14221-01-3Relevant articles and documents
Hydrazine-Free Facile Synthesis of Palladium-Tetrakis(Triphenylphosphine)
Carrasco, Sergio,Martín-Matute, Belén
, p. 1951 - 1955 (2019)
We present an easy and very efficient procedure for the synthesis of Pd(PPh3)4 using nontoxic reducing agents. The complex is obtained in a remarkable 83 % yield, and the method can be scaled up. A very detailed spectroscopic and spectrometric characterization is reported.
MECHANISM OF ACETYLENE AND OLEFIN INSERTION INTO PALLADIUM-CARBON sigma BONDS.
Samsel,Norton
, p. 5505 - 5512 (1984)
The intramolecular acetylene insertion reactions of C1L//2PdCO//2(CH//2)//nC EQUVLNT CCH//3 (1a, L equals Ph//3P, n equals 2; 1b, L equals p-tol//3P, n equals 2; 2, L equals Ph//3P, n equals 3) and the intramolecular olefin insertion reaction of C1L//2PdCO//2CH//2CH//2CH equals CH//2 (3, L equals Ph//3P) have been investigated. The acetylene insertion reactions give stable vinyl complexes 5a, 5b, and 6; the olefin insertion reaction gives an unsaturated lactone by beta -hydrogen elimination from the initially formed insertion product. Kinetic and **3**1P NMR studies show that, as predicted by Thorn and Hoffmann, the reactions proceed by a four-coordinate mechanism, with the triple or double bond displacing a phosphine ligand in a rapidly maintained equilibrium prior to insertion. The triple bond in 2, with the longer carbon chain, is more easily coordinated than that in 1a but inserts less rapidly after coordination.
Synthesis and nicotinic acetylcholine-binding properties of epibatidine homologues: Homoepibatidine and dihomoepibatidine
Malpass,Hemmings,Wallis,Fletcher,Patel
, p. 1044 - 1050 (2001)
Homoepibatidine 2 and dihomoepibatidine 3 have been synthesised from the 8-azabicyclo[3.2.1]oct-6-ene 8 and the 9-azabicyclo[4.2.1]oct-7-ene 9, respectively, the key precursors for reductive Heck coupling reactions. Alternative routes starting from cyclohepta- and cycloocta-1,3-diene are described; deoxygenation of tropane and homotropane epoxides provides a convenient route to 8 and 9. The enantiomers of 2 show similar potency at nicotinic receptors to the corresponding epibatidine enantiomers; the affinity of 3 is lower.
Fluoride-catalyzed reduction of palladium(II) to palladium(0)-phosphine complexes
McLaughlin, Patrick A.,Verkade, John G.
, p. 5937 - 5940 (1998)
We demonstrate that in the presence of water and excess PPh3, fluoride ion catalyzes the reduction of (Ph3P)2PdCl 2 under mild conditions to Pd(PPh3)4 in good yields. The inactivation of catalytic F- by formation of highly stable HF2-, and other polyhydrogen fluorides that can form in the reaction, is prevented by adding a strong nonionic base such as P(MeNCH2CH2)3N.
Evidence of the formation of zerovalent palladium from Pd(OAc)2 and triphenylphosphine
Amatore, Christian,Jutand, Anny,M'Barki, Mohamed Amine
, p. 3009 - 3013 (1992)
The mixture Pd(OAc)2 + nPPh3 (n ≥ 2) and the complex Pd(OAc)2(PPh3)2 commonly used as catalysts in reactions involving aryl and vinyl halides, aryl inflates or allylic acetates spontaneously generate a zerovalent palladium complex that reacts with iodobenzene. Triphenylphosphine reduces the divalent palladium from the complex Pd(OAc)2(PPh3)2 by an intramolecular reaction and is oxidized to triphenylphosphine oxide. In the presence of an excess of triphenylphosphine, the zerovalent palladium complex generated in situ has the same 31P NMR and cyclic voltammetry properties as those of Pd0(PPh3)4.
Reductive elimination from metal phosphonate complexes: Circumvention of competing protonolysis reactions
Stockland Jr., Robert A.,Levine, Adam M.,Giovine, Matthew T.,Guzei, Ilia A.,Cannistra, Joseph C.
, p. 647 - 656 (2004)
The formation of MeP(O)(OPh)2 by reductive elimination from L2PdMe(P(O)(OPh)2) species has been investigated. The electronic and steric effects of the supporting ligands were investigated by studying reductive elimination reactions from a series of discrete complexes containing nitrogen- and phosphorus-based ligands. The P(O)-C(sp3) bond-forming reaction is slow when the intermediate species contains bidentate nitrogen ligands or small basic monodentate phosphines. Analogous complexes bearing large bite angle diphosphines such as dppf and Xantphos undergo reductive elimination at ambient temperature. The rate of MeP(O)(OPh)2 formation by reductive elimination from (dppf)PdMe(P(O)(OPh)2) is not affected by the identity or concentration of added ligand (excess dppf or PPh3), suggesting that the reductive elimination occurs from a four- or three-coordinate intermediate. When the rate of reductive elimination is slow, protonolysis reactions between L2PdMe(P(O)(OPh)2) intermediates and HP(O)(OPh)2 leads to the formation of bis-phosphonate complexes. The protonolysis reaction can be circumvented by the use of large bite angle phosphines such as dppf and Xantphos, which lead to rapid rates of P(O)-C(sp3) bond formation. These results demonstrate that the formation of P(O)-C(sp3) bonds by reductive elimination from L2PdRP(O)(OR)2 complexes is quite sensitive to the steric bulk of the supporting ligand and the presence of excess hydrogen phosphonate.
Synthesis, biological activity and molecular modeling of new biphenylic carboxamides as potent and selective CB2 receptor ligands
Bertini, Simone,Parkkari, Teija,Savinainen, Juha R.,Arena, Chiara,Saccomanni, Giuseppe,Saguto, Simone,Ligresti, Alessia,Allarà, Marco,Bruno, Agostino,Marinelli, Luciana,Di Marzo, Vincenzo,Novellino, Ettore,Manera, Clementina,Macchia, Marco
, p. 526 - 536 (2015)
The CB2 receptor is a therapeutic target of increasing importance for several diseases, including pain, inflammation, neurodegeneration, cancer and osteoporosis. While several compounds showing CB2-selective agonist or inverse agonist properties have been developed, only few CB2 receptor selective neutral antagonists are actually known. Such type of compounds could be useful to study more in depth the role of the CB2 receptor, because they lack the ability to counteract its g €constitutiveg € activity. Here we describe the synthesis and biological activity of a series of biphenylic carboxamides as a new class of CB2 receptor selective ligands. In binding assays, one of these compounds showed good CB2 receptor affinity and selectivity (Ki Combining double low line 11.48 nM; Selectivity Index Combining double low line 130). Furthermore, in functional assays, the same compound showed a very interesting pharmacological profile as CB2 receptor selective neutral antagonist. These results pave the way to further developments, including structural optimization, with the aim to obtain more potent CB2 receptor ligands with this peculiar feature.
Three-Coordinate Pd(0) with Rare-Earth Metalloligands: Synergetic CO Activation and Double P-C Bond Cleavage-Formation Reactions
Cui, Peng,Wu, Changjiang,Du, Jun,Luo, Gen,Huang, Zeming,Zhou, Shuangliu
, p. 9688 - 9699 (2021)
Metalation of β-diketiminato rare-earth metal complexes LnacnacLn(PhNCH2PPh2)2 (Ln = Y, Yb, Lu) with (COD)Pd(CH2SiMe3)2 afforded three-coordinate Pd(0) complexes supported by two sterically less bulky phosphines and a Pd → Ln dative interaction. The Pd(0) center is prone to ligation with isonitrile and CO; in the latter case, the insertion of a second CO with the Y-N bond was assisted via a precoordination of CO on the Pd(0) center, which led to the formation of an anionic Pd(0) carbamoyl. The reaction of the Pd-Y complex with iodobenzene showed a remarkable double P-C bond cleavage-formation pathway within the heterobimetallic Pd-Y core to afford (Ph3P)2PdI(Ph), imine PhNCH2, and a β-diketiminato yttrium diiodide. In the related reaction of LnacnacY(PhNCH2PPh2)2 with (Ph3P)2PdI(Ph), the P-C bond cleavage following with a N-C bond formation was observed. Computational studies revealed a synergetic bimetallic mechanism for these reactions.
Palladium-catalysed annulation reaction of allenyltins with β-iodo vinylic acids: Selective synthesis of α-pyrones
Rousset,Abarbri,Thibonnet,Duchene,Parrain
, p. 1987 - 1988 (2000)
Palladium-catalysed regio- and stereoselective annulation of allenyl stannanes by β-iodo vinylic acids gives the corresponding α-pyrones in high yields. This annulation most probably proceeds through a Stille reaction/cyclisation sequence.
Cyclopropanation of cyclohexenone by diazomethane catalyzed by palladium diacetate: Evidence for the formation of palladium(0) nanoparticles
Illa, Ona,Rodriguez-Garcia, Cristobal,Acosta-Silva, Carles,Favier, Isabelle,Picurelli, David,Oliva, Antonio,Gomez, Montserrat,Branchadell, Vicenc,Ortuno, Rosa M.
, p. 3306 - 3314 (2007)
The diazomethane-mediated cyclopropanation of cyclohexenone using Pd(OAc)2 and different sources of Pd(0) species as precatalysts has been studied. In the presence of an excess of diazomethane, Pd-(OAc)2 rapidly evolves to the formation of palladium nanoparticles (less than 1 min), which are active as catalysts in the cyclopropanation process. The nature of these particles has been analyzed through transmission electron microscopy showing a size distribution between 6 and 40 nm. These nanoparticles generated in situ are more active man Pd(0) complexes, preformed nanoparticles, and commercial palladium powder. Cyclic voltammetry measurements of the reaction solution after completion show the presence of Pd(0) species. This is the first time that Pd(0) nanoparticles are evidenced in a cyclopropanation reaction. Moreover, the reduction of Pd(OAc)2 to Pd(0) in the presence of diazomethane has been theoretically studied through density functional calculations. The formation of methyl and allyl acetates as organic byproducts has been predicted by the theoretical calculations, and these species, as well as oligomers derived from them, have been detected by spectrometric and spectroscopic techniques (MS, NMR, and IR).
