- Homogeneous Catalysis with Dicationic Pd(II) Complexes: Aldol Reaction of Methyl Isocyanoacetate with Benzaldehyde
-
A series of dicationic Pd(II)-acetonitrile complexes containing bi- and tridentate nitrogen and bidentate phosphine ligands (some of which are chiral) has been prepared as their BF4 salts.The molecular structures for two of these, (BF4)2
- Nesper, Reinhard,Pregosin, Paul S.,Puentener, Kurt,Woerle, Michael
-
-
Read Online
- A polycationic dendrimer as noncovalent support for anionic organometallic complexes
-
Polycationic dendrimer 1 forms a well-defined, stoichiometric assembly with eight anionic metal complexes; this assembly is successfully applied as a Lewis acidic catalyst which performs comparably to the unsupported metal complex.
- Van de Coevering, Rob,Kuil, Mark,Klein Gebbink, Robertus J. M.,Van Koten, Gerard
-
-
Read Online
- Enantioselective Synthesis: Steric and Electronic Effects of the Substrates upon Stereoselectivity in the Gold(I)-Catalyzed Aldol Reaction with Chiral Ferrocenylamine Ligands
-
Enantioselectivity in the gold(I)-catalyzed aldol reaction with chiral ferrocenylamine ligands is strongly dependent upon both the steric and electronic effects of the substrates.In the reaction of pyridine-2-, 3-, and 4-carbaldehydes with ethyl 2-isocyan
- Togni, Antonio,Pastor, Stephen D.
-
-
Read Online
- Ionic core-shell dendrimers with an octacationic core as noncovalent supports for homogeneous catalysts
-
Ionic core-shell dendrimers with an octacationic core have been applied as noncovalent supports for homogeneous catalysts. Catalytically active arylpalladium complexes, which bear a tethered sulfato group, were noncovalently attached to the ionic core-she
- Van De Coevering, Rob,Alfers, Alfred P.,Meeldijk, Johannes D.,Martinez-Viviente, Eloisa,Pregosin, Paul S.,Gebbink, Robertus J. M. Klein,Van Koten, Gerard
-
-
Read Online
- New Insights into Aldol Reactions of Methyl Isocyanoacetate Catalyzed by Heterogenized Homogeneous Catalysts
-
The Hayashi-Ito aldol reaction of methyl isocyanoacetate (MI) and benzaldehydes, a classic homogeneous Au(I)-catalyzed reaction, was studied with heterogenized homogeneous catalysts. Among dendrimer encapsulated nanoparticles (NPs) of Au, Pd, Rh, or Pt lo
- Chang, Matthew,Deraedt, Christophe V.,Faucher, Franco F.,Liu, Wen-Chi,Rodrigues De Araujo, Joyce,Somorjai, Gabor A.,Toste, F. Dean,Ye, Rong,Yuan, Bing,Zhao, Jie
-
p. 584 - 589
(2020/03/03)
-
- Highly active copper-network catalyst for the direct aldol reaction
-
The development of a highly active solid-phase catechol-copper network catalyst for direct aldol reaction is described. The catalyst was prepared from an alkyl-chain-linked bis(catechol) and a copper(II) complex. The direct aldol reaction between carbonyl
- Ohta, Hidetoshi,Uozumi, Yasuhiro,Yamada, Yoichi M. A.
-
supporting information; experimental part
p. 2545 - 2549
(2012/06/18)
-
- A new family of cinchona-derived amino phosphine precatalysts: Application to the highly enantio- and diastereoselective silver-catalyzed isocyanoacetate aldol reaction
-
A new class of readily accessible chiral amino-phosphine precatalysts derived from 9-amino(9-deoxy) epicinchona alkaloids has been developed. In combination with Ag(I) salts, these amino-phosphines performed as effective cooperative Brnsted base/Lewis aci
- Sladojevich, Filippo,Trabocchi, Andrea,Guarna, Antonio,Dixon, Darren J.
-
supporting information; experimental part
p. 1710 - 1713
(2011/04/15)
-
- Highly diastereo- and enantioselective aldol reaction of methyl α-isocyanoacetate: A cooperative catalysis approach
-
The cooperative catalyst activity between a chiral transition-metal catalyst and an achiral organocatalyst has been identified as one of the critical asymmetric reaction optimization components in the highly diastereo- and enantioselective aldol reaction
- Kim, Hun Young,Oh, Kyungsoo
-
supporting information; experimental part
p. 1306 - 1309
(2011/04/26)
-
- Catalytic performance of symmetrical and unsymmetrical sulfur-containing pincer complexes: Synthesis and tandem catalytic activity of the first PCS-pincer palladium complex
-
The synthesis and catalytic applications of a new aryl-based unsymmetrical PCS-pincer complex are reported. Preparation of the robust air- and moisture-stable PCS-pincer palladium complex 5[X] started from the symmetrical α,α′-dibromo-meta-xylene and involved the selective substitution of one bromide by PPh2(BH3), followed by substitution of the second bromide by SPh and subsequent introduction of the palladium. The new PCS complexes (5[X]) were employed as catalysts in two important organic transformations. Firstly, complex 5[Cl] displays high catalytic activity in aldol reactions but enters the catalytic cycle as a precatalyst. Secondly, complex 5- [BF4] displays tandem catalytic activity in the coupling of allyl chlorides with aldehydes and imines in the presence of hexamethylditin. In these tandem catalytic reactions the first process is the conversion of allyl chlorides into trimethylallyltin (and trimethyltin chloride) with Sn2Me6, which is followed by catalytic allylation of aldehyde and sulfonimine substrates. In addition, we present a new catalytic process for the one-pot allylation of 4-nitrobenzalde-hyde with vinyloxirane. The catalytic performance of the novel PCS-pincer palladium complex was compared to those of its symmetrical PCP- and SCS-pincer complex analogues. It was concluded that the unsymmetrical PCS complex advantageously unifies the attractive catalytic features of the corresponding symmetrical pincer complexes including both (π-) electron-withdrawing (such as phosphorus) or (σ-) electron-donating (such as sulfur and nitrogen) heteroatoms. Thus, in the aldol reaction the PCS-pincer palladium complex 5[X] provides a high turnover frequency, while in the tandem process both reactions are catalysed with sufficiently high activity.
- Gagliardo, Marcella,Selander, Nicklas,Mehendale, Nilesh C.,Van Koten, Gerard,Klein Gebbink, Robertus J. M.,Szabo, Kalman J.
-
experimental part
p. 4800 - 4809
(2009/05/27)
-
- Diastereopure cationic NCN-pincer palladium complexes with square planar η4-N,C,N,O coordination
-
Neutral NCN-pincer palladium bromide complex 2 containing the monoanionic, enantiopure pincer ligand 2,6-bis{[(S)-2-hydroxymethyl-1-pyrrolidinyl]methyl} phenyl bromide (1) with bis-ortho-(S)-prolinol substituents was synthesized and isolated as a mixture
- Gosiewska, Silvia,Martinez, Sara Herreras,Lutz, Martin,Spek, Anthony L.,Van Koten, Gerard,Gebbink, Robertus J. M. Klein
-
p. 4600 - 4607
(2007/10/03)
-
- Copper(I)-catalyzed diastereoselective formation of oxazolines and N-sulfonyl-2-imidazolines
-
A simple and short method for the reaction of methyl isocyanoacetate with aldehydes and N-sulfonylimines is presented. The reaction is catalyzed by copper(I) complexes and proceeds with excellent yields and high diastereoselectivities.
- Benito-Garagorri, David,Bocoki?, Vladica,Kirchner, Karl
-
p. 8641 - 8644
(2007/10/03)
-
- Pyrenoxy-based NCN-pincer palladium(II) molecular tweezers: Synthesis, properties in solution and catalysis
-
A highly flexible molecular tweezer, (aqua) (2,6-bis[(dimethylamino)methyl]-4-{3-[(1-pyrenyloxy)methyl]-5- (trimethylsilyl)benzyloxy}phenyl)palladium(II) tetrafluoroborate (1a), constructed from a para-hydroxy-functionalized NCN-pincer palladium(II) complex {NCN-OH = [2,6-(Me2NCH2)2 C6H2-4-OH]}, a pyrenoxy unit and a xylyl spacer, was synthesized. X-ray analysis of the structure of 1-[3-({3,5-bis[(dimethylamino)methyl]-4-(trimethylsilyl) phenyloxy}methyl)-5-bromobenzyloxy]pyrene (10), a precursor ligand of la, showed a completely flattened conformation in the solid state, imposed by favorable intramolecular π-stacking interactions. The molecular structure of la in solution proved to be fluxional on the NMR timescale. UV/Vis and (time-resolved) fluorescence spectroscopy revealed that, in spite of the high flexibility, the catalyst and pyrenoxy units are in close proximity because of cation-π interactions. This was further supported by conformer searches using molecular mechanics (MM2). The binding affinity of picric acid towards the pyrenoxy moiety was studied by 1H NMR titrations, revealing association constants Ka in the order of 101 to 102 M-1. Tweezer la shows small rate enhancements in aldol condensations of aromatic aldehydes with methyl isocyanoacetate compared to (aqua)(2,6-bis[(dimethylamino)methyl]4-{[3-(trimethylsilyl) benzyloxy}phenyl)palladium(II) tetrafluoroborate (2), which lacks the pyrenoxy unit. The tweezer was immobilized on a G2-carbosilane dendrimer, generating the dendritic (aqua)(G2-carbosilane)palladium complex 1b, showing a decreased catalytic activity compared to 1a. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Slagt, Martijn Q.,Jastrzebski, Johann T. B. H.,Klein Gebbink, Robertus J. M.,Van Ramesdonk, Hendrik J.,Verhoeven, Jan W.,Ellis, Dianne D.,Spek, Anthony L.,Van Koten, Gerard
-
p. 1692 - 1703
(2007/10/03)
-
- New mono- and tricyclopalladated dendritic systems with encapsulated catalytic sites
-
The preparation of a series of new macrocyclic carbodiazasilane molecules functionalized with the monoanionic [2,6-(CH2NMe2)2C6H3] - ≡ N,C,N-pincer ligand has been accomplished. Palladation
- Rodriguez, Gema,Lutz, Martin,Spek, Anthony L.,Van Koten, Gerard
-
-
- Fluoride-catalyzed aldol-type reactions of α-isocyano esters producing 2-oxazoline derivatives
-
An α-isocyano ester underwent the fluoride-catalyzed aldol-type reaction with an aldehyde to afford a 2-oxazoline derivative.
- Ito, Yoshihiko,Higuchi, Noriko,Murakami, Masahiro
-
-
- Macromolecular-multisite catalysts obtained by grafting diaminoaryl palladium(II) complexes onto a hyperbranched-polytriallylsilane support
-
Hyperbranched carbosilane compounds such as 1 are conveniently prepared, soluble supports for diaminoaryl Pd11 catalysts. The hyperbranched catalyst shows similar activity behavior to its parent mononuclear catalyst and provides a competitive a
- Schlenk, Christian,Kleij, Arjan W.,Frey, Holger,Van Koten, Gerard
-
p. 3445 - 3447
(2007/10/03)
-
- The gold(I)-catalyzed aldol reaction utilizing chiral ferrocenylamine ligands: synthesis of N-benzyl-substituted ligands
-
The synthesis and characterization of (R)-N-aminoethyl>-N-benzyl-1-ethyl amine (9) and selected carbamate esters is described.The stereoselectivity of the gold(I)-catalyzed r
- Pastor, Stephen D.,Kesselring, Rudolf,Togni, Antonio
-
p. 415 - 420
(2007/10/02)
-
- Asymmetric synthesis catalyzed by chiral ferrocenylphosphine transition metal complexes. 10 gold(I)-catalyzed asymmetric aldol reaction of isocyanoacetate
-
Optically active ferrocenylbisphosphine ligands containing 2-(dialkylamino)ethylamino group on the ferrocenylmethyl position have been prepared and used for the gold(I)-catalyzed asymmetric aldol reaction of isocyanoacetate with aldehydes. Six-membered ring amines, such as morpholino or piperidino group, at the terminal of the side chain were most stereoselective to give optically active trans-4- methoxycarbonyl-5-alkyl-2-oxazolines (up to 97% ee) with high enantio- and diastereoselectivity in a quantitative yield.
- Hayashi, Tamio,Sawamura, Masaya,Ito, Yoshihiko
-
p. 1999 - 2012
(2007/10/02)
-
- 86. Chiral Cooperativity: the Effect of Distant Chiral Centers in Ferrocenylamine Ligands upon Enantioselectivity in the Gold(I)-Catalyzed Aldol Reaction
-
Long-range chiral cooperativity in enatiomerically pure ferrocenylamine ligands containing both planar and multiple centers of chirality (multiple stereogenic C-atoms) was demonstrated in the AuI-catalyzed reaction of aldehydes and isocyanoeste
- Pastor, Stephen D.,Togni, Antonio
-
p. 905 - 933
(2007/10/02)
-
- Silver(I)-catalyzed asymmetric aldol reaction of isocyanoacetate
-
High stereoselectivity (over 80% ee) was attained in silver(I)-catalyzed asymmetric aldol reaction of methyl isocyanoacetate with aldehydes in the presence of a chiral (aminoalkyl)ferrocenylphosphine-silver(I) complex by slow addition of the isocyanoaceta
- Hayashi, Tamio,Uozumi, Yasuhiro,Yamazaki, Akiko,Sawamura, Masaya,Hamashima, Hitoshi,Ito, Yoshihiko
-
p. 2799 - 2802
(2007/10/02)
-
- ASYMMETRIC ALDOL REACTION OF α-ISOCYANOACETAMIDES WITH ALDEHYDES CATALYZED BY A CHIRAL FERROCENYLPHOSPHINE-GOLD(I) COMPLEX
-
Aldol reaction of N,N-dialkyl-α-isocyanoacetamides with primary alkyl aldehydes in the presence of 0.5-1 molpercent of a chiral (aminoalkyl)ferrocenylphosphine-gold(I) catalyst proceeded with high enantio- and diastereoselectivity to give trans-5-alkyl-2-oxazoline-4-carboxamides of up to 98.6percent ee, which were converted into optically active threo-β-hydroxyamino acids.
- Ito, Yoshihiko,Sawamura, Masaya,Kobayashi,Masaaki,Hayashi, Tamio
-
p. 6321 - 6324
(2007/10/02)
-
- ASYMMETRIC ALDOL REACTION OF AN ISOCYANOACETATE WITH ALDEHYDES CATALYZED BY CHIRAL FERROCENYLPHOSPHINE-GOLD(I) COMPLEXES: DESIGN AND PREPARATION OF NEW EFFICIENT FERROCENYLPHOSPHINE LIGANDS
-
An optically active ferrocenylphosphine ligand containing 2-(morpholino)ethylamino or 2-(piperidino)ethylamino group on the ferrocene side chain was effective for the goldcatalyzed aldol reaction of methyl isocyanoacetate with aldehydes to give optically active 4-methoxycarbonyl-5-alkyl-2-oxazolines (up to 96 percent ee) with high enantio- and diastereoselectivity in a quantitative yield.
- Ito, Yoshihiko,Sawamura, Masaya,Hayashi, Tamio
-
p. 6215 - 6218
(2007/10/02)
-