21797-13-7Relevant articles and documents
Enantioselective alternating copolymerization of α-olefins with carbon monoxide using a cationic palladium-chiral diphosphine complex
Yuan, Jian-Chao,Lu, Shi-Jie
, p. 2697 - 2703 (2001)
Enantioselective alternating copolymerization of carbon monoxide with propylene, 1-heptene, 1-octene, and styrene was carried out using a palladium catalyst modified by 1,4,3,6-dianhydro-2,5-dideoxy-2,5-bis(diphenylphosphino)-L-iditol (DDPPI). The chiral diphosphine was proved to be effective for enantioselective copolymerization. The pure poly(1,4-ketone)s were obtained by dissolving the copolymers containing spiroketal and 1,4-ketone units in 1,1,1,3,3,3-hexafluoro-2-propanol and reprecipitating with methanol. Optical rotation, elemental analysis, and 1H NMR, 13C NMR, and IR spectra showed that our copolymers were optically active, isotactic, alternating poly(1,4-ketone) structures. An oxidant and a weakly or noncoordinating anion were important in the copolymerization.
Oligomers and soluble polymers from the vinyl polymerization of norbornene and 5-vinyl-2-norbornene with cationic palladium catalysts
Blank, Frederik,Scherer, Harald,Janiak, Christoph
, p. 1 - 9 (2010)
Oligomeric vinyl polynorbornene (2 to ～12 monomer units) was obtained via hydrooligomerization of norbornene (NB) using the cationic palladium complexes [Pd(PPh3)n(NCCH3)4-n] (BF4)2 [n = 0 (1), 3 (2)] at different hydrogen pressures. The vinyl polymerization of norbornene (NB) in the ionic liquid N-butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide (BtMA +NTf2-) with [Pd(NCCH3) 4](BF4)2 led to soluble polynorbornenes (with several hundred monomer units) at different temperatures and molar NB:Pd ratios. The norbornene derivative 5-vinyl-2-norbornene (VNB) was oligomerized in high yield with 1 in CH3NO2 primarily through the (endocyclic) norbornene double bond but also through both the norbornene and (exocyclic) vinyl double bond for about every second monomer (by 1H NMR). A 2D 1H,13C-HSQC NMR analysis suggests a β-hydrogen elimination after insertion of a norbornene double bond as chain-termination mechanism. The conversion of NB or VNB increased with temperature and a lower NB:Pd and VNB:Pd ratio, respectively. The vinyl double bond in VNB slowed down the insertion rate drastically when compared with NB (activity decrease by a factor of 102).
Well-defined bisMETAMORPhos PdI-PdI complex: Synthesis, structural characterization, and reactivity
Oldenhof, Sander,De Bruin, Bas,Van Der Vlugt, Jarl Ivar,Reek, Joost N. H.,Lutz, Martin
, p. 7293 - 7298 (2014)
The formation of a bisMETAMORPhos PN-bridged dimeric PdI complex (3) from ligand 1 and Pd(dba)2 is described. The addition of 1 to Pd(dba)2 initially leads to the formation of Pd0 complex 2, which has a highly distorted tetrahedral environment and binds two neutral ligands 1. Complex 2 converts to {PdI}2 complex 3 upon heating. Complex 3 consists of a completely flat Pd-Pd core, with a Pd-Pd bond length of 2.6199(4) ?, and the Pd centers display a highly distorted square planar coordination environment. The formation of complex 3 from 2 is suggested to proceed via an in situ comproportionation pathway. Initial decoordination of one ligand from 2 followed by oxidative addition of one neutral coordinated ligand arm leads to a 1-PdIIH complex. Insertion of free dba into the Pd-H bond generates a 1-PdIIdba complex that releases 1,5-diphenylpent-1-en-3-one via intra- or intermolecular protonolysis. Concomitantly, comproportionation with 1-Pd0 yields 3. Complex 3 was found to function as a precatalyst in the Suzuki-Miyaura cross-coupling of p-chloroacetophenone with good conversions.
Cage Effect on Oxidation of Dimethyl Sulfoxide via Pd2L4 Prolate Spheroids
Hwang, Seo Young,Kim, Dongwon,Lee, Haeri,Jung, Ok-Sang
, p. 513 - 517 (2020)
Self-assembly of PdX2 (X? = NO3 ?, BF4 ?, and CF3SO3 ?) with 2,6-bis(4′-nicotinamidephenoxy)naphthalene (L) forms a series of [Pd2L4]X4 prolate spheroids. The O donors of two Me2SO molecules within the prolate spheroid cage are oriented toward the Pd(II) metal centers. In the presence of H2O2, the nestled Me2SO within the cage is efficiently oxidized to Me2SO2 at room temperature.
Hetero-multimetallic tetrakis(SCS-pincer palladium)-(metallo)porphyrin hybrids. Tunable precatalysts in a Heck reaction
Suijkerbuijk, Bart M. J. M.,Martinez, Sara D. Herreras,Van Koten, Gerard,Klein Gebbink, Robertus J. M.
, p. 534 - 542 (2008)
A series of meso-tetrakis(SCS-pincer PdCl)-(metallo)porphyrin hybrids have been synthesized using two distinct synthetic routes. Manganese and nickel were introduced into the porphyrin macrocycle prior to peripheral electrophilic palladation, whereas magnesium was introduced thereafter in light of its acid sensitivity. When these complexes were used as precatalysts in the Heck reaction between iodobenzene and styrene, different catalytic activities were observed for each hybrid complex. The catalytic activity increased for the metalloporphyrin series MnCl 2H Ni Mg, which interestingly coincides with an increase of electron richness of the porphyrin ring. Control experiments on model compounds confirmed that an intramolecular effect rather than an intermolecular effect was responsible for this influence. We postulate that, in analogy with related NCN-pincer metal complexes, the electron density on the palladium atom in SCS-pincer palladium complexes is influenced by the electronic properties of the para-substituent, i.e., the metalloporphyrin in this case. This in turn influences the rate of palladium leaching and, hence, of catalysis.
Molecular balloon, Pd6L8 cages: Recognition of alkyl sulfate surfactants
Jung, Ok-Sang,Kim, Dongwon,Lee, Haeri,Oh, Hyejin
supporting information, p. 2841 - 2844 (2020/03/17)
The unique molecular balloon system of [Pd6L8](NO3)12 (an inner cavity of 19 × 21 × 25 ?3 ← 13 × 13 × 13 ?3) was carried out via the anion exchange of nitrate with alkyl sulfates.
C2-selective direct alkynylation of indoles
Tolnai, Gergely L.,Ganss, Stephanie,Brand, Jonathan P.,Waser, Jerome
supporting information, p. 112 - 115 (2013/03/28)
The first C2-selective alkynylation of indoles using the hypervalent iodine reagent triisopropylsilylethynyl-1,2-benziodoxol-3(1H)-one (TIPS-EBX) with Pd(II) as a catalyst is described. This convenient and robust method gives a single-step access to substituted alkynyl indoles with very high C2 selectivity. The reaction is orthogonal to classical Pd(0) cross-coupling reactions, as it is tolerant to bromide and iodide substituents. The used silyl protecting group can be easily removed to give terminal acetylenes.
Terminal olefins to linear α,β-unsaturated ketones: Pd(II)/hypervalent iodine co-catalyzed wacker oxidation-dehydrogenation
Bigi, Marinus A.,White, M. Christina
supporting information, p. 7831 - 7834 (2013/07/19)
Development of a mild (35 C, no Bronsted acids) tandem Wacker oxidation-dehydrogenation of terminal olefins was accomplished using palladium(II) and hypervalent iodine co-catalysis. The reaction affords linear aryl and alkyl α,β-unsaturated ketones directly from readily available terminal olefins in good yields (average 75% per step) with excellent functional group tolerance and chemo- and stereoselectivities. The hypervalent iodine co-catalyst was found to be critical for dehydrogenation but was not effective as a stoichiometric oxidant.
Electrochemical generation of cationic Pd catalysts and application to Pd/TEMPO double-mediatory electrooxidative Wacker-type reactions
Mitsudo, Koichi,Kaide, Takashi,Nakamoto, Eriko,Yoshida, Kenta,Tanaka, Hideo
, p. 2246 - 2247 (2007/10/03)
We have developed an electrooxidative method for generating cationic palladium complexes [Pd(CH3CN)4][X]2 (X = BF4, PF6, and ClO4) from Pd(OAc)2 and several electrolytes bearing X groups in CH3CN. The system could be integrated into an electrochemical Wacker-type reaction. In the presence of a catalytic amount of TEMPO, the reaction proceeded smoothly to give the corresponding methyl ketones. Copyright
Acetonitrile and propionitrile exchange at palladium(II) and platinum(II)
Wendt, Ola F.,Kaiser, Nils-Fredrik K.,Elding, Lars I.
, p. 4733 - 4737 (2007/10/03)
Ligand exchange at square-planar [Pd(MeCN)4]2+ and [Pd(EtCN)4]2+ has been studied by 1H NMR line broadening and at [Pt(MeCN)4]2+ and [Pt(EtCN)4]2+ by isotopic labelling using 1H NMR spectroscopy in deuteriated nitromethane. Exchange takes place via two-term rate laws Rex/4 = (k1 + k2[RCN])cM with well defined k1 paths. Rate constants per co-ordination site k1298/s-1, k2298/kg mol-1 s-1 are 6.9 ± 1.6, 34 ± 3; 0.59 ± 0.12, 34 ± 3; 10.7 ± 1.8, 35 ± 4; (5.1 ± 2.3) × 10-6, (2.8 ± 0.2) × 10-5 and (5.5 ± 1.0) × 10-6, (3.3 ± 0.2) × 10-5 for [Pd(MeCN)4][CF3SO3]2, [Pd(MeCN)4][BF4]2, [Pd(EtCN)4][CF3SO3]2, [Pt(MeCN)4][CF3SO3]2 and [Pt(EtCN)4]-[CF3SO3]2, respectively. For [Pd(MeCN)4]2+ the k1 path is much larger for triflate than for tetrafluoroborate as counter ion. Changing the tetrafluoroborate concentration has no effect on the exchange rate of acetonitrile at [Pd(MeCN)4]2+. In this case the k1 path is ascribed to an attack by solvent at the metal centre. For triflate saturation kinetics is observed. This can be rationalized in terms of ion-pair formation followed by reversible intramolecular exchange of nitrile for triflate within the ion pair, with an equilibrium constant Kip300 = 8 ± 2 kg mol-1 and a rate constant k300 = 12.5 ± 1.3 s-1. All activation entropies are negative, indicating associative activation. A new, simple one-step synthesis of the substrate complexes as their triflate salts, using [M(acac)2] (acac = acetylacetonate) as starting material, and of [Pd(MeCN)4][BF4]2 using palladium(II) acetate, is described.
