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Alkylation of benzene with ethylene on nickel-containing amorphous and crystalline aluminosilicates
1. The zeolite-containing catalysts ABFZ-3 and ABFZ-6 have a high activity in the alkylation of benzene with ethylene. 2. Amorphous and crystalline aluminosilicates that contain Ni (as Ni2+ and NiO) are polyfunctional catalysts for the alkylation of benzene with ethylene, and can direct the reaction toward the formation of predominantly sec-butylbenzene and ethylbenzene, or sec-butylbenzene and butenes.
Minachev,Isakov,Kalinin,Lapidus,Eidus
p. 1255 - 1259
(1974)
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Chiral organolanthanides designed for asymmetric catalysis. A kinetic and mechanistic study of enantioselective olefin hydroamination/cyclization and hydrogenation by C1-Symmetric Me2Si(Me4C5)(C5H 3R*)Ln complexes where R* = chiral auxiliary
The C1-symmetric organolanthanide complexes Me2SiCp″(R*Cp)LnE(SiMe3)2 (Cp″ = η5-Me4C5; R* = (1S,2S,5R)-trans-5-methyl-cis-2-(2-propyl)cyclohexyl ((+)-neomenthyl), (1R,2S,5R)-cis-5-methyl-trans-2-(2-propyl)-cyclohexyl ((-)-menthyl), and (1R,2S,5R)-cis-5-methyl-trans-2-(2-phenyl-2-propyl)-cyclohexyl((-)- phenylmenthyl); Ln = La, Nd, Sm, Y, Lu; E = N, CH) serve as precatalysts for the efficient regio- and enantioselective hydroamination/ cyclization of the amino olefins 1-aminopent-4-ene, 2-amino-hex-5-ene, 2,2-dimethyl-1-aminopent-5-ene, and 2,2-dimethyl-1-aminohex-5-ene to yield the corresponding heterocycles 2-methylpyrrolidine, 2,5-dimethylpyrrolidine, 2,4,4-trimethylpyrrolidine, and 2,5,5-trimethylpiperidine, respectively. At 25 °C, enantiomeric excesses as high as 69% (74% at -30 °C) and turnover frequencies as high as 93 h-1 are observed. Catalyst epimerization is observed in the presence of primary amines; however, equilibrium homochiralities are frequently very high (in some cases >95%), and epimerization is complete in the early stages of preparative scale reactions. The (+)-neomenthyl, (-)-menthyl, and (-)-phenylmenthyl catalysts afford 2-methylpyrrolidines with the (R) catalyst configuration selecting for (R) product configuration and (S) catalyst configuration selecting for (S) product configuration. Product stereochemistry can be understood in terms of olefin insertion via a chairlike, seven-membered transition state. The (+)-neomenthyl precatalysts (Ln = Nd, Sm) effect the cyclization of 2-aminohex-5-ene to trarns-2,5-dimethylpyrrolidine in >95% diastereoselectivity at 25 °C. The corresponding hydrocarbyl complexes serve as precatalysts for the efficient asymmetric deuteration and hydrogenation of styrene and 2-phenyl-1-butene, respectively. For the organosamarium-derived catalysts, 2-phenyl-1-butene hydrogenation to yield exclusively 2-phenylbutane-1,2-d2 under D2 in a non-mass-transfer-limited reaction regime obeys the rate law v = k[olefin]0[lanthanide]1/2[H2]1, suggesting rapid, operationally irreversible olefin insertion (the step in which stereochemistry is fixed), a rapid preequilibrium involving an alkyl or alkyl/hydride dimer, and turnoverlimiting hydrogenolysis of an intermediate samarium alkyl with kH2/kD2 = 1.5-2.3 at 25 °C. Enantiomeric excesses as high as 64% (96% at -80 °C) and turnover frequencies as high as 26 000 h-1 are observed at 25 °C, PH2 = 1 atm for the hydrogenation of 2-phenyl-1-butene. The (R) catalyst configuration selects for the (R) product and the (S) catalyst configuration for the (S) product, with no major nonlinear effects evident in studies with (R) + (S) mixtures. Product stereochemistry can be understood in terms of olefin approach along the ring centroid-metal-ring centroid angle bisector. Under the same conditions, the deuteration of styrene proceeds at comparable rates and higher selectivities, 72% (S) and 43% (R) ee with the (70/30) (S)/(R) and (R)-(-)-menthyl samarium hydrocarbyls, respectively. Exclusive formation of ethylbenzene-1,2-d2 under D2 indicates that β-hydride elimination/readdition does not effectively compete with turnover-limiting deuterolysis.
Giardello, Michael A.,Conticello, Vincent P.,Brard, Laurent,Gagné, Michel R.,Marks, Tobin J.
p. 10241 - 10254
(1994)
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Kennedy et al.
p. 6386,6387,6388,6390
(1973)
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Alkyl Metal Asymmetric Reduction. 12. Optically Active Phenylalkanes from Organoaluminum Derivatives and Aliphatic Ketones
The reaction of β-branched alkylaluminum dichloride with some aliphatic ketones has been studied in various solvents at room temperature.In benzene, the organoaluminum derivative rapidly reduces the ketone with formation of the alkoxyaluminum dichloride, which slowly alkylates the benzene to the corresponding phenylalkane.When optically active (2-methylbutyl)aluminum dichloride is used, both the carbinol from hydrolysis of the alkoxy aluminum species and the phenylalkane are optically active and of opposite absolute configuration.The overall results are also interpreted on the basis of previous findings, and a mechanism that accounts f or the formation of the optically active phenylalkanes is presented.
Giacomelli, Giampaolo,Lardicci, Luciano
p. 4335 - 4337
(1982)
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Stereochemistry of Friedel-Crafts Alkylation of Benzene with Optically Active 2-Chlorobutane
The alkylation of benzene with (+)-2-chlorobutane (1) by Lewis acid catalyst gave stereospecifically (-)-2-phenylbutane (2) with inversion of configuration at low temperature for short reaction time.A lowering of the stereospecificity of the reaction was found to be partly due to the racemization of (+)-1- and (-)-2.
Suga, Sohei,Segi, Masahito,Kitano, Kiyoyuki,Masuda, Shinji,Nakajima, Tadashi
p. 3611 - 3612
(1981)
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Synthesis of iron(III) complex bearing tridentate β-Aminoketonato Ligand: Application to iron-catalyzed cross-coupling reaction of arylmagnesium bromides with alkyl halides
A tridentate β-aminoketonato iron complex was prepared by the reaction of lithium β-aminoketonato with FeCl3. This iron complex was found to be an efficient catalyst for the crosscoupling reaction between arylmagnesium bromides and alkyl halides.
Yamaguchi, Yoshitaka,Ando, Hiroaki,Nagaya, Makoto,Hinago, Hideto,Ito, Takashi,Asami, Masatoshi
p. 983 - 985
(2011)
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Price,Lund
p. 3105,3106
(1940)
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Enantioselective hydrogenations of arylalkenes mediated by [Ir(cod)(JM-phos)]+ complexes
Phosphine oxazoline ligands 1a-j were converted to the corresponding [Ir(cod)(phosphine oxazoline)]+ complexes 2a-j. X-ray diffraction analyses of complexes 2b, 2h, 2i, and 2j were performed. The tert-butyl-, 1,1-diphenylethyl-, and phenyl-oxazoline complexes (2b, 2h, and 2i, respectively) had typical square planar metal environments with chair-like metallocyclic rings. However, the 3,5-di-tert-butylphenyl oxazoline complex 2j was distorted toward a tetrahedral metal geometry. This library of complexes was tested in asymmetric hydrogenations of several arylalkenes. High enantioselectivities and conversions were observed for some substrates. A possible special role for the HPh2C-oxazoline substituent in asymmetric hydrogenations was identified and is discussed. In attempts to rationalize why high enantioselectivities were not observed for some alkenes, a series of deuterium labeling experiments were performed to probe for competing reactions that occurred prior to the hydrogenation step. Double bond migrations were inferred for several substrates, and this is a significant complication in asymmetric hydrogenations of arylalkenes that had not been discussed prior to this study. A mechanistic rationale is proposed involving competing double bond migration for some but not all substrates. Appreciation of this complication will be valuable in further studies aimed at optimization of enantioselection in asymmetric hydrogenations of unfunctionalized alkenes. Wiley-VCH Verlag GmbH, 2001.
Hou, Duen-Ren,Reibenspies, Joseph,Colacot, Thomas J.,Burgess, Kevin
p. 5391 - 5400
(2001)
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Pines et al.
p. 2850
(1950)
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Comparison of Lewis Acids as Catalyst for the Alkylation of Benzene with s-Butyl Chloride
The Friedel-Crafts alkylation of benzene with s-butyl chloride has been carried out in the presence of various Lewis acid catalysts.The relative order of catalyst activity is AlBr3, AlCl3, MoCl5, SbCl5 > TaCl5 > NbCl5 > FeCl3 > ZrCl4 > TiCl4 >> WCl6.The effect of addition of nitromethane on alkylation has been investigated.
Segi, Masahito,Nakajima, Tadashi,Suga, Sohei
p. 1465 - 1466
(1980)
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Iron-Catalyzed Cross-Coupling of Primary and Secondary Alkyl Halides with Aryl Grignard Reagents
An iron-catalyzed cross-coupling reaction of a primary or secondary alkyl halide with an aryl Grignard reagent proceeds under mild conditions to give the corresponding coupling product in quantitative yield. Copyright
Nakamura, Masaharu,Matsuo, Keiko,Ito, Shingo,Nakamura, Eiichi
p. 3686 - 3687
(2004)
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Probing the mechanisms of enantioselective hydrogenation of simple olefins with chiral rhodium catalysts in the presence of anions
The strong influence of various anions upon the hydrogenation of 2-phenyl-1-butene, catalyzed by chiral rhodium catalysts was investigated. Both sulfonates and halides exert large increases in the enantioselectivity when [Rh{(-)-bdpp}(NBD)]ClO4 (bdpp = 2,4-bis(diphenylphosphino)pentane, NBD=2,5-norbornadiene) is used as the catalyst precursor at high pressures (70 atm) of dihydrogen in nonpolar solvents. A dihydride mechanism similar to that for Wilkinson's catalyst [RhCl(PPh3)3] was shown to be operating at both high- and low-pressure conditions through a combination of catalytic studies, 31P, 1H and parahydrogen-induced polarization (PHIP) NMR experiments. With sulfonate and in neat methanol, however, a mechanistic switch takes place from a dihydride route (dihydrogen addition before olefin binding) at high pressure to an unsaturate route (olefin binding before dihydrogen addition) at low pressures (30 atm). Olefin isomerization is inhibited by halide addition, but occurs with sulfonate and in neat methanol through what is most likely a π-allyl mechanism. A detailed understanding of the effects of addition of these anions is crucial for development of new classes of catalysts capable of efficient enantioselective reduction of prochiral olefins lacking a secondary polar binding group.
Buriak, Julian M.,Klein, Jason C.,Herrington, Deborah G.,Osborn, John A.
p. 139 - 150
(2000)
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Photoinduced Decomposition of Peracetic Acid in Isopropylbenzene
Irradiation of peracetic acid in isopropylbenzene with 254 nm and over 290 nm lights gave as aromatic products mainly t-butylbenzene, 2-phenyl-2-propanol, and 2,3-dimethyl-2,3-diphenylbutane.The yield of t-butylbenzene was higher in 254 nm photolysis than that with >290 nm, while the yield of hydroxylated aromatics, i. e., 2-phenyl-2-propanol, was much higher with >290 nm than that with 254 nm.The distribution of products was little affected by the intensity of light.These results are discussed by a mechanism involving radicals of different reactivity derived from peracetic acid decomposition.
Ogata, Yoshiro,Tomizawa, Kohtaro
p. 2419 - 2420
(1980)
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Johnson
p. 2275
(1967)
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Cram et al.
p. 2832
(1962)
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Propylene carbonate as a solvent for asymmetric hydrogenations
(Figure Presented) A penny saved is a penny earned: The use of propylene carbonate as the solvent in iridium-catalyzed hydrogenations of non-functionalized olefins allows efficient catalyst recycling through the formation of two-phase mixtures with nonpolar solvents such as n-hexane. In the picture, the hydrogenated tetrahydronaphthalene derivative is extracted into the hydrocarbon phase.
Bayardon, Jerome,Holz, Jens,Schaeffner, Benjamin,Andrushko, Vasyl,Verevkin, Sergej,Preetz, Angelika,Boerner, Armin
p. 5971 - 5974
(2007)
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Asymmetric Hydrogenation of Disubstituted, Trisubstituted, and Tetrasubstituted Minimally Functionalized Olefins and Cyclic β-Enamides with Easily Accessible Ir-P,Oxazoline Catalysts
We have developed a family of Ir-P,oxazoline catalysts for asymmetric hydrogenation. These catalysts, with a simple modular architecture, have shown a high tolerance to the olefin geometry and substitution pattern, and to the presence of several neighboring polar groups. Thus, they were able to successfully hydrogenate disubstituted, trisubstituted, and tetrasubstituted minimally functionalized olefins (with enantiomeric excess values up to 99%). The excellent catalytic performance was also extended to the hydrogenation of cyclic β-enamides.
Biosca, Maria,Magre, Marc,Pàmies, Oscar,Diéguez, Montserrat
p. 10316 - 10320
(2018)
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Synthesis and Asymmetric Alkene Hydrogenation Activity of C2-Symmetric Enantioenriched Pyridine Dicarbene Iron Dialkyl Complexes
Enantioenriched N-alkyl-imidazole-substituted pyridine dicarbene iron dialkyl complexes have been synthesized and characterized by 1H NMR and zero-field 57Fe M?ssbauer spectroscopies as well as single-crystal X-ray diffraction. In benzene-d6, reversible coordination of N2 was observed establishing an equilibrium between a five-coordinate, S = 1 iron dialkyl derivative and the corresponding six-coordinate, diamagnetic dinitrogen complex. A modest enantioselectivity of 45% enantiomeric excess (ee) was observed for the catalytic asymmetric hydrogenation of 1-isopropyl-1-phenyl ethylene at 4 atm of H2 using 10 mol % of an enantioenriched iron dialkyl precatalyst, (ACNC)Fe(CH2SiMe3)2 ((ACNC) = bis(alkylimidazol-2-ylidene)pyridine). Decreasing the H2 pressure to 1 atm increased the ee to 70%. Incubation experiments established that the reaction of the iron dialkyl precatalysts with H2 initiates a background reaction leading to the generation of a less selective catalyst; suppressing this pathway is crucial for obtaining high enantioselectivity. The attempted hydrogenation of methyl-2-acetamidoacrylate identified a deactivation pathway where N-H bond activation generated an iron alkyl κ2-amidate alkyl. For productive catalytic reactions, deuterium labeling studies are consistent with a pathway for hydrogenation involving fast, reversible [2,1]-alkene insertion and a slow, enantiodetermining [1,2]-insertion. Monitoring the catalytic alkene hydrogenation reaction by NMR spectroscopy supports a homogeneous active catalyst that also undergoes C-H activation of the ACNC ligand backbone as a competing reaction.
Viereck, Peter,Rummelt, Stephan M.,Soja, Natalia A.,Pabst, Tyler P.,Chirik, Paul J.
supporting information
p. 1053 - 1061
(2021/05/07)

Indene Derived Phosphorus-Thioether Ligands for the Ir-Catalyzed Asymmetric Hydrogenation of Olefins with Diverse Substitution Patterns and Different Functional Groups
A family of phosphite/phosphinite-thioether ligands have been tested in the Ir-catalyzed asymmetric hydrogenation of a range of olefins (50 substrates in total). The presented ligands are synthesized in three steps from cheap indene and they are air-stable solids. Their modular architecture has been crucial to maximize the catalytic performance for each type of substrate. Improving most Ir-catalysts reported so far, this ligand family presents a broader substrate scope, covering different substitution patterns with different functional groups, ranging from unfunctionalized olefins, through olefins with poorly coordinative groups, to olefins with coordinative functional groups. α,β-Unsaturated acyclic and cyclic esters, ketones and amides werehydrogenated in enantioselectivities ranging from 83 to 99% ee. Enantioselectivities ranging from 91 to 98% ee were also achieved for challenging substrates such as unfunctionalized 1,1′-disubstituted olefins, functionalized tri- and 1,1′-disubstituted vinyl phosphonates, and β-cyclic enamides. The catalytic performance of the Ir-ligand assemblies was maintained when the environmentally benign 1,2-propylene carbonate was used as solvent. (Figure presented.).
Margalef, Jèssica,Biosca, Maria,de la Cruz-Sánchez, Pol,Caldentey, Xisco,Rodríguez-Escrich, Carles,Pàmies, Oscar,Pericàs, Miquel A.,Diéguez, Montserrat
supporting information
p. 4561 - 4574
(2021/04/05)

Activation of C-C Bonds via σ-Bond Metathesis: Hydroborenium-Catalyzed Hydrogenolysis of Cyclopropanes
High-valent transition metal or main group complex mediated σ-bond metathesis plays an important role in the activation of covalent H-E bonds. However, its involvement in the activation of C-C bonds has remained elusive. Here we describe direct hydroboration of the C-C bonds of cyclopropanes by a hydroborenium complex. Our mechanism study suggests this reaction operates through a σ-bond metathesis pathway. With this hydroborenium complex as a catalyst, hydrogenolysis of unfunctionalized cyclopropanes was achieved, which is unprecedented for homogeneous catalysts and provides an unconventional approach for C-C bond functionalization in the absence of metals.
Su, Bo,Li, Yawei,Li, Zhen Hua,Hou, Jun-Li,Wang, Huadong
supporting information
p. 4159 - 4163
(2020/04/10)

Photo-triggered hydrogen atom transfer from an iridium hydride complex to unactivated olefins
Many photoactive metal complexes can act as electron donors or acceptors upon photoexcitation, but hydrogen atom transfer (HAT) reactivity is rare. We discovered that a typical representative of a widely used class of iridium hydride complexes acts as an H-atom donor to unactivated olefins upon irradiation at 470 nm in the presence of tertiary alkyl amines as sacrificial electron and proton sources. The catalytic hydrogenation of simple olefins served as a test ground to establish this new photo-reactivity of iridium hydrides. Substrates that are very difficult to activate by photoinduced electron transfer were readily hydrogenated, and structure-reactivity relationships established with 12 different olefins are in line with typical HAT reactivity, reflecting the relative stabilities of radical intermediates formed by HAT. Radical clock, H/D isotope labeling, and transient absorption experiments provide further mechanistic insight and corroborate the interpretation of the overall reactivity in terms of photo-triggered hydrogen atom transfer (photo-HAT). The catalytically active species is identified as an Ir(ii) hydride with an IrII-H bond dissociation free energy around 44 kcal mol-1, which is formed after reductive 3MLCT excited-state quenching of the corresponding Ir(iii) hydride, i.e. the actual HAT step occurs on the ground-state potential energy surface. The photo-HAT reactivity presented here represents a conceptually novel approach to photocatalysis with metal complexes, which is fundamentally different from the many prior studies relying on photoinduced electron transfer. This journal is
Guo, Xingwei,Pfund, Bj?rn,Schreier, Mirjam R.,Wenger, Oliver S.
p. 8582 - 8594
(2020/09/07)

Deep compositional understanding of TBA: AlCl3 ionic liquid for its applications
Chloroaluminate ionic liquids (ILs) have been immensely used as homogeneous catalyst in Friedel-Crafts reaction. We have recently synthesized chloroaluminate ILs by reacting aluminium chloride with a hydrophobic neutral ligand i.e. tributylamine (TBA:AlCl3). The current study elaborates on the investigations of the composition of the ionic liquids at various stages of their formation. The ionic liquids were synthesized using various mole ratios of tributyl amine and aluminium chloride in range of 1:1 to 1:2.3, in presence of an aromatic solvent in a one pot reaction. Various characterization techniques like Mass spectrometry, 27Al Nuclear Magnetic Resonance, 31P Nuclear Magnetic Resonance and Fourier Transform Infrared spectroscopy were used to elucidate the formation of various moieties of the TBA:AlCl3 Ionic Liquid. This study also elaborates on the investigations of the cationic and anionic moieties and their structure-property relationship for various applications. Various Friedel-Crafts reaction of industrial importance were performed using the ionic liquid having (Al2Cl7)?moiety to assess its performance and compared with conventional processes. The synthesized products were characterised by sophisticated analytical techniques like 1H NMR, 13C NMR, FTIR, GC–MS, GC-FID, to name a few. This class of ionic liquids also have importance in various electrochemical applications like aluminium deposition and aluminium batteries.
Bhakthavatsalam, Vishnupriya,Chandra, Sudeshna,Choudhury, Rudra Prosad,Lande, Sharad V.,Pradhan, Jeevan,Sakhalkar, Mangesh
(2020/07/31)

Copper(II)-Photocatalyzed N-H Alkylation with Alkanes
We report a practical method for the alkylation of N-H bonds with alkanes using a photoinduced copper(II) peroxide catalytic system. Upon light irradiation, the peroxide serves as a hydrogen atom transfer reagent to activate stable C(sp3)-H bonds for the reaction with a broad range of nitrogen nucleophiles. The method enables the chemoselective alkylation of amides and is utilized for the late-stage functionalization of N-H bond containing pharmaceuticals with good to excellent yields. The mechanism of the reaction was preliminarily investigated by radical trapping experiments and spectroscopic methods.
Donabauer, Karsten,K?nig, Burkhard,Narobe, Rok,Yakubov, Shahboz,Zheng, Yi-Wen
p. 8582 - 8589
(2020/09/23)

Photocatalytic Hydromethylation and Hydroalkylation of Olefins Enabled by Titanium Dioxide Mediated Decarboxylation
A versatile method for the hydromethylation and hydroalkylation of alkenes at room temperature is achieved by using the photooxidative redox capacity of the valence band of anatase titanium dioxide (TiO2). Mechanistic studies support a radical-based mechanism involving the photoexcitation of TiO2 with 390 nm light in the presence of acetic acid and other carboxylic acids to generate methyl and alkyl radicals, respectively, without the need for stoichiometric base. This protocol is accepting of a broad scope of alkene and carboxylic acids, including challenging ones that produce highly reactive primary alkyl radicals and those containing functional groups that are susceptible to nucleophilic substitution such as alkyl halides. This methodology highlights the utility of using heterogeneous semiconductor photocatalysts such as TiO2 for promoting challenging organic syntheses that rely on highly reactive intermediates.
Zhu, Qilei,Nocera, Daniel G.
supporting information
p. 17913 - 17918
(2020/12/04)

Alkylation of Terminal Alkynes under Zinc Lewis Acid Catalysis and Its Mechanistic Studies
With a zinc Lewis acid catalyst and proton sponge in toluene, terminal alkynes were found to undergo the alkylation by alkyl triflates to provide unsymmetrical internal alkynes. This is the first example that a simple alkyl chain other than benzylic and norbornyl units can be introduced onto the alkynyl carbon atom under Lewis acid catalysis. Mechanistic studies revealed that the activation of the alkyne by the zinc Lewis acid and proton sponge is the trigger of the reaction to give a monoalkynylzinc species, which successively reacts with the alkyl triflate to afford the internal alkyne. A radical pathway is unlikely in this system. (Figure presented.).
Osano, Mana,Kida, Takeru,Yonekura, Kyohei,Tsuchimoto, Teruhisa
supporting information
p. 2825 - 2831
(2019/04/13)

Tandem Peterson olefination and chemoselective asymmetric hydrogenation of β-hydroxy silanes
Here, we report the first Ir-N,P complex catalyzed tandem Peterson olefination and asymmetric hydrogenation of β-hydroxy silanes. This reaction resulted in the formation of chiral alkanes in high isolated yields (up to 99%) and excellent enantioselectivity (up to 99% ee) under mild conditions. Modification of the reaction conditions provides a choice to transform either an olefin or the β-hydroxy silane in a chemoselective manner. Additionally, based on this method, an expedient enantioselective synthesis of (S)-(+)-α-curcumene, from a simple ketone, was accomplished in two steps with 75% overall yield and 95% ee.
Krajangsri, Suppachai,Wu, Haibo,Liu, Jianguo,Rabten, Wangchuk,Singh, Thishana,Andersson, Pher G.
p. 3649 - 3653
(2019/03/28)

Diastereo- and Enantioselective Synthesis of Fluorine Motifs with Two Contiguous Stereogenic Centers
The synthesis of chiral fluorine containing motifs, in particular, chiral fluorine molecules with two contiguous stereogenic centers, has attracted much interest in research due to the limited number of methods available for their preparation. Herein, we report an atom-economical and highly stereoselective synthesis of chiral fluorine molecules with two contiguous stereogenic centers via azabicyclo iridium-oxazoline-phosphine-catalyzed hydrogenation of readily available vinyl fluorides. Various aromatic, aliphatic, and heterocyclic systems with a variety of functional groups were found to be compatible with the reaction and provide the highly desirable product as single diastereomers with excellent enantioselectivities.
Ponra, Sudipta,Rabten, Wangchuk,Yang, Jianping,Wu, Haibo,Kerdphon, Sutthichat,Andersson, Pher G.
p. 13878 - 13883
(2018/10/24)

Teaching an old carbocation new tricks: Intermolecular C-H insertion reactions of vinyl cations
Vinyl carbocations have been the subject of extensive experimental and theoretical studies over the past five decades. Despite this long history in chemistry, the utility of vinyl cations in chemical synthesis has been limited, with most reactivity studies focusing on solvolysis reactions or intramolecular processes. Here we report synthetic and mechanistic studies of vinyl cations generated through silylium-weakly coordinating anion catalysis. We find that these reactive intermediates undergo mild intermolecular carbon-carbon bond-forming reactions, including carbon-hydrogen (C-H) insertion into unactivated sp3 C-H bonds and reductive Friedel-Crafts reactions with arenes. Moreover, we conducted computational studies of these alkane C-H functionalization reactions and discovered that they proceed through nonclassical, ambimodal transition structures. This reaction manifold provides a framework for the catalytic functionalization of hydrocarbons using simple ketone derivatives.
Popov, Stasik,Shao, Brian,Bagdasarian, Alex L.,Benton, Tyler R.,Zou, Luyi,Yang, Zhongyue,Houk,Nelson, Hosea M.
p. 381 - 387
(2018/08/07)

Triazolylidene Iridium Complexes for Highly Efficient and Versatile Transfer Hydrogenation of C=O, C=N, and C=C Bonds and for Acceptorless Alcohol Oxidation
A set of iridium(I) and iridium(III) complexes is reported with triazolylidene ligands that contain pendant benzoxazole, thiazole, and methyl ether groups as potentially chelating donor sites. The bonding mode of these groups was identified by NMR spectroscopy and X-ray structure analysis. The complexes were evaluated as catalyst precursors in transfer hydrogenation and in acceptorless alcohol oxidation. High-valent iridium(III) complexes were identified as the most active precursors for the oxidative alcohol dehydrogenation, while a low-valent iridium(I) complex with a methyl ether functionality was most active in reductive transfer hydrogenation. This catalyst precursor is highly versatile and efficiently hydrogenates ketones, aldehydes, imines, allylic alcohols, and most notably also unpolarized olefins, a notoriously difficult substrate for transfer hydrogenation. Turnover frequencies up to 260 h-1 were recorded for olefin hydrogenation, whereas hydrogen transfer to ketones and aldehydes reached maximum turnover frequencies greater than 2000 h-1. Mechanistic investigations using a combination of isotope labeling experiments, kinetic isotope effect measurements, and Hammett parameter correlations indicate that the turnover-limiting step is hydride transfer from the metal to the substrate in transfer hydrogenation, while in alcohol dehydrogenation, the limiting step is substrate coordination to the metal center.
Mazloomi, Zahra,Pretorius, René,Pàmies, Oscar,Albrecht, Martin,Diéguez, Montserrat
p. 11282 - 11298
(2017/09/25)

Alternatives to Phosphinooxazoline (t-BuPHOX) Ligands in the Metal-Catalyzed Hydrogenation of Minimally Functionalized Olefins and Cyclic β-Enamides
This study presents a new series of readily accessible iridium- and rhodium-phosphite/oxazoline catalytic systems that can efficiently hydrogenate, for the first time, both minimally functionalized olefins and functionalized olefins (62 examples in total) in high enantioselectivities (ees up to >99%) and conversions. The phosphite-oxazoline ligands, which are readily available in only two synthetic steps, are derived from previous privileged 4-alkyl-2-[2-(diphenylphosphino)phenyl]-2-oxazoline (PHOX) ligands by replacing the phosphine moiety by a biaryl phosphite group and/or the introduction of a methylene spacer between the oxazoline and the phenyl ring. The modular design of the ligands has given us the opportunity not only to overcome the limitations of the iridium-PHOX catalytic systems in the hydrogenation of minimally functionalized Z-olefins and 1,1-disubstituted olefins, but also to expand their use to unfunctionalized olefins containing other challenging scaffolds (e.g., exocyclic benzofused and triaryl-substituted olefins) and also to olefins with poorly coordinative groups (e.g., α,β-unsaturated lactams, lactones, alkenylboronic esters, etc.) with enantioselectivities typically >95% ee. Moreover, both enantiomers of the hydrogenation product could be obtained by simply changing the configuration of the biaryl phosphite moiety. Remarkably, the new catalytic systems also provided excellent enantioselectivities (up to 99% ee) in the asymmetric hydrogenation of another challenging class of olefins – the functionalized cyclic β-enamides. Again, both enantiomers of the reduced amides could be obtained by changing the metal from Ir to Rh. We also demonstrated that environmentally friendly propylene carbonate can be used with no loss of enantioselectivity. Another advantage of the new ligands over the PHOX ligands is that the best ligands are derived from the affordable (S)-phenylglycinol rather than from the expensive (S)-tert-leucinol. (Figure presented.).
Biosca, Maria,Magre, Marc,Coll, Mercè,Pàmies, Oscar,Diéguez, Montserrat
p. 2801 - 2814
(2017/08/23)

Amphipathic monolith-supported palladium catalysts for chemoselective hydrogenation and cross-coupling reactions
A palladium catalyst immobilized on an amphipathic and monolithic polystyrene-divinylbenzene polymer bearing strongly acidic cation exchange functions (sulfonic acid moieties) (Pd/CM) was developed. It was used as a catalyst for hydrogenation and ligand-free cross-coupling reactions, such as the Suzuki-Miyaura, Mizoroki-Heck, and copper- and amine-free Sonogashira-type reactions, together with a palladium catalyst supported on monolithic polymer (Pd/AM) bearing basic anion exchange functions (ammonium salt moieties), which has been in practical use for the decomposition of hydrogen peroxide produced as a byproduct during the manufacture of ultrapure water. While the Pd/CM was highly active as a catalyst for the hydrogenation and a variety of reducible functional groups could be reduced, the use of Pd/AM led to a unique chemoselective hydrogenation. Aromatic carbonyl groups were tolerant under the Pd/AM-catalyzed hydrogenation conditions, although benzyl esters, benzyl ethers, and N-Cbz groups could be smoothly hydrocracked. The cross-coupling reactions readily proceeded using either catalyst. The palladium leaching from the Pd/CM into the reaction media was never observed during the Sonogashira-type reaction, which was hardly achieved by other palladium-supported heterogeneous catalysts due to the good affinity of the palladium species with alkynes.
Monguchi, Yasunari,Wakayama, Fumika,Ueda, Shun,Ito, Ryo,Takada, Hitoshi,Inoue, Hiroshi,Nakamura, Akira,Sawama, Yoshinari,Sajiki, Hironao
p. 1833 - 1840
(2017/01/21)

Copper-catalyzed cross-coupling reactions of non-activated primary, secondary or tertiary alkyl chlorides with phenylmagnesium bromide
Efficient copper-catalyzed cross-coupling reactions of non-activated alkyl chlorides, including primary, secondary, and tertiary alkyl chlorides, with phenyl Grignard reagents were achieved. Preparation of phenylmagnesium bromide in 2-methyltetrahydrofuran is critical for the success of the reaction. This protocol expands the synthetic toolbox for the construction of C[sbnd]C bonds of non-activated primary, secondary, and tertiary alkyl chlorides via copper-catalyzed cross-coupling.
Tao, Chuanzhou,Sun, Lei,Wang, Bin,Liu, Zhou,Zhai, Yadong,Zhang, Xiulian,Shi, Dahua,Liu, Weiwei
supporting information
p. 305 - 308
(2017/01/03)

Copper(i)-catalysed asymmetric allylic reductions with hydrosilanes
A copper(i)-catalysed asymmetric allylic reduction enables a regio- and stereoselective transfer of a hydride nucleophile in an SN2′-fashion onto allylic bromides. This transformation represents a conceptually orthogonal approach to allylic substitution reactions with carbon nucleophiles. A copper(i) complex based upon a chiral N-heterocyclic carbene (NHC) ligand allows for stereoselectivity reaching 99% ee. The catalyst enables a stereoconvergent reaction irrespective of the double bond configuration of the starting materials.
Thanh Nguyen,Thiel, Niklas O.,Teichert, Johannes F.
supporting information
p. 11686 - 11689
(2017/11/03)

Nickel-Catalyzed Reductive Cross-Coupling of Aryl Bromides with Alkyl Bromides: Et3N as the Terminal Reductant
Reductive cross-coupling has emerged as a direct method for the construction of carbon-carbon bonds. Most cobalt-, nickel-, and palladium-catalyzed reductive cross-coupling reactions to date are limited to stoichiometric Mn(0) or Zn(0) as the reductant. One nickel-catalyzed cross-coupling paradigm using Et3N as the terminal reductant is reported. By using this photoredox catalysis and nickel catalysis approach, a direct Csp2-Csp3 reductive cross-coupling of aryl bromides with alkyl bromides is achieved under mild conditions without stoichiometric metal reductants.
Duan, Zhengli,Li, Wu,Lei, Aiwen
supporting information
p. 4012 - 4015
(2016/08/30)

Enantioselective synthesis of tunable chiral clickphine P,N-ligands and their application in Ir-catalyzed asymmetric hydrogenation
A small library of highly tunable chiral Clickphine P,N-ligands has been prepared in an enantioselective fashion by CuI-catalyzed asymmetric propargylic amination using a single chiral complex and a subsequent in situ cycloaddition click reaction. The scope of the propargylic amination to yield optically active triazolyl amines is described. The amines are transformed in a one-pot procedure to the corresponding Ir-Clickphine complexes, which serve as catalysts for the asymmetric hydrogenation of di-, tri-, and tetrasubstituted unfunctionalized alkenes. Enantioselectivities of up to 90% ee were obtained in these hydrogenations, which are among the best reported in the case of the tetrasubstituted substrate 2-(4′-methoxyphenyl)-3-methylbut-2-ene (9) (87% ee). This is a demonstration of the effective use of the chiral pool, as from one chiral catalyst a library of chiral Ir complexes has been synthesized that can hydrogenate various alkenes with high selectivity.
Wassenaar, Jeroen,Detz, Remko J.,De Boer, Sandra Y.,Lutz, Martin,Van Maarseveen, Jan H.,Hiemstra, Henk,Reek, Joost N. H.
p. 3634 - 3642
(2015/04/22)

Extending the substrate scope of bicyclic p-oxazoline/thiazole ligands for ir-catalyzed hydrogenation of unfunctionalized olefins by introducing a biaryl phosphoroamidite group
This study identifies a series of Ir-bicyclic phosphoroamidite-oxazoline/thiazole catalytic systems that can hydrogenate a wide range of minimally functionalized olefins (including E- and Z-tri- and disubstituted substrates, vinylsilanes, enol phosphinates, tri- and disubstituted alkenylboronic esters, and ?±,?2-unsaturated enones) in high enantioselectivities (ee values up to 99%) and conversions. The design of the new phosphoroamidite-oxazoline/thiazole ligands derives from a previous successful generation of bicyclic N-phosphane-oxazoline/thiazole ligands, by replacing the N-phosphane group with a p-acceptor biaryl phosphoroamidite moiety. A small but structurally important family of Ir-phosphoroamidite-oxazoline/thiazole precatalysts has thus been synthesized by changing the nature of the Ndonor group (either oxazoline or thiazole) and the configuration at the biaryl phosphoroamidite moiety. The substitution of the N-phosphane by a phosphoroamidite group in the bicyclic N-phosphane-oxazoline/thiazole ligands extended the range of olefins that can be successfully hydrogenated.
Biosca, Maria,Paptchikhine, Alexander,P??mies, Oscar,Andersson, Pher G.,Di??guez, Montserrat
supporting information
p. 3455 - 3464
(2015/03/04)

Iridium-Catalyzed Asymmetric Hydrogenation with Simple Cyclohexane-Based P/S Ligands: In Situ HP-NMR and DFT Calculations for the Characterization of Reaction Intermediates
We report a reduced but structurally valuable phosphite/phosphinite-thioether ligand library for the Ir-hydrogenation of 40 minimally functionalized alkenes, including relevant examples with poorly coordinative groups. We found that enantiomeric excesses are mainly dependent on the substrate structure and on some ligand parameters (i.e., the type of thioether/phosphorus moieties and the configuration of the phosphite group), whereas the substituents of the biaryl phosphite moiety had little impact. By tuning the ligand parameters we were able to find highly selective catalysts for a range of substrates (ees up to 99%). These phosphite/phosphinite-thioether ligands have a simple backbone and thus yield simple NMR spectra that reduce signal overlap and facilitate the identification of relevant intermediates. Therefore, by combining HP-NMR spectroscopy and theoretical studies, we were also able to identify the catalytically competent Ir-dihydride alkene species, which made it possible to explain the enantioselectivity obtained.
Borràs, Carlota,Biosca, Maria,Pàmies, Oscar,Diéguez, Montserrat
p. 5321 - 5334
(2015/11/18)

Direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides
The direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides proceeded in the absence of coordinating ethereal solvents at ambient temperature without the addition of a catalyst. The C(sp2)-C(sp3) cross-coupling showed excellent functional-group tolerance, and products were isolated in high yields, generally without the requirement for purification by chromatography. This process represents an expedient, operationally simple method for the construction of new C(sp2)-C(sp3) bonds. Zinc and you'll miss it. Direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with alkyl halides proceeded rapidly at ambient temperature without a coordinating ethereal solvent or an added catalyst (see scheme). This versatile, operationally simple approach to C(sp2)-C(sp3) bond formation enables the expedient construction of a diverse array of carbon-based structural motifs.
Dunsford, Jay J.,Clark, Ewan R.,Ingleson, Michael J.
supporting information
p. 5688 - 5692
(2015/05/19)

A Concise and Atom-Economical Suzuki-Miyaura Coupling Reaction Using Unactivated Trialkyl- and Triarylboranes with Aryl Halides
A concise and atom-economical Suzuki-Miyaura coupling of trialkyl- and triarylboranes with aryl halides is described. This new protocol represents the first general, practical method that efficiently utilizes peralkyl and peraryl groups of the unactivated trialkyl- and triarylboranes for the Suzuki-Miyaura coupling reaction.
Li, Hongmei,Zhong, Yong-Li,Chen, Cheng-Yi,Ferraro, Ashley E.,Wang, Dengjin
p. 3616 - 3619
(2015/07/28)

Iridium catalysts with Chiral bicyclic pyridine-phosphane ligands for the asymmetric hydrogenation of olefins
New bicyclic pyridine-phosphane ligands were prepared, and their iridium complexes were evaluated in asymmetric hydrogenation of trisubstituted olefins with non-coordinating and weakly coordinating substituents. The iridium catalysts showed high reactivity and enantioselectivity for both types of olefins. New pyridine-derived N,P-chelated iridium catalysts were prepared and evaluated in the asymmetric hydrogenation of trisubstituted olefins. High conversions and enantioselectivities were obtained. Copyright
Quan, Xu,Parihar, Vijay Singh,Bera, Milan,Andersson, Pher G.
p. 140 - 146
(2014/01/06)

A theoretically-guided optimization of a new family of modular P,S-ligands for iridium-catalyzed hydrogenation of minimally functionalized olefins
A library of modular iridium complexes derived from thioether-phosphite/phosphinite ligands has been evaluated in the asymmetric iridium-catalyzed hydrogenation of minimally functionalized olefins. The modular ligand design has been shown to be crucial in finding highly selective catalysts for each substrate. A DFT study of the transition state responsible for the enantiocontrol in the Ir-catalyzed hydrogenation is also described and used for further optimization of the crucial stereodefining moieties. Excellent enantioselectivities (enantiomeric excess (ee) values up to 99%) have been obtained for a range of substrates, including E- and Z-trisubstituted and disubstituted olefins, α,β-unsaturated enones, tri- and disubstituted alkenylboronic esters, and olefins with trifluoromethyl substituents.
Margalef, Jèssica,Caldentey, Xisco,Karlsson, Erik A.,Coll, Mercè,Mazuela, Javier,Pàmies, Oscar,Diéguez, Montserrat,Pericàs, Miquel A.
supporting information
p. 12201 - 12214
(2015/03/31)

Catalytic hydrogenation activity and electronic structure determination of bis(arylimidazol-2-ylidene)pyridine Cobalt Alkyl and Hydride Complexes
The bis(arylimidazol-2-ylidene)pyridine cobalt methyl complex, ( iPrCNC)CoCH3, was evaluated for the catalytic hydrogenation of alkenes. At 22 C and 4 atm of H2 pressure, ( iPrCNC)CoCH3 is an effective precatalyst for the hydrogenation of sterically hindered, unactivated alkenes such as trans-methylstilbene, 1-methyl-1-cyclohexene, and 2,3-dimethyl-2-butene, representing one of the most active cobalt hydrogenation catalysts reported to date. Preparation of the cobalt hydride complex, (iPrCNC)CoH, was accomplished by hydrogenation of (iPrCNC)CoCH3. Over the course of 3 h at 22 C, migration of the metal hydride to the 4-position of the pyridine ring yielded (4-H2-iPrCNC)CoN2. Similar alkyl migration was observed upon treatment of (iPrCNC)CoH with 1,1-diphenylethylene. This reactivity raised the question as to whether this class of chelate is redox-active, engaging in radical chemistry with the cobalt center. A combination of structural, spectroscopic, and computational studies was conducted and provided definitive evidence for bis(arylimidazol-2- ylidene)pyridine radicals in reduced cobalt chemistry. Spin density calculations established that the radicals were localized on the pyridine ring, accounting for the observed reactivity, and suggest that a wide family of pyridine-based pincers may also be redox-active.
Yu, Renyuan Pony,Darmon, Jonathan M.,Milsmann, Carsten,Margulieux, Grant W.,Stieber, S. Chantal E.,Debeer, Serena,Chirik, Paul J.
supporting information
p. 13168 - 13184
(2013/09/24)

A modular furanoside thioether-phosphite/phosphinite/ phosphine ligand library for asymmetric iridium-catalyzed hydrogenation of minimally functionalized olefins: Scope and limitations
A highly modular furanoside thioether-phosphite/phosphinite/phosphine ligand library has been synthesized for the iridium-catalyzed asymmetric hydrogenation of minimally functionalized olefins. These ligands can be prepared efficiently from easily accessible D-(+)-xylose. We found that their effectiveness at transferring the chiral information in the product can be tuned by correctly choosing the ligand components. Enantioselectivities were therefore excellent (ees up to 99%) in a wide range of E- and Z-trisubstituted alkenes using 5-deoxyribofuranoside thioether-phosphite ligands. It should be pointed out that these catalysts are also very tolerant to the presence of a neighbouring polar group. For 1,1-disubstituted substrates, both enantiomers of the hydrogenation product can be obtained in high enantioselectivities simply by changing the configuration of the biaryl phosphite moiety. The asymmetric hydrogenation was also performed using propylene carbonate as solvent, which allowed the iridium catalysts to be reused while maintaining the excellent enantioselectivities. Copyright
Coll, Mercedes,Pamies, Oscar,Dieguez, Montserrat
supporting information
p. 143 - 160
(2013/03/28)

A phosphite-pyridine/iridium complex library as highly selective catalysts for the hydrogenation of minimally functionalized olefins
A modular library of readily available phosphite-pyridine ligands has been successfully applied for the first time in the iridium-catalyzed asymmetric hydrogenation of a broad range of minimally functionalized olefins. The modular ligand design has been shown to be crucial in finding highly selective catalytic systems for each substrate. Excellent enantioselectivities (ees up to 99%) have therefore been obtained in a wide range of E- and Z-trisubstituted alkenes, including more demanding triaryl-substituted olefins and dihydronaphthalenes. This good performance extends to the very challenging class of terminal disubstituted olefins, and to olefins containing neighbouring polar groups (ees up to 99%). Both enantiomers of the reduction product can be obtained in excellent enantioselectivities by simply changing the configuration of the carbon next to the phosphite moiety. The hydrogenations were also performed using propylene carbonate as solvent, which allowed the iridium catalyst to be reused and maintained the excellent Copyright
Mazuela, Javier,Pamies, Oscar,Dieguez, Montserrat
supporting information
p. 2569 - 2583
(2013/10/21)

IRON BISPHENOLATE COMPLEXES AND METHODS OF USE AND SYNTHESIS THEREOF
The present application, relates to iron bisphenolate complexes and methods of use and synthesis thereof. The iron complexes are prepared from tridentate or tetradentate ligands of Formula I: wherein R1 and R2 are as defined herein. Also provided are methods and processes of using the iron bisphenolate complexes as catalysts in cross-coupling reactions and in controlled radical polymerizations.
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Paragraph 00187-00191

(2013/04/25)

Enantioselective Ir-catalyzed hydrogenation of minimally functionalized olefins using pyranoside phosphinite-oxazoline ligands
Pyranoside phosphinite-oxazoline ligands prepared from readily available (+)-D-glucosamine were applied to the Ir-catalyzed asymmetric hydrogenation of minimally functionalized olefins. Our results show that the enantioselectivity is dependent on the ozaxoline and the phosphinite moieties and the substrate structure. By carefully selecting the ligand components, enantioselectivities up to 99 % were obtained in the asymmetric reduction of several (E)- and (Z)-trisubstituted and 1,1-disubstituted olefins. The asymmetric hydrogenation was also performed using propylene carbonate as solvent, which allowed the iridium catalysts to be reused and maintained the high enantioselectivities. Copyright
Mazuela, Javier,Pamies, Oscar,Dieguez, Montserrat
p. 2139 - 2145
(2013/05/22)

Expanded scope of the asymmetric hydrogenation of minimally functionalized olefins catalyzed by iridium complexes with phosphite-thiazoline ligands
We have replaced the oxazoline group with a thiazoline moiety in one of the most successful of the phosphite-oxazoline ligand families for the Ir-catalyzed hydrogenation of minimally functionalized olefins. A small but structurally important library of Ir phosphite-thiazoline precatalysts (Ir-L1-L2a-e) has been developed by changing the substituents/configurations at the biaryl phosphite group. We found that the replacement of the oxazoline with a thiazoline moiety in the ligand design is beneficial in terms of substrate scope.
Mazuela, Javier,Pamies, Oscar,Dieguez, Montserrat
p. 2410 - 2417
(2013/08/23)

SIAPhos: Phosphorylated sulfonimidamides and their use in iridium-catalyzed asymmetric hydrogenations of sterically hindered cyclic enamides
Phosphorylated sulfonimidamides (SIAPhos) undergo ion exchange reactions with cationic complexes, [Rh(cod)2BF4] and [Ir(cod) 2BarF], or neutral complexes [Rh(cod)Cl] 2 and [Ir(cod)Cl] 2, leading to unprecedented neutral complexes with PN- S-N chelates. Use of the resulting neutral iridium complexes in asymmetric hydrogenation reactions of tri- and tetrasubstituted enamides leads to products with high enantioselectivities (up to 92% ee).
Patureau, Frederic W.,Worch, Christin,Siegler, Maxime A.,Spek, Anthony L.,Bolm, Carsten,Reek, Joost N. H.
supporting information; experimental part
p. 59 - 64
(2012/04/10)

Copper-catalyzed cross-coupling of nonactivated secondary alkyl halides and tosylates with secondary alkyl grignard reagents
Practical catalytic cross-coupling of secondary alkyl electrophiles with secondary alkyl nucleophiles under Cu catalysis has been realized. The use of TMEDA and LiOMe is critical for the success of the reaction. This cross-coupling reaction occurs via an SN2 mechanism with inversion of configuration and therefore provides a general approach for the stereocontrolled formation of C-C bonds between two tertiary carbons from chiral secondary alcohols.
Yang, Chu-Ting,Zhang, Zhen-Qi,Liang, Jun,Liu, Jing-Hui,Lu, Xiao-Yu,Chen, Huan-Huan,Liu, Lei
supporting information; experimental part
p. 11124 - 11127
(2012/08/28)

Microwave-assisted silica-supported aluminum chloride-catalyzed Friedel-Crafts alkylation
Microwave irradiation is a popular method in organic synthesis to achieve high yields in shorter reaction times. This decreases total 'man-hours' in a synthetic setting. Another technique used in organic chemistry to decrease manual manipulations, is solid support reagents. The benefits of this approach is that upon completion of a reaction, a simple filtration can be performed which expedites the work-up and also produces less organic waste. Friedel-Crafts alkylation has been explored using microwave chemistry as well as with solid-supported reagents. In comparison with traditional heating, as well as with AlCl3, superior yields were observed with silica-gel bound aluminum chloride (Si-AlClx) when microwave irradiated for only 5 min.
Zupp, Laurine R.,Campanella, Veronica L.,Rudzinski, Diandra M.,Beland, Franois,Priefer, Ronny
p. 5343 - 5346
(2012/10/30)

An unprecedented iron-catalyzed cross-coupling of primary and secondary alkyl Grignard reagents with non-activated aryl chlorides
The use of N-heterocyclic carbene ligands in the iron-catalyzed cross-coupling of alkyl Grignards has allowed, for the first time, coupling of non-activated, electron rich aryl chlorides. Surprisingly, the tetrahydrate of FeCl2 was found to be a better pre-catalyst than anhydrous FeCl 2. Primary Grignard reagents coupled in excellent yields while secondary Grignard reagents coupled in modest yields. The use of acyclic secondary Grignard reagents resulted in the formation of isomers in addition to the desired product. These isomeric products were formed via reversible β-hydrogen elimination, indicating that the cross-coupling proceeds through an ionic pathway.
Perry, Marc C.,Gillett, Amber N.,Law, Tyler C.
experimental part
p. 4436 - 4439
(2012/09/25)

Catalytic alkylation of aryl Grignard reagents by iron(iii) amine-bis(phenolate) complexes
Reaction of n-propylamino-N,N-bis(2-methylene-4-tert-butyl-6-methylphenol), H2L1, n-propylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H2L2, and benzylamino-N,N-bis(2-methylene-4-tert-butyl-6- methylphenol), H2L3, with anhydrous ferric chloride in the presence of base yields the products, [FeL1(μ-Cl)]2 (1), [FeL2(μ-Cl)]2 (2) and [FeL3(μ-Cl)]2 (3). In the solid state, these complexes exist as chloride-bridged dimers giving distorted trigonal bipyramidal iron(iii) ions. Reaction of H2L1 with FeBr 3, however, results in the formation of a tetrahedral iron(iii) complex possessing two bromide ligands. The amine-bis(phenolate) ligand is bidentate in this complex and bonds to the iron(iii) ion via the phenolate O-donors. The central amine donor is protonated, resulting in a quaternized ammonium fragment and the iron(iii) centre possesses a negative formal charge. As a result, this complex is zwitterionic and formulated as FeBr2L1H (4). Complex 1 is an air-stable, non-hygroscopic, single-component catalyst for C-C cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides, including chlorides. Good to excellent yields of cross-coupled products are obtained in diethyl ether at room temperature. In some cases where low yields are obtained under these conditions, the use of microwave-assisted heating of the reaction mixture can improve yields. The Royal Society of Chemistry 2011.
Qian, Xin,Dawe, Louise N.,Kozak, Christopher M.
experimental part
p. 933 - 943
(2011/04/23)

HYDROGENATION PROCESS
The present invention relates to a hydrogenation process that may be used in connection with the production of phenol. In the process, a composition comprising: (i) cyclohexylbenzene; and (ii) a hydrogenable component are contacted with hydrogen in the presence of a hydrogenation catalyst under hydrogenation conditions. The hydrogenable component can be one or more of an olefin, a ketone or phenol. The hydrogenation catalyst has hydrogenation component and a support.
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(2011/09/15)

Nickel-catalyzed Negishi cross-coupling reactions of secondary alkylzinc halides and aryl iodides
A general Ni-catalyzed process for the cross-coupling of secondary alkylzinc halides and aryl/heteroaryl iodides has been developed. This is the first process to overcome the isomerization and β-hydride elimination problems that are associated with the use of secondary nucleophiles, and that have limited the analogous Pd-catalyzed systems. The impact of salt additives was also investigated. It was found that the presence of LiBF4 dramatically improves both isomeric retention and yield for challenging substrates.(Figure Presented)
Joshi-Pangu, Amruta,Ganesh, Madhu,Biscoe, Mark R.
supporting information; experimental part
p. 1218 - 1221
(2011/04/27)

Thioether-phosphite: New ligands for the highly enantioselective Ir-catalyzed hydrogenation of minimally functionalized olefins
We have described the first successful application of non-N-donor heterodonor ligands - thioether-phosphite ligands - in the Ir-catalyzed hydrogenation of minimally functionalized olefins. Excellent enantioselectivities (ee's up to 99%) have been obtained for a range of substrates, including challenging terminal disubstituted substrates, under standard conditions.
Coll, Mercedes,Pamies, Oscar,Dieguez, Montserrat
supporting information; experimental part
p. 9215 - 9217
(2011/10/04)

Pyranoside phosphite-oxazoline ligands for the highly versatile and enantioselective Ir-catalyzed hydrogenation of minimally functionalized olefins. A combined theoretical and experimental study
A modular set of phosphite-oxazoline (P,N) ligands has been applied to the title reaction. Excellent ligands have been identified for a range of substrates, including previously challenging terminally disubstituted olefins, where we now have reached enantioselectivities of 99% for a range of substrates. The selectivity is best for minimally functionalized substrates with at least a moderate size difference between geminal groups. A DFT study has allowed identification of the preferred pathway. Computational prediction of enantioselectivities gave very good accuracy.
Mazuela, Javier,Norrby, Per-Ola,Andersson, Pher G.,Pamies, Oscar,Dieguez, Montserrat
supporting information; experimental part
p. 13634 - 13645
(2011/10/10)

Adaptative biaryl phosphite-oxazole and phosphite-thiazole ligands for asymmetrie Ir-catalyzed hydrogenation of alkenes
A library of readily available phosphite-oxazole/thiazole ligands (L1a-g-L7a-g) was applied in the Ir-catalyzed asymmetric hydrogenation of several largely unfunctionalized E- and Z-trisubstituted and 1,1-disubstituted terminal alkenes. The ability of the catalysts to transfer chiral information to the product could be tuned by choosing suitable ligand components (bridgelength, the substituents in the heterocyclic ring and the alkyl backbone chain, the configuration of the ligand backbone, and the substituents/ configurations in the biaryl phosphite moiety),so that enantioselectivities could be maximized for each substrate as required. Enantioselectivities were therefore excellent (enantiomeric excess (ee) values up to >99%) for a wide range of E- and Z-trisubstituted and 1,1-disubstituted terminal alkenes. The biaryl phosphite moiety was a very advantageous ligand component in terms of substrate versatility.
Diéguez, Montserrat,Mazuela, Javier,Paptchikhine, Alexander,Pàmies, Oscar,Andersson, Pher G.
experimental part
p. 4567 - 4576
(2010/08/07)

Bicyclic phosphine-thiazole ligands for the asymmetric hydrogenation of olefins
New bicyclic thiazole-based chiral N,P-chelating ligands were developed. High activities and enantioselectivities were achieved in the iridium-catalyzed asymmetric hydrogenation of olefins with the new ligands.
Li, Jia-Qi,Paptchikhine, Alexander,Govender, Thavendran,Andersson, Pher G.
experimental part
p. 1328 - 1333
(2010/10/21)

Iridium-catalyzed asymmetric hydrogenation of olefins using TIQ phosphine-oxazoline ligands
A novel family of tetrahydroisoquinoline (TIQ) phosphine-oxazoline ligands and four corresponding iridium complexes have been developed and applied to the asymmetric hydrogenation of unfunctionalized olefins. The results showed that the best conversion rates were observed in up to 99% with an enantiomeric excess of 91%.
Chakka, Sai Kumar,Peters, Byron K.,Andersson, Pher G.,Maguire, Glenn E.M.,Kruger, Hendrik G.,Govender, Thavendran
experimental part
p. 2295 - 2301
(2010/11/04)

Iron-catalyzed oxidative heterocoupling between aliphatic and aromatic organozinc reagents: A novel pathway for functionalized aryl-alkyl cross-coupling reactions
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Cahiez, Gerard,Foulgoc, Laura,Moyeux, Alban
supporting information; scheme or table
p. 2969 - 2972
(2009/09/06)

Helical triskelion monophosphites as ligands in asymmetric catalysis
Members of a new family of chiral triskelion P ligands, namely helical C3-symmetric monophos- phites P(OR)3, have been prepared in two steps Dy monoacylation of (R)- or (S)-1,1'-binaphthyl-2,2'-diol (BINOL) or diphenol using a carboxylic acid chloride followed Dy PCl3 phosphorylation. The most sterically hindered member of these monophosphites, derived from the compound accessible by monoacylation of BINOL using adamantane carboxylic acid chloride, has been characterized by X-ray crystallography and NMR spectroscopy as a single well-defined compound. It exists exclusively in the syn conformation, with a propeller-like (twisted) geometry resulting in helicity. Upon utilization of(R)- or (S)-BINOL in the two-step synthesis, the helicity proves to be P or M, respectively. When used as ligands in the Rh-catalyzed asymmetri c hydrogenation of prochiral homoallylic alcohols, these bulky helical ligands lead to respectable enantioselectivities (79-98percent ee). In contrast, the less sterically congested and more flexible BINOL-derived phenyl analogue exists in several conformeric forms, even in the crystal, and this leads to poor enantioselectivity in the model reactions (ee = 32percent). For the purpose of structural comparison, the analogous monophosphites derived from diphenol were also prepared and characterized. These compounds, again in contrast to the BINOL-derived adamantyl derivatives, occur in several different conformeric states.
Reetz, Manfred T.,Guo, Hongchao,Jun-An, Ma.,Goddard, Richard,Mynott, Richard J.
body text
p. 4136 - 4142
(2009/09/05)

A new efficient catalytic system for the chemoselective cobalt-catalyzed cross-coupling of aryl grignard reagents with primary and secondary alkyl bromides
(Chemical Equation Presented) The cobalt-catalyzed alkylation of aromatic Grignard reagents is performed in good yields by using a new simple and efficient catalytic system: CoCl2/TMEDA (1:1). Primary and secondary cyclic or acyclic alkyl bromides were used successfully. The reaction is highly chemoselective since ester, amide, and keto groups are tolerated. The procedure is inexpensive and very easy to carry out on a larger scale.
Cahiez, Gerard,Chaboche, Christophe,Duplais, Christophe,Moyeux, Alban
supporting information; experimental part
p. 277 - 280
(2009/08/08)

Process for making olefin oligomers and alkyl benzenes in the presence of mixed metal oxide catalysts
Provided is a process for oligomerizing n-olefins. The process has the step of reacting (oligomerizing) an amount of one or more n-olefins in the presence of a catalytically effective amount of a two or more metal oxides at a temperature effective to effect oligomerization. The two or more metal oxides are represented by the formula MOn/M′On′. M and M′, are, independently, selected from the group consisting of Al, Ce, Fe, P, W, Zr, and combinations thereof. M and M′ are different metals or combinations of metals. “n” and “n′” are positive numbers and vary stoichiometrically depending on the valency of M and M′, respectively. Provided is also a process for alkylation of an alkylatable aromatic compound. The process has the step of contacting an amount of one or more n-olefins with an amount of aromatic compound in the presence of a catalytically effective amount of the two or more metal oxides at a temperature effective to effect alkylation of the aromatic compound.
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(2009/07/10)

Hydrocarbon Conversion Process Using EMM-10 Family Molecular Sieve
This disclosure relates to a process for hydrocarbon conversion comprising contacting, under conversion conditions, a feedstock suitable for hydrocarbon conversion with a catalyst comprising an EMM-10 family molecular sieve.
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Page/Page column 16

(2009/07/10)

SELECTIVE OLIGOMERIZATION OF ISOBUTENE
A process for oligomerizing isobutene comprises contacting a feedstock comprising isobutene with a catalyst comprising a MCM-22 family molecular sieve under conditions effective to oligomerize the isobutene, wherein said conditions including a temperature from about 45°C to less than 140°C. The isobutene may be a component of a hydrocarbon feedstock containing at least one additional C4 alkene.
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(2009/05/30)