825615-37-0Relevant articles and documents
PdII complexes of tridentate PCP N-heterocyclic carbene ligands: Structural aspects and application in asymmetric hydroamination of cyano olefins
Gischig, Sebastian,Togni, Antonio
, p. 4745 - 4754 (2005)
The synthesis of the ligand precursor 1,3-bis{(R)-1-[(S)-2- (diphenylphosphanyl)ferrocenyl]ethyl}imidazolium iodide ([PCPH]I, 1) was extended to the electronically and sterically modified ligand precursors 1,3-bis{(R)-1-[(S)-2-{[3,5-bis(trifluoromethyl)phenyl]phosphanyl}ferrocenyl] ethyl}imidazolium iodide ([3,5-CF3-PCPH]I, 6), and 1,3-bis[(R)-1-{(S)-2-[bis(3,5-dimethylphenyl)phosphanyl]ferrocenyl}ethyl] imidazolium iodide ([3,5-Me-PCPH]I, 7). Palladium complexes were prepared starting from [Pd(OAc)2]3 in THF to afford [PdI(PCP)]OAc (8), [Pd(OAc)(3,5-CF3-PCP)]I (9), and [PdI(3,5-Me-PCP)]OAc (10), in excellent yields. The crystal structures of the ligand precursor [3,5-CF 3-PCPH]I (6), the complex [PdI(3,5-CF3-PCP)]PF6 (14), as well as the dicationic complex [Pd(NCCH3)(PCP)](PF 6)2 (11), were determined by X-ray diffraction. Complex 11 and its derivative [Pd(NCCH3)-(3,5-Me-PCP)](PF6) 2 (13) have been tested as catalysts in the asymmetric addition of, for example, thiomorpholine to methacrylonitrile giving selectivities up to 63 and 75 % ee, respectively, at -80°C. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
Palladium nanocatalysts in glycerol: Tuning the reactivity by effect of the stabilizer
Reina, Antonio,Serrano-Maldonado, Alejandro,Teuma, Emmanuelle,Martin, Erika,Gómez, Montserrat
, p. 22 - 27 (2017/10/24)
Palladium nanoparticles (PdNPs) prepared in neat glycerol containing TPPTS (tris(3-sulfophenyl)phosphine trisodium salt) or cinchona-based alkaloids (cinchonidine, quinidine) as capping agents, were applied as catalysts in fluoride-free Hiyama couplings and conjugate additions with the aim of evaluating the influence of the stabilizer in the catalytic reactivity. Therefore, PdNPs stabilized by phosphine favored C–C cross-couplings, whereas those containing alkaloids showed enhanced suitability for C–C homo-couplings and conjugate additions. The metal/stabilizer coordination mode, i.e. Pd–P dative bond and π-π interaction between quinoline moiety and palladium surface, is certainly key for the stabilization of different active metallic species and then promoting distinctive catalytic pathways.
Synthesis and Structural Characterization of Nickel Complexes Possessing P-Stereogenic Pincer Scaffolds and Their Application in Asymmetric Aza-Michael Reactions
Yang, Zehua,Liu, Delong,Liu, Yangang,Sugiya, Masashi,Imamoto, Tsuneo,Zhang, Wanbin
supporting information, p. 1228 - 1237 (2015/04/27)
Novel P-stereogenic pincer-Ni complexes {κP,κC,κP-3,5-Me2-2,6-(MetBuPCH2)2C6H}NiCl (3), {κP,κC,κP-3,5-Me2-2,6-(MetBuPCH2)2C6H}NiOTf (4), [{κP,κN,κP-2,6-(MetBuPCH2)2C5H3N}NiCl]Cl (7), [{κP,κN,κP-2,6-(MetBuPCH2)2C5H3N}NiCl]BF4 (8), and [{κP,κN,κP-2,6-(MetBuPCH2)2C5H3N}Ni(NCMe)](BF4)2 (9) were synthesized in 55-84% yields and characterized by 1H NMR, 13C{1H} NMR, 31P{1H} NMR, 19F{1H} NMR, and/or single-crystal X-ray diffractions. The ORTEP diagrams of complexes 3, 7, 8, and 9 show that the coordination geometries around the Ni center in all these structures are approximately square planar but have different bond lengths and angles. These complexes were shown to be active catalysts for the asymmetric aza-Michael addition of α,β-unsaturated nitriles. For most examples good to excellent yields (up to 99%) and moderate enantiomeric excesses (up to 46% ee) were obtained. Notably, the PCP complex 3 exhibited higher catalytic activity in the aza-Michael addition than the PNP complexes 7, 8, and 9. Two achiral PCP-type pincer-Ni complexes, {κP,κC,κP-3,5-Me2-2,6-(tBu2PCH2)2C6H}NiCl (11) and {κP,κC,κP-3,5-Me2-2,6-(Ph2PCH2)2C6H}NiCl (13), were also synthesized and fully characterized in order to reveal the structural differences between the chiral and achiral complexes. (Chemical Equation Presented).
Selective and nonselective aza-michael additions catalyzed by a chiral zirconium bis-diketiminate complex
El-Zoghbi, Ibrahim,Kebdani, Myriam,Whitehorne, Todd J. J.,Schaper, Frank
, p. 6986 - 6995 (2014/01/06)
Reaction of the chiral bis-diketiminate complex rac- or (R,R)-C 6H10(nacnacXyl)2ZrCl2 with AgOTf yielded the corresponding bis-triflate complex. The complex geometry changes from distorted octahedral in the dichloride complex to a pseudotetrahedral coordination involving π coordination of the diketiminate ligands. The bis-triflate complex is highly active for aza-Michael additions with turnover frequencies of 20000/h for the addition of morpholine to acrylonitrile and 1000/h for the addition of morpholine to methacrylonitrile. The enantioselectivities of the latter reaction in various solvents were low, never surpassing 19% ee. The reaction is first-order in olefin concentration and second order in amine concentration, which is explained by its participation as a base in the reaction mechanism. The presence of catalytic amounts of triethylamine slightly increases the observed rate constants and reduces the reaction order in amine to first order. Other activated alkenes such as methacrylonitrile, crotonitrile, methyl acrylate, and cyclohexenone can be employed, but no reactivity is observed toward styrene or vinyl ethers. Primary amines, secondary amines, and anilines can be employed as nucleophiles with activities correlating with their nucleophilicity, but the catalyst is unstable in the presence of alcohols.
Addition of amines and phenols to acrylonitrile derivatives catalyzed by the POCOP-type pincer complex [{κP,κC, κP-2,6-(i-Pr2PO)2C6H 3}Ni(NCMe)][OSO2CF3]
Lefvre, Xavier,Durieux, Guillaume,Lesturgez, Stéphanie,Zargarian, Davit
experimental part, p. 1 - 7 (2011/03/23)
The pincer-type complex [{κP,κC, κP-2,6-(i-Pr2PO)2C6H 3}Ni(NCMe)][OSO2CF3] (1) can serve as a precatalyst for the regioselective, anti-Markovnikov addition of nucleophiles to activated olefins. The catalyzed additions of aliphatic amines to acrylonitrile, methacrylonitrile, and crotonitrile proceed at room temperature and give quantitative yields of products resulting from the formation of C-N bonds. On the other hand, aromatic amines or alcohols are completely inert toward methacrylonitrile and crotonitrile, and much less reactive toward acrylonitrile, requiring added base, heating, and extended reaction times to give good yields. The catalytic reactivities of 1 are thought to arise from the substitutional lability of the coordinated acetonitrile that allows competitive coordination of the nitrile moiety in the olefinic substrates; this binding enhances the electrophilicity of the CC moiety, rendering them more susceptible to attack by nucleophiles. In some cases, RCN → Ni binding results in double bond isomerization/migration (allyl cyanide) or attack of nucleophiles at the nitrile moiety (cinnamonitrile and 4-cyanostyrene). Reaction of morpholine with 1 at 60 °C led to formation of the amidine derivative 2 that has been characterized by X-ray crystallography.
Hydroamination and alcoholysis of acrylonitrile promoted by the pincer complex {κP,κC,κP-2,6- (Ph2PO)2C6H3}Ni(OSO 2CF3)
Salah, Abderrahmen B.,Offenstein, Caroline,Zargarian, Davit
experimental part, p. 5352 - 5364 (2011/12/13)
This report describes the catalytic activity of the pincer-type complex {κP,κC,κP-2,6-(Ph 2PO)2C6H3}Ni(OSO2CF 3) (1) in the anti-Markovnikov addition of aliphatic and aromatic amines and alcohols to acrylonitrile, crotonitrile, and methacrylonitrile. The influence of additives on the catalytic activities was investigated, and it was found that substoichiometric quantities of water promoted the C-N bond forming reactions catalyzed by 1, especially the reactions involving aromatic amines; in comparison, NEt3 had a less dramatic impact. The opposite pattern was observed for the alcoholysis of acrylonitrile promoted by 1: water had no beneficial effect on these reactions, while NEt3 proved to be a potent promoter. Another important difference between these reactions is that hydroamination works better with more nucleophilic amines, whereas the alcoholysis reactions work well with ArOH, CF3CH2OH, and ArCH2OH but not at all with the more nucleophilic aliphatic alcohols methanol, ethanol, and 2-propanol. Both hydroamination and alcoholysis proceed much better with acrylonitrile in comparison to its Me-substituted derivatives crotonitrile and methacrylonitrile. Under optimized conditions, precatalyst 1 promotes conjugate additions to acrylonitrile with catalytic turnover numbers of up to 100 (hydroamination) or higher (alcoholysis). Spectroscopic studies have established that the main Ni-containing species in the hydroamination reactions is a cationic adduct in which the olefinic substrate is bound to the Ni center via its nitrile moiety; this binding activates the double bond toward an outer-sphere nucleophilic attack by the amine (Michael addition). The solid-state structures of the cationic nitrile adducts [{κP, κC,κP-2,6-(Ph2PO)2C 6H3}Ni(NCR)][OSO2CF3] (R = Me (2a), CH2CH2N(H)Ph (2e)), which can be regarded as model complexes for the species involved in the hydroamination catalysis, have been elucidated. Also reported are the solid-state structures of the charge-neutral compound {κP,κC,κP-2,6-(i- Pr2PO)2C6H3}Ni(OSO 2CF3) and an octahedral Ni(II) species resulting from the aerobic/hydrolytic oxidation of 1.
Asymmetric hydroamination of acrylonitrile derivatives catalyzed by Ni(II)-complexes
Fadini, Luca,Togni, Antonio
experimental part, p. 2555 - 2562 (2009/04/06)
Chiral ferrocenyl tridentate phosphine ligands were synthesized and used in asymmetric hydroamination reactions catalyzed by Ni(II)-complexes. Compounds of the type [Ni(PPP)L]2+, where L is a chloride, solvent molecule or a coordinated substrate, were isolated. The efficiency of these complexes in asymmetric catalysis was high when aliphatic or aromatic amines were reacted with electron-poor olefins, especially with acrylonitrile derivatives. This hydroamination reaction affords up to 95% enantioselectivity at -80 °C for the addition of morpholine to methacrylonitrile (69% ee at room temperature).
Asymmetric catalytic hydroamination of activated olefins in ionic liquids
Fadini, Luca,Togni, Antonio
, p. 411 - 424 (2008/02/08)
The addition of a series of both aliphatic and aromatic amines to electron-poor olefins was investigated using [Ni(Pigiphos)(THF)]2- as catalyst (with different counterions) in various ionic liquids based on imidazolium- and picolinium-salt der
Structural variation, dynamics, and catalytic application of palladium(ii) complexes of di-N-heterocyclic carbene-amine ligands
Houghton, Jennifer,Dyson, Gavin,Douthwaite, Richard E.,Whitwood, Adrian C.,Kariuki, Benson M.
, p. 3065 - 3073 (2008/02/09)
A series of palladium(ii) complexes incorporating di-NHC-amine ligands has been prepared and their structural, dynamic and catalytic behaviour investigated. The complexes [trans-(κ2-tBuCN(Bn) CtBu)PdCl2] (12) an
Ni(II) complexes containing chiral tridentate phosphines as new catalysts for the hydroamination of activated olefins
Fadini, Luca,Togni, Antonio
, p. 30 - 31 (2007/10/03)
Ni(II) complexes containing chiral tridentate ferrocenyl phosphines (Ni(PPP)) have been found to efficiently catalyse the hydroamination of activated olefins with both anilines and aliphatic amines at r.t. (TON up to 71, TOF up to ca. 3 h-1, and enantioselectivities up to 69% ee).
