30643-33-5Relevant academic research and scientific papers
Orthogonal Nanoparticle Catalysis with Organogermanes
Fricke, Christoph,Sherborne, Grant J.,Funes-Ardoiz, Ignacio,Senol, Erdem,Guven, Sinem,Schoenebeck, Franziska
supporting information, p. 17788 - 17795 (2019/11/13)
Although nanoparticles are widely used as catalysts, little is known about their potential ability to trigger privileged transformations as compared to homogeneous molecular or bulk heterogeneous catalysts. We herein demonstrate (and rationalize) that nanoparticles display orthogonal reactivity to molecular catalysts in the cross-coupling of aryl halides with aryl germanes. While the aryl germanes are unreactive in LnPd0/LnPdII catalysis and allow selective functionalization of established coupling partners in their presence, they display superior reactivity under Pd nanoparticle conditions, outcompeting established coupling partners (such as ArBPin and ArBMIDA) and allowing air-tolerant, base-free, and orthogonal access to valuable and challenging biaryl motifs. As opposed to the notoriously unstable polyfluoroaryl- and 2-pyridylboronic acids, the corresponding germanes are highly stable and readily coupled. Our mechanistic and computational studies provide unambiguous support of nanoparticle catalysis and suggest that owing to the electron richness of aryl germanes, they preferentially react by electrophilic aromatic substitution, and in turn are preferentially activated by the more electrophilic nanoparticles.
Interrogating Pd(II) Anion Metathesis Using a Bifunctional Chemical Probe: A Transmetalation Switch
Molloy, John J.,Seath, Ciaran P.,West, Matthew J.,McLaughlin, Calum,Fazakerley, Neal J.,Kennedy, Alan R.,Nelson, David J.,Watson, Allan J. B.
supporting information, p. 126 - 130 (2018/01/17)
Ligand metathesis of Pd(II) complexes is mechanistically essential for cross-coupling. We present a study of halide→OH anion metathesis of (Ar)PdII complexes using vinylBPin as a bifunctional chemical probe with Pd(II)-dependent cross-coupling pathways. We identify the variables that profoundly impact this event and allow control to be leveraged. This then allows control of cross-coupling pathways via promotion or inhibition of organoboron transmetalation, leading to either Suzuki-Miyaura or Mizoroki-Heck products. We show how this transmetalation switch can be used to synthetic gain in a cascade cross-coupling/Diels-Alder reaction, delivering borylated or non-borylated carbocycles, including steroid-like scaffolds.
Rate and mechanism of the oxidative addition of benzoic anhydride to palladium(O) complexes in DMF
Jutand, Anny,Negri, Serge,De Vries, Johannes G.
, p. 1711 - 1717 (2007/10/03)
The rate constant of the oxidative addition of the benzoic anhydride (PhCO)2O to [Pd0(PPh3)4] has been determined in DMF and compared to that of phenyl halides and phenyl triflate. The following reactivity order has been established: PhI >> (PhCO)2O > PhOTf > PhBr. The oxidative addition of (PhCO)2O proceeds by activation of one C-O bond. Two acyl-PdII complexes are formed: a neutral complex trans-[(PhCO)Pd(OCOPh)(PPh3)2] and a cationic complex trans-[(PhCO)PdS(PPh3)2]+ (S = DMF) showing that the decarbonylation process is highly endergonic. The exchange of PPh3 by the bidentate ligand dppp does not favor the decarbonylation process.
Substitution reactions of trans-[PdXPh(SbPh3)2J (X=Cl or Br) with nitrogen, phosphines and arsenic donor ligands. Crystal structures of trans-[PdClPh(PPh3)2], [PdClPh(bipy)], [PdClPh(dppm)]2, and [PdB
Mentes, Ayfer,Kemmitt, Raymond D.W.,Fawcett, John,Russeli, David R.
, p. 1141 - 1145 (2008/10/08)
Exchange reactions of trans-[PdXPh(SbPh3)2] (1) (X=Cl or Br) with ligands L in refluxing dichloromethane give the palladium phenyl complexes [PdXPhL2] (X=Cl, L=PPh3, AsPh3, L2=2,2′-bipyridi
The trans influence of F, Cl, Br and I ligands in a series of square-planar Pd(II) complexes. Relative affinities of halide anions for the metal centre in trans-[(Ph3P)2Pd(Ph)X]
Flemming, Jeffrey P.,Pilon, Mark C.,Borbulevitch, Oleg Ya.,Antipin, Mikhail Yu.,Grushin, Vladimir V.
, p. 87 - 98 (2008/10/08)
Single crystal X-ray diffraction studies of trans-[(Ph3P)2Pd(Ph)X] (X = F (1), Cl (2), Br (3), and I (4)) were carried out. The four structures split in two isostructural and isomorphous groups, namely orthorhombic for 1 and 2 (space group Pbca, Z = 8) and triclinic for 3 and 4 (space group P-1, Z=2). According to the Pd-C bond length, the trans influence of X within these pairs follows the trend Cl > F and I > Br. However, the trans influence of Cl is slightly stronger than that of Br. Both structural and 13C NMR studies revealed that electron-donating effects of (Ph3P)2PdX increase along the series X = I - for the Pd centre in [(Ph3P)2Pd(Ph)]+ were studied by 31P NMR in rigorously anhydrous CH2Cl2 solutions, and equilibrium constants and ΔG values were obtained for all possible combinations. The sequence F- > Cl- > Br- > I- is characteristic of halide preference for the Pd complexes. Dissolving 1 and PPN Cl in dry CH2Cl2 resulted in the release of 'naked' F- which fluorinated the solvent smoothly to give a mixture of CH2ClF and CH2F2 in high yield. When chloroform was used instead of CH2Cl2, dichlorocarbene was generated slowly, forming the corresponding cyclopropane in the presence of styrene. All observations were rationalized successfully in terms of the filled/filled effect and push/pull interactions.
Palladium-promoted double-carbonylation reactions. Reactions of organopalladium compounds with carbon monoxide and amines to give α-keto amides
Ozawa, Fumiyuki,Sugimoto, Takeshi,Yuasa, Yasuhiro,Santra, Manoranjan,Yamamoto, Takakazu,Yamamoto, Akio
, p. 683 - 692 (2008/10/08)
A variety of mono- and diorganopalladium complexes, trans-PdR(X)L2 (R = Me, Et, and Ph; X = Cl, Br, I, and aryloxo; L = teritary phosphine ligand) and cis-PdMe2L2, react with carbon monoxide and secondary amines under mild conditions to give α-keto amides as double-carbonylation products. A series of acylpalladium complexes, trans-Pd(COR)X(PMePh2)2 (R = Ph, X = Cl, Br, and I; R = Me, X = Cl), the presumed reaction intermediates, were prepared, and their reactions with carbon monoxide and amines were investigated. The reaction of benzoylpalladium having bromo and iodo ligands with CO and amines proceeds more smoothly in a solvent of higher polarity than in nonpolar solvents, whereas the reaction with benzoyl(chloro)palladium complex takes place more readily in nonpolar solvents. On the basis of the effect of the solvent polarity on the reactions, two types of reaction pathways have been proposed: one involves an ionic acyl(carbonyl)palladium intermediate [PhCOPd(CO)L2]+X- attacked by amine to give acyl-carbamoyl species, from which α-keto amide is reductively eliminated, while the other mechanism proceeds through a neutral acyl-carbonyl intermediate [Pd(COR)(CO)XL]. Evidence to support the former mechanism has been obtained from the experiments using trans-[Pd(COPh)(CO)(PMePh2)2]ClO4, which is prepared by the treatment of trans-Pd(COPh)Cl(PMePh2)2 with AgClO4 and CO.
