33309-88-5Relevant articles and documents
A kinetics study of the oxidative addition of bromobenzene to Pd(PCy 3)2 (Cy = cyclohexyl) in a nonpolar medium: The influence on rates of added PCy3 and bromide ion
Mitchell, Emily A.,Jessop, Philip G.,Baird, Michael C.
, p. 6732 - 6738 (2009)
Bromobenzene oxidatively adds to the palladium(O) compound Pd(PCy 3)2 to give cleanly the palladium(II) product trans-PdBr(Ph)(PCy3)2. Kinetics studies of this reaction under pseudo-firstorder conditions (excess
Palladium-Catalyzed Cross-Coupling of Alkenyl Carboxylates
Becica, Joseph,Heath, Oliver R. J.,Leitch, David C.,Zheng, Cameron H. M.
supporting information, p. 17277 - 17281 (2020/07/31)
Carboxylate esters have many desirable features as electrophiles for catalytic cross-coupling: they are easy to access, robust during multistep synthesis, and mass-efficient in coupling reactions. Alkenyl carboxylates, a class of readily prepared non-aromatic electrophiles, remain difficult to functionalize through cross-coupling. We demonstrate that Pd catalysis is effective for coupling electron-deficient alkenyl carboxylates with arylboronic acids in the absence of base or oxidants. Furthermore, these reactions can proceed by two distinct mechanisms for C?O bond activation. A Pd0/II catalytic cycle is viable when using a Pd0 precatalyst, with turnover-limiting C?O oxidative addition; however, an alternative pathway that involves alkene carbopalladation and β-carboxyl elimination is proposed for PdII precatalysts. This work provides a clear path toward engaging myriad oxygen-based electrophiles in Pd-catalyzed cross-coupling.
Changing the charge: Electrostatic effects in Pd-catalyzed cross-coupling
Chan, Allen L.,Estrada, Jess,Kefalidis, Christos E.,Lavallo, Vincent
, p. 3257 - 3260 (2016/10/21)
A stable dianionic 14-electron Pd(0) complex supported by monoanionic carboranyl phosphines is reported. This complex rapidly undergoes the oxidative addition of Cl-C6H5 at room temperature and is a competent catalyst for Kumada cross-coupling. The isosteric PdL2 complex, supported by neutral o-carboranyl phosphines, does not display the same reactivity. The high reactivity of the dianionic Pd(0) complex toward chloroarenes can be explained by electrostatic effects that promote both formation of monophosphine-ligated LPd0 and stabilization of the transition state during oxidative addition. This mode of stabilization is distinct from the well-known π-arene interactions of biaryl phosphines, in that it occurs both on and off cycle.
Carbon-fluorine bond activation of tetrafluoroethylene on palladium(0) and nickel(0): Heat or lewis acidic additive promoted oxidative addition
Ohashi, Masato,Shibata, Mitsutoshi,Saijo, Hiroki,Kambara, Tadashi,Ogoshi, Sensuke
, p. 3631 - 3639 (2013/07/26)
The C-F bond cleavage reaction of tetrafluoroethylene (TFE; CF 2=CF2) with an M(0) complex (M = Pd, Ni) was investigated. The treatment of an M(0) precursor with TFE in the presence of the appropriate monodentate phosphine ligand led to a clean formation of the corresponding η2-TFE adduct (η2-TFE)M(PR3) 2. In the case of the Ni(0) species, in particular, the choice of phosphine ligands is crucial for the preparation of the desired η2-TFE complex: the use of either PCy3 or P iPr3 resulted in the target adduct, while less sterically hindered phosphines such as PPh3 and PnBu3 gave the known octafluoronickelacyclopentane as a result of the oxidative cyclization of two TFE molecules. Thermolysis of both palladium and nickel η2-TFE adducts bearing PCy3 as the ligand resulted in a C-F bond activation reaction and gave the corresponding (trifluorovinyl)metal fluorides, trans-(PCy3)2M(F)(CF=CF2). The reaction of (η2-TFE)Pd(PPh3)2 with LiI as an additive allowed cleavage of the C-F bond in THF, even at room temperature, and gave trans-(PPh3)2Pd(I)(CF=CF2) with a concomitant formation of lithium fluoride. Other metal halides, such as MgBr2 and AlCl3, also promoted the C-F bond cleavage of TFE. In addition, the use of either BF3·Et2O or B(C6F5)3 exerted a similar accelerative effect on the C-F bond activation of TFE on either nickel or palladium. The molecular structures of a series of η2-TFE and trifluorovinyl complexes were unambiguously determined by means of X-ray crystallography. The resultant (trifluorovinyl)palladium or -nickel species have shown the potential to utilize a key intermediate in cross-coupling reactions with organometallic reagents to prepare a variety of trifluorovinyl compounds.
