Syntheses of new tetrafluoroaryl derivatives of phosphorus and sulfur
Eller, P.Gary,Meek, Devon W.
, p. 631 - 636 (2007/10/14)
A number of polydentate phosphorus and sulfur ligands, containing one or two 1,2,3,4-tetrafluorophenyl connecting groups, were readily synthesised from the lithium derivatives of diphenyl(o-bromotetrafluorophenyl)phosphine and 2,3,4,5tetrafluorothioanisol
