- Spontaneous resolution versus formation of racemic crystals of indenylpotassium complexes
-
During a study of stereochemically labile organometallic reagents, we found that crystallisation of [K(ind)(pmdta)]n (ind = indenyl, pmdta = N,N,N',N'',N''-pentamethyldiethylenetriamine) from tetrahydrofuran (THF) gave rise to three different crystalline phases depending on the concentration. The more concentrated solutions gave racemic crystals of the previously known coordination polymer [K(ind)(pmdta)]n, a-1. More dilute solutions gave crystals of a new phase, b-1, which was found to undergo spontaneous resolution. From even more dilute solutions, we were able to isolate a chiral inclusion compound with THF, 2, which also undergoes spontaneous resolution. Crystals of b-1 and 2 were enantiomerically pure, and since b-1 is a reactive organometallic reagent, attempts were made to use the crystals in enantioselective synthesis. Reacting single crystals with N-chlorosuccinimide gave rise to chiral 1-chloroindene, but no enantiomeric excess was observed.
- Olsson, Susanne,Lennartson, Anders,Hakansson, Mikael
-
-
Read Online
- Synthesis of borylindenides; Structure of [Li(N,N′,N″-Me3-1,3,5-C3H6N 3)][1-C9H6{B(NMe2)2}]
-
Borylation of lithium indenide (LiInd) affords indenylboranes. With BCl(NMe2)2 the primary allylic 1-indenyl derivative IndB(NMe2)2 (1) readily rearranges to the more stable vinylic bis(dimethylamino)(3-indenyl)borane 1′. With BCl(OCMe2)2 the (1-indenyl)-1,3,2-dioxaborolane IndB(OCMe2)2 (2) is obtained. Both indenylboranes 1′ and 2 readily undergo metalation when treated with lithium amides such as LiTMP or LDA to give 1-borylindenides Li[C9H6B(NMe2)2] [Li(3)] and Li[C9H6B(OCMe2)2] [Li(5)] in high yields. In the systems 1′/LiInd and 2/LiInd metalation equilibria are established with equlibrium constants K≈1 (1'/LiInd) and K≈1.4 (2/LiInd). The structure of the solvate [Li(TMHT)][1-C9H6{B(NMe2)2}] (4) (TMHT=N,N',N''-Me3-1,3,5-C3H6N3) has been confirmed by X-ray diffraction.
- Herberich, Gerhard E.,Barday, Estelle,Fischer, Andreas
-
-
Read Online
- INDENODIAZETINE: PREPARATION AND THERMAL DIAZETATION
-
The preparation of an aryl substitued diazetine and the kinetics for its thermal decomposition to nitrogen and alkene are reported.
- Pincock, J. A.,Druet, Linda M.
-
-
Read Online
- Can N-alkyl- and N-arylimidazoles be prepared directly from alcohols and phenols with N,N'-carbonyldiimidazole?
-
The report that N-alkyl- and N-arylimidazoles can be prepared directly by reactions of N,N'-carbonyldiimidazole (CDI) with alcohols or phenols was shown to be erroneous. Under the described conditions only (N-alkoxy-carbonyl)- and (N-aryloxy-carbonyl)-imi
- Fischer
-
-
Read Online
- Mehrfachbindungen zwischen Hauptgruppenelementen und Uebergangsmetallen. CXLIII. Indenyltrioxorhenium(VII): Organometalloxid mit dynamischer Struktur
-
Indenyltrioxorhenium(VII), (C9H7)ReO3, was synthesized from Re2O7 and (indenyl)tris(n-butyl)tin.It is a moisture- and temperature-sensitive compound (dec. -30 deg C), the structure of which adopts η1-coordination of the organic ligand.According to 1H NMR studies, a haptotropic structural rearrangement occurs at > -25 deg C in solution (1,3-shift mechanism).Decomposition studies show a concentration decay of the title compound in anhydrous solution, with formation of ReO3 and indene.Keywords: Rhenium; Indenyl; Dynamic structure; NMR
- Herrmann, Wolfgang A.,Kuehn, Fritz E.,Romao, Carlos C.
-
-
Read Online
- A donor-acceptor complex enables the synthesis of: E -olefins from alcohols, amines and carboxylic acids
-
Olefins are prevalent substrates and functionalities. The synthesis of olefins from readily available starting materials such as alcohols, amines and carboxylic acids is of great significance to address the sustainability concerns in organic synthesis. Metallaphotoredox-catalyzed defunctionalizations were reported to achieve such transformations under mild conditions. However, all these valuable strategies require a transition metal catalyst, a ligand or an expensive photocatalyst, with the challenges of controlling the region- and stereoselectivities remaining. Herein, we present a fundamentally distinct strategy enabled by electron donor-acceptor (EDA) complexes, for the selective synthesis of olefins from these simple and easily available starting materials. The conversions took place via photoactivation of the EDA complexes of the activated substrates with alkali salts, followed by hydrogen atom elimination from in situ generated alkyl radicals. This method is operationally simple and straightforward and free of photocatalysts and transition-metals, and shows high regio- and stereoselectivities.
- Chen, Kun-Quan,Shen, Jie,Wang, Zhi-Xiang,Chen, Xiang-Yu
-
p. 6684 - 6690
(2021/05/31)
-
- Electro-mediated PhotoRedox Catalysis for Selective C(sp3)–O Cleavages of Phosphinated Alcohols to Carbanions
-
We report a novel example of electro-mediated photoredox catalysis (e-PRC) in the reductive cleavage of C(sp3)?O bonds of phosphinated alcohols to alkyl carbanions. As well as deoxygenations, olefinations are reported which are E-selective and can be made Z-selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation, and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for an intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity-determining C(sp3)?O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions tolerate aryl chlorides/bromides and do not give rise to Birch-type reductions.
- Barham, Joshua P.,K?nig, Burkhard,Karl, Tobias A.,Reiter, Sebastian,Tian, Xianhai,Yakubov, Shahboz,de Vivie-Riedle, Regina
-
supporting information
p. 20817 - 20825
(2021/08/18)
-
- INDENE COMPOSITION
-
The present invention provides an indene composition having a content of indene of 80 to 99.5% by mass, in which a content ratio of a hydrocarbon compound having a condensed ring structure of a 5-membered ring and a 6-membered ring, and having 9 or 10 carbon atoms, in a component contained in addition to indene, is 90% by mass or more, and a content of benzonitrile is 0.5% by mass or less, and a content of sulfur is 5 ppm by mass or less.
- -
-
Paragraph 0107-0109
(2022/01/08)
-
- Mild olefin formationviabio-inspired vitamin B12photocatalysis
-
Dehydrohalogenation, or elimination of hydrogen-halide equivalents, remains one of the simplest methods for the installation of the biologically-important olefin functionality. However, this transformation often requires harsh, strongly-basic conditions, rare noble metals, or both, limiting its applicability in the synthesis of complex molecules. Nature has pursued a complementary approach in the novel vitamin B12-dependent photoreceptor CarH, where photolysis of a cobalt-carbon bond leads to selective olefin formation under mild, physiologically-relevant conditions. Herein we report a light-driven B12-based catalytic system that leverages this reactivity to convert alkyl electrophiles to olefins under incredibly mild conditions using only earth abundant elements. Further, this process exhibits a high level of regioselectivity, producing terminal olefins in moderate to excellent yield and exceptional selectivity. Finally, we are able to access a hitherto-unknown transformation, remote elimination, using two cobalt catalysts in tandem to produce subterminal olefins with excellent regioselectivity. Together, we show vitamin B12to be a powerful platform for developing mild olefin-forming reactions.
- Bam, Radha,Pollatos, Alexandros S.,Moser, Austin J.,West, Julian G.
-
p. 1736 - 1744
(2021/02/22)
-
- Mild and efficient desulfurization of thiiranes with MoCl5/Zn system
-
Desulfurization of a variety of thiiranes to alkenes occurs chemoselectively in high yields upon treatment with MoCl5/Zn system under mild conditions. The new methodology demonstrates high functional group tolerance toward chloro, bromo, fluoro, methoxy, ester, ether and keto groups.
- Lee, Yeong Jin,Shin, Jeong Won,Yoo, Byung Woo
-
-
- Thiourea-Mediated Halogenation of Alcohols
-
The halogenation of alcohols under mild conditions expedited by the presence of substoichiometric amounts of thiourea additives is presented. The amount of thiourea added dictates the pathway of the reaction, which may diverge from the desired halogenation reaction toward oxidation of the alcohol, in the absence of thiourea, or toward starting material recovery when excess thiourea is used. Both bromination and chlorination were highly efficient for primary, secondary, tertiary, and benzyl alcohols and tolerate a broad range of functional groups. Detailed electron paramagnetic resonance (EPR) studies, isotopic labeling, and other control experiments suggest a radical-based mechanism. The fact that the reaction is carried out at ambient conditions, uses ubiquitous and inexpensive reagents, boasts a wide scope, and can be made highly atom economic, makes this new methodology a very appealing option for this archetypical organic reaction.
- Mohite, Amar R.,Phatake, Ravindra S.,Dubey, Pooja,Agbaria, Mohamed,Shames, Alexander I.,Lemcoff, N. Gabriel,Reany, Ofer
-
supporting information
p. 12901 - 12911
(2020/11/26)
-
- Rhodium-Catalyzed Deoxygenation and Borylation of Ketones: A Combined Experimental and Theoretical Investigation
-
The rhodium-catalyzed deoxygenation and borylation of ketones with B2pin2 have been developed, leading to efficient formation of alkenes, vinylboronates, and vinyldiboronates. These reactions feature mild reaction conditions, a broad substrate scope, and excellent functional-group compatibility. Mechanistic studies support that the ketones initially undergo a Rh-catalyzed deoxygenation to give alkenes via boron enolate intermediates, and the subsequent Rh-catalyzed dehydrogenative borylation of alkenes leads to the formation of vinylboronates and diboration products, which is also supported by density functional theory calculations.
- Tao, Lei,Guo, Xueying,Li, Jie,Li, Ruoling,Lin, Zhenyang,Zhao, Wanxiang
-
supporting information
p. 18118 - 18127
(2020/11/26)
-
- AuCl3-Catalyzed Ring-Closing Carbonyl–Olefin Metathesis
-
Compared with the ripeness of olefin metathesis, exploration of the construction of carbon–carbon double bonds through the catalytic carbonyl–olefin metathesis reaction remains stagnant and has received scant attention. Herein, a highly efficient AuCl3-catalyzed intramolecular ring-closing carbonyl–olefin metathesis reaction is described. This method features easily accessible starting materials, simple operation, good functional-group tolerance and short reaction times, and provides the target cyclopentenes, polycycles, benzocarbocycles, and N-heterocycle derivatives in good to excellent yields.
- Wang, Rui,Chen, Yi,Shu, Mao,Zhao, Wenwen,Tao, Maoling,Du, Chao,Fu, Xiaoya,Li, Ao,Lin, Zhihua
-
supporting information
p. 1941 - 1946
(2020/02/11)
-
- Exploiting the radical reactivity of diazaphosphinanes in hydrodehalogenations and cascade cyclizations
-
The remarkable reducibility of diazaphosphinanes has been extensively applied in various hydrogenations, based on and yet limited by their well-known hydridic reactivity. Here we exploited their unprecedented radical reactivity to implement hydrodehalogenations and cascade cyclizations originally inaccessible by hydride transfer. These reactions feature a broad substrate scope, high efficiency and simplicity of manipulation. Mechanistic studies suggested a radical chain process in which a phosphinyl radical is generated in a catalytic cycle via hydrogen-atom transfer from diazaphosphinanes. The radical reactivity of diazaphosphinanes disclosed here differs from their well-established hydridic reactivity, and hence, opens a new avenue for diazaphosphinane applications in organic syntheses.
- Cheng, Jin-Pei,Yang, Jin-Dong,Zhang, Jingjing
-
p. 4786 - 4790
(2020/06/18)
-
- Ligand Substitution of RuII–Alkylidenes to Ru(bpy)32+: Sequential Olefin Metathesis/Photoredox Catalysis
-
Ruthenium(II) alkylidene complexes such as the Grubbs’ 1st and 2nd generation catalysts undergo a ligand substitution with 2,2′-bipyridine, which readily leads to the common photoredox catalyst Ru(bpy)32+. The application of this catalyst transformation in sequential olefin metathesis/photoredox catalysis is demonstrated by way of ring-closing metathesis (RCM)/photoredox ATRA reactions.
- Gallhof, Malte,Kell, Lukas,Brasholz, Malte
-
supporting information
p. 1772 - 1775
(2020/02/05)
-
- Selective and efficient desulfurization of thiiranes with Mo(CO)6
-
Mo(CO)6 converts a broad range of thiiranes to the corresponding alkenes in high yields under neutral conditions. It has been found that this protocol is chemoselective and tolerates a variety of functional groups such as chloro, bromo, fluoro, ester, methoxy, ether and keto.
- Yoo, Byung Woo,Kim, Jung Youn
-
-
- PRODUCTION METHOD OF INDENE
-
PROBLEM TO BE SOLVED: To provide a dehydrogenation method of indane, which is capable of efficiently producing indene from indane, as a novel production method of the indene. SOLUTION: A production method of indene, which includes a dehydrogenation step of obtaining a reaction product containing indene, by bringing a raw material gas containing indane and molecular hydrogen into contact with a dehydrogenation catalyst, in which the dehydrogenation catalyst has a carrier containing aluminum and a carrier metal carried by the carrier, the carrier metal contains a 14-th group metal element and platinum, and an atomic ratio of the 14-th group element to the platinum in the dehydrogenation catalyst is 8.0 or smaller. SELECTED DRAWING: None COPYRIGHT: (C)2020,JPO&INPIT
- -
-
Paragraph 0050-0068
(2019/12/25)
-
- Carbonyl-Olefin Metathesis Catalyzed by Molecular Iodine
-
The carbonyl-olefin metathesis reaction could facilitate rapid functional group interconversion and allow construction of complicated organic structures. Herein, we demonstrate that elemental iodine, a very simple catalyst, can efficiently promote this chemical transformation under mild reaction conditions. Our mechanistic studies revealed intriguing aspects of the activation mode via molecular iodine and the iodonium ion that could change the previously established perception of catalyst and substrate design for the carbonyl-olefin metathesis reaction.
- Tran, Uyen P. N.,Oss, Giulia,Breugst, Martin,Detmar, Eric,Pace, Domenic P.,Liyanto, Kevin,Nguyen, Thanh V.
-
p. 912 - 919
(2019/01/14)
-
- Organocatalytic Chlorination of Alcohols by P(III)/P(V) Redox Cycling
-
A catalytic system for the chlorination of alcohols under Appel conditions was developed. Benzotrichloride is used as a cheap and readily available chlorinating agent in combination with trioctylphosphane as the catalyst and phenylsilane as the terminal reductant. The reaction has several advantages over other variants of the Appel reaction, e.g., no additional solvent is required and the phosphane reagent is used only in catalytic amounts. In total, 27 different primary, secondary, and tertiary alkyl chlorides were synthesized in yields up to 95%. Under optimized conditions, it was also possible to convert epoxides and an oxetane to the dichlorinated products.
- Longwitz, Lars,Jopp, Stefan,Werner, Thomas
-
supporting information
p. 7863 - 7870
(2019/06/27)
-
- Thermal Behavior Analysis of Two Synthesized Flavor Precursors of N-alkylpyrrole Derivatives
-
To expand the library of pyrrole-containing flavor precursors, two new flavor precursors—methyl N-benzyl-2-methyl-5-formylpyrrole-3-carboxylate (NBMF) and methyl N-butyl-2-methyl-5-formylpyrrole-3-carboxylate (NUMF)—were synthesized by cyclization, oxidation, and alkylation reactions. Thermogravimetry (TG), differential scanning calorimeter, and pyrolysis–gas chromatography/mass spectrometry were utilized to analyze the thermal degradation behavior and thermal degradation products of NBMF and NUMF. The TG-DTG curve indicated that the maximum mass loss rates of NBMF and NUMF appear at 310 and 268°C, respectively. The largest peaks of NBMF and NUMF showed by the differential scanning calorimeter curve were 315 and 274°C, respectively. Pyrolysis–gas chromatography/mass spectrometry detected small molecule fragrance compounds appeared during thermal degradation, such as 2-methylpyrrole, 1-methylpyrrole-2-carboxylic acid methyl ester, limonene, and methyl formate. Finally, the thermal degradation mechanism of NBMF and NUMF was discussed, which provided a theoretical basis for their application in tobacco flavoring additives.
- Ai, Lvye,Liu, Mengzhen,Ji, Xiaoming,Lai, Miao,Zhao, Mingqin,Ren, Tianbao
-
p. 2389 - 2397
(2019/08/01)
-
- Carbocation catalysed ring closing aldehyde-olefin metathesis
-
A highly efficient aldehyde-olefin metathesis catalysed by the carbocation, 4-phenylphenyl-diphenylmethylium ion, has been developed. This protocol is characterized by high yields, low catalyst loading (down to 2 mol%), good functional group compatibility and mild reaction conditions.
- Ni, Shengjun,Franzén, Johan
-
supporting information
p. 12982 - 12985
(2018/11/23)
-
- Efficient and selective hydrogenation of C-O bonds with a simple sodium formate catalyzed by nickel
-
A Ni-catalyzed hydrogenation of C-O compounds with sodium formate is developed. Various esters, i.e. aryl, alkenyl, benzyl pivalates, and even the aryl ethers, were efficiently reduced with a loading of nickel catalysts down to 0.5 mol%. Reactive functional groups such as C-C double bonds, carbonyl, CN, MeS and halogen groups are tolerable. This reaction can be used for the modification of complex molecules and carried out at a large scale.
- Xi, Xiaoxiang,Chen, Tieqiao,Zhang, Ji-Shu,Han, Li-Biao
-
supporting information
p. 1521 - 1524
(2018/02/19)
-
- Role of σ,π-Digold(I) Alkyne Complexes in Reactions of Enynes
-
Gold(I) acetylide and σ,π-digold(I) alkyne complexes derived from one prototypical 1,6-enyne and from 7-ethynyl-1,3,5-cycloheptatriene have been prepared and structurally characterized. Their possible role in gold(I)-catalyzed cycloisomerizations has been studied by experiment and by DFT calculations. Gold(I) acetylides are totally unproductive complexes in the absence of Br?nsted acids. Similarly, no cyclizations were observed by heating σ,π-digold(I) alkyne digold(I) at least up to 130 °C. Theoretical studies provide a rationale for the much lower reactivity of digold species in reactions of enynes.
- Ferrer, Sofia,Echavarren, Antonio M.
-
supporting information
p. 781 - 786
(2018/03/21)
-
- Rapid and efficient debromination of vic-dibromides with VCl3/indium system
-
The VCl3/In system was found to be a new protocol for debromination of a variety of vic-dibromides to the corresponding alkenes in high yields with short reaction times under mild conditions. This new methodology is highly chemose-lective, tolerating several functional groups such as chloro, bromo, fluoro, keto, ester, carboxyl, and methoxy groups.
- Woo Yoo, Byung,Yeon Park, Jee,Jong Shin, Hyo
-
p. 275 - 278
(2018/08/21)
-
- Competitive, substrate-dependent reductive debromination/dehydrobromination of 1,2-dibromides with triethylamine
-
The interaction of various 1,2-dibromides with NEt3 under various conditions (THF and DMF, respectively) at different temperatures was investigated. Our results from these reactions show that substrate dependent dehydrobrominations compete with reductive debrominations. A comprehensive discussion of these competitive pathways is offered.
- McGraw, Kristen M.,Kent, Greggory T.,Gonzalez, Joseph R.,Erden, Ihsan,Wu, Weiming
-
p. 1973 - 1975
(2017/04/27)
-
- Products of the Propargyl Self-Reaction at High Temperatures Investigated by IR/UV Ion Dip Spectroscopy
-
The propargyl radical is considered to be of key importance in the formation of the first aromatic ring in combustion processes. Here we study the bimolecular (self-) reactions of propargyl in a high-temperature pyrolysis flow reactor. The aromatic reaction products are identified by IR/UV ion dip spectroscopy, using the free electron laser FELIX as mid-infrared source. This technique combines mass selectivity with structural sensitivity. We identified several aromatic reaction products based on their infrared spectra, among them benzene, naphthalene, phenanthrene, indene, biphenyl, and surprisingly a number of aromatic compounds with acetylenic (ethynyl) side chains. The observation of benzene confirms that propargyl is involved in the formation of the first aromatic ring. The observation of compounds with acetylenic side chains shows that, in addition to a propargyl- and phenyl-based mechanism, the HACA (hydrogen abstraction C2H2 addition) mechanism of polycyclic aromatic hydrocarbons formation is present, although no acetylene was used as a reactant. On the basis of the experimental results we suggest a mechanism that connects the two pathways.
- Constantinidis,Hirsch,Fischer,Dey,Rijs
-
p. 181 - 191
(2017/06/07)
-
- Simple synthesis method of olefin
-
The invention discloses a simple synthesis method of olefin, and relates to the technical field of preparation of an organic compound, i.e., olefin. The olefin is prepared by taking tertiary alcohol as a raw material, sodium bisulfate monohydrate as a catalyst and water as a solvent. Compared with the conventional method, the method provided by the invention has the advantages that the raw materials are simple and readily available, the cost is low, the process time is short, the reaction conditions are mild, and the reaction is easy to operate; the simple synthesis method is a simple method for synthesizing an olefin compound.
- -
-
Paragraph 0012; 0019; 0020
(2017/04/28)
-
- Reductive debromination of 1,2-dibromides with anisidines
-
vic-Dibromides containing the α-bromocarbonyl or α-bromoaromatic moieties were reductively debrominated to furnish alkenes in high yields. o- and m-anisidines but not p-anisidine were found to be effective debrominating agents. The reductive debrominations were found to be trans-stereospecific.
- McGraw, Kristen M.,Bowler, Jeannette T.,Ly, Vy T.,Erden, Ihsan,Wu, Weiming
-
p. 285 - 287
(2016/01/12)
-
- Study of the Formation of the First Aromatic Rings in the Pyrolysis of Cyclopentene
-
The thermal decomposition of cyclopentene was studied in a jet-stirred reactor operated at constant pressure and temperature to provide new experimental information about the formation of the first aromatic rings from cyclic C5 species. Experim
- Herbinet, Olivier,Rodriguez, Anne,Husson, Benoit,Battin-Leclerc, Frédérique,Wang, Zhandong,Cheng, Zhanjun,Qi, Fei
-
p. 668 - 682
(2016/02/23)
-
- Enhancement of hydrocarbon production and catalyst stability during catalytic conversion of biomass pyrolysis-derived compounds over hierarchical HZSM-5
-
In order to promote hydrocarbon production and catalyst stability in catalytic fast pyrolysis (CFP) of biomass, HZSM-5 catalysts were treated with alkali solutions to introduce mesopores into the microporous system. Parent and hierarchical catalysts were tested in catalytic conversion of furan as an important intermediate from biomass fast pyrolysis (BFP). Controlled desilication with mole concentration of NaOH of 0.3 M resulted in sheet-like mesopores on the external sphere, enhancing mass transfer in the catalyst, and it specifically promoted the carbon yield of hydrocarbons by 21.6%. Though the coke content on these HZSM-5-0.3M catalysts increased gradually by 11.6%, the tolerance toward deactivation by coke deposition was improved. Cyclic tests of catalysis-regeneration process over hierarchical HZSM-5-0.3M over 20 cycles revealed that it can withstand long-running with a stable yield of hydrocarbons being achieved. Thus, hierarchical HZSM-5 is a suitable catalyst for CFP of biomass and its derivatives to hydrocarbons by this simple synthetic process.
- Shao,Zhang,Shen,Xiao
-
p. 44313 - 44320
(2016/06/09)
-
- Metallocenes and Catalyst Compositions Derived Tehrefrom
-
This invention relates to a novel group 2, 3 or 4 transition metal metallocene catalyst compound that is asymmetric having two non-identical indenyl ligands with substitution at R2 having a branched or unbranched C1-C20 alkyl group substituted with a cyclic group or a cyclic group, R8 is an alkyl group and R4 and R10 are substituted phenyl groups.
- -
-
Page/Page column
(2015/02/18)
-
- CATALYSTS
-
A catalyst comprising (i) an asymmetric complex of formula (I) wherein M is zirconium or hafnium; each X is a sigma ligand; L is a divalent bridge selected from —R′2C—, —R′2C—CR′2—, —R′2Si—, —R′2Si—SiR′2—, —R′2Ge—, wherein each R′ is independently a hydrogen atom, C1-C20-alkyl, tri(C1-C20-alkyl)silyl, C6-C20-aryl, C7-C20-arylalkyl or C7-C20-alkylaryl; R2 and R2′ are each independently linear C1-10 hydrocarbyl; R5 and R5′ are each independently hydrogen or a C1-20 hydrocarbyl group; R6 and R6′ are each independently hydrogen or a C1-20 hydrocarbyl group; R7 is hydrogen or a C1-20 hydrocarbyl group or is ZR3; Z is O or S, preferably O; R3 is a C1-10 hydrocarbyl group; Ar is an aryl or heteroaryl group having up to 20 carbon atoms optionally substituted by one or more groups R8; Ar′ is an aryl or heteroaryl group having up to 20 carbon atoms optionally substituted by one or more groups R8′; and R8 and R8′ are each independently is a C1-20 hydrocarbyl group; with the proviso that at least one of R6 or R7 is not H; and (ii) a cocatalyst comprising a compound of a group 13 metal, e.g. boron.
- -
-
-
- Understanding Precatalyst Activation in Cross-Coupling Reactions: Alcohol Facilitated Reduction from Pd(II) to Pd(0) in Precatalysts of the Type (η3-allyl)Pd(L)(Cl) and (η3-indenyl)Pd(L)(Cl)
-
Complexes of the type (η3-allyl)Pd(L)(Cl) (L = PR3 or NHC), have been used extensively as precatalysts for cross-coupling and related reactions, with systems containing substituents in the 1-position of the η3-allyl ligand, such as (η3-cinnamyl)Pd(L)(Cl), giving the highest activity. Recently, we reported a new precatalyst scaffold based on an η3-indenyl ligand, (η3-indenyl)Pd(L)(Cl), which typically provides higher activity than even η3-cinnamyl supported systems. In particular, precatalysts of the type (η3-1-tBu-indenyl)Pd(L)(Cl) give the highest activity. In cross-coupling reactions using this type of Pd(II) precatalyst, it is proposed that the active species is monoligated Pd(0), and the rate of reduction to Pd(0) is crucial. Here, we describe detailed experimental and computational studies which explore the pathway by which the Pd(II) complexes (η3-allyl)Pd(IPr)(Cl) (IPr = 1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene), (η3-cinnamyl)Pd(IPr)(Cl), (η3-indenyl)Pd(IPr)(Cl) and (η3-1-tBu-indenyl)Pd(IPr)(Cl) are reduced to Pd(0) in alcoholic solvents, which are commonly used in Suzuki-Miyaura and α-arylation reactions. The rates of reduction for the different precatalysts are compared and we observe significant variability based on the exact reaction conditions. However, in general, η3-indenyl systems are reduced faster than η3-allyl systems, and DFT calculations show that this is in part due to the ability of the indenyl ligand to undergo facile ring slippage. Our results are consistent with the η3-indenyl systems giving increased catalytic activity and provide fundamental information about how to design systems that will rapidly generate monoligated Pd(0) in the presence of alcohols.
- Melvin, Patrick R.,Balcells, David,Hazari, Nilay,Nova, Ainara
-
p. 5596 - 5606
(2015/09/15)
-
- CO extrusion in homogeneous gold catalysis: Reactivity of gold acyl species generated through water addition to gold vinylidenes
-
Herein, we describe a new gold-catalyzed decarbonylative indene synthesis. Synergistic σ,π-activation of diyne substrates leads to gold vinylidene intermediates, which upon addition of water are transformed into gold acyl species, a type of organogold compound hitherto only scarcely reported. The latter are shown to undergo extrusion of CO, an elementary step completely unknown for homogeneous gold catalysis. By tuning the electronic and steric properties of the starting diyne systems, this new reactivity could be exploited for the synthesis of indene derivatives in high yields.
- Bucher, Janina,St?sser, Tim,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
-
supporting information
p. 1666 - 1670
(2015/01/30)
-
- Mild deprotection of PMB ethers using tert-butyl bromide
-
A convenient and high yielding method for the cleavage and scavenging of p-methoxybenzyl protecting group of several alcohols using tert-butyl bromide in refluxing acetonitrile is described. Under these mild conditions other protecting groups such as acid sensitive allyl, benzyl, and Me3CPh2Si ethers, or isopropylidene acetals were unchanged. Interestingly, a selective alkoxy-PMB cleavage was observed in the presence of a PMB phenoxy ether.
- Rival, Nicolas,Albornoz Grados, Arantxa,Schiavo, Lucie,Colobert, Fran?oise,Hanquet, Gilles
-
p. 6823 - 6826
(2015/11/27)
-
- Homogeneous catalysis and selectivity in electrochemistry
-
The relationship between homogeneous catalysis and electrochemistry is examined in light of two examples based on our work concerning (a) catalyst activation, regarding selective electrochemical C-H oxidation with RuIII/RuIV mediation, and (b) catalyst suppression, regarding controlling selectivity in electrochemical aromatic chlorination. The first example (a) deals with the role of catalysis at the working electrode. The electrochemical (EC) oxidation of specific hydrocarbons such as tetralin and indane is performed using tris(acetonitrile)ruthenium trichloride (Ru(CH3CN)3Cl3) as a mediator. The role of this mediator in the oxidation of tetralin has been reported. This homogeneous C-H activation by electron transfer (ET) is accompanied by the redox transitions of the mediator in the course of the catalytic oxidation, and these are the main points of interest here. Additional studies with a rotating ring disk electrode (RRDE) provided a follow-up of creation and recovery of RuIII/RuII and RuIII/RuIV species in the process. Using electrochemistry linked with electrospray ionization mass spectrometry (EC/ESI-MS) gave additional information on the structure of the reduced and oxidized forms of Ru(CH3CN)3Cl3 and the effect of water in the solvent on their lifetimes. The second example (b) of electrochlorination has been reported elsewhere and is brought up as complementary remarks. Aromatic electrophilic chlorination of 1,4-dimethoxy-2-tertbutylbenzene is autocatalyzed and unselective. The EC procedure provides a simple means to inhibit the catalytic runaway reaction. This example shows how the counter electrode affects catalysis and selectivity. (Figure Presented)
- Michman, Michael,Appelbaum, Lina,Gun, Jenny,Modestov, Alexander D.,Lev, Ovadia
-
p. 4729 - 4737
(2015/04/27)
-
- Catalyst
-
A catalyst comprising (i) an asymmetric complex of formula (I) wherein M is zirconium or hafnium; each X is a sigma ligand; L is a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-SiR'2-, -R'2Ge-, wherein each R' is independently a hydrogen atom, C1-C20-alkyl, tri(C1-C20-alkyl)silyl, C6-C20-aryl, C7-C20-arylalkyl or C7-C20-alkylaryl; R2 and R2' are each independently linear C1-10 hydrocarbyl; R5 and R5' are each independently hydrogen or a C 1-20 hydrocarbyl group; R6 and R6' are each independently hydrogen or a C1-20 hydrocarbyl group; R7 is hydrogen or a C1-20 hydrocarbyl group or is ZR3; Z is O or S, preferably O; R3 is a C1-10 hydrocarbyl group; Ar is an aryl or heteroaryl group having up to 20 carbon atoms optionally substituted by one or more groups R8; Ar' is an aryl or heteroaryl group having up to 20 carbon atoms optionally substituted by one or more groups R8'; R8 and R8' are each independently is a C1-20 hydrocarbyl group; with the proviso that at least one of R6 or R7 is not H; and (ii) a cocatalyst comprising a compound of a group 13 metal, e.g. boron.
- -
-
Page/Page column
(2014/07/08)
-
- Unexpected pyrolytic behaviour of substituted benzo[c]thiopyran and thieno[2,3-c]thiopyran s,s-dioxides
-
Flash vacuum pyrolysis (FVP) of benzo[c]thiopyran S,S-dioxide (1) results in formation of indene and 2-vinylbenzaldehyde as previously described. A range of eight analogues with various substitution patterns are found to behave differently. In general, there is no extrusion of SO2 to give products analogous to indene, but unsaturated carbonyl products analogous to 2-vinylbenzaldehyde are formed in most cases by way of ring expansion to a 7-membered ring sultine, extrusion of SO, and intramolecular hydrogen atom transfer. Other processes observed include formation of anthracene via an isomeric 7-membered sultine with loss of SO, CO and methane or butane, and formation of 4-ethylidene-4,5- dihydrocyclobuta[b]thiophenes by way of SO loss, a radical rearrangement, and extrusion of acetone. The analogues with a halogen substituent at position 8 on the benzene ring require a higher temperature to react and give naphthalene resulting from net elimination of HX and SO2. The X-ray crystal structure of 1 is also reported.
- Aitken, R. Alan,Hauduc, Clemence,Hossain, M. Selim,McHale, Emily,Schwan, Adrian L.,Slawin, Alexandra M. Z.,Stewart, Colin A.
-
p. 1288 - 1295
(2014/11/07)
-
- Microwave flash pyrolysis: C9h8 interconversions and dimerisations
-
The pyrolysis of 2-ethynyltoluene, indene, fluorene, and related compounds has been studied by sealed tube microwave flash pyrolysis (MFP), in concert with modelling of putative mechanistic pathways by density functional theory (DFT) computations. In the MFP technique, samples are admixed with graphite and subjected to intense microwave power (150-300 W) in a quartz reaction tube under a nitrogen atmosphere. The MFP reaction of 2-ethynyltoluene gave mostly indene, the product of a Roger Brown rearrangement (1,2-H shift to a vinylidene) followed by insertion. An additional product was chrysene, the likely result of hydrogen atom loss from indene followed by dimerisation. The intermediacy of dimeric bi-indene structures was supported by pyrolysis of bi-indene and by computational models. Benzo[a]anthracene and benzo[c]phenanthrene are minor products in these reactions. These are shown to arise from pyrolysis of chrysene under the same MFP conditions. MFP reaction of fluorene gave primarily bi-fluorene, bifluorenylidene, and dibenzochrysene, the latter derived from a known Stone-Wales rearrangement.
- Ajaz, Aida,Voukides, Alicia C.,Cahill, Katharine J.,Thamatam, Rajesh,Skraba-Joiner, Sarah L.,Johnson, Richard P.
-
p. 1301 - 1308
(2014/11/07)
-
- The effect of water on furan conversion over ZSM-5
-
Catalytic fast pyrolysis is a method for converting lignocellulosic biomass into renewable aromatics and olefins. Water is a byproduct of this reaction and is also present in the biomass feed. As the water partial pressure is increased from 0 to 212Torr (0 to 28kPa), there is an increase in furan conversion from 43.8 to 84.8% over ZSM-5. The CO2 and propylene yields also increase from 0.7 to 16.4% and 2.9 to 44.9%, respectively, as the water partial pressure increases. Water partial pressures in an industrial catalytic fast pyrolysis reactor should be within the range of water partial pressures used in this study. These results demonstrate that the presence of water promotes hydrolysis reactions in the gas-phase conversion of furanic pyrolysis vapors over zeolite catalysts.
- Gilbert, Christopher J.,Espindola, Juliana S.,Conner, William C.,Trierweiler, Jorge O.,Huber, George W.
-
p. 2497 - 2500
(2015/04/14)
-
- An efficient catalyst based on manganese salen for hydrosilylation of carbonyl compounds
-
A manganese salen complex is shown to be an effective (pre)catalyst in the hydrosilylation of aldehydes and ketones. The present system features an earth-abundant and inexpensive base metal, low catalyst loading, and functional group tolerance. Mechanistic studies suggest that the reaction likely proceeds through a reduced manganese(III) hydride species that undergoes electrophilic attack by the carbonyl substrates.
- Chidara, Vamshi K.,Du, Guodong
-
supporting information
p. 5034 - 5037
(2013/10/08)
-
- Doped graphene as a metal-free carbocatalyst for the selective aerobic oxidation of benzylic hydrocarbons, cyclooctane and styrene
-
Nitrogen (N)-, boron (B)-, and boron,nitrogen (B,N)-doped graphene (G) act as carbocatalysts, promoting the aerobic oxidation of the benzylic positions of aromatic hydrocarbons and cyclooctane to the corresponding alcohol/ketone mixture with more than 90 % selectivity. The most active material was the co-doped (B,N)G, which, in the absence of solvent and with a substrate/(B,N)G ratio of 200, achieved 50 % tetralin conversion in 24 h with a alcohol/ketone selectivity of 80 %. An FT-Raman spectroscopic study of a sample of (B,N)G heated at 100 °C in the presence of oxygen revealed new bands that disappeared upon evacuation and that have been attributed to hydroperoxide-like species formed on the G sheet based on the isotopic shift of the peak from 819 to 779 cm-1 when 18O2 was used as the oxidizing reagent. Furthermore, (B)G and (N)G exhibited high catalytic activity in the aerobic oxidation of styrene to benzaldehyde (BA) in 4 h. However, the product distribution changed over time and after 10 h a significant percentage of styrene oxide (SO) was observed under the same conditions. The use of doped G as catalyst appears to offer broad scope for the aerobic oxidation of benzylic compounds and styrene, for which low catalyst loading, mild reaction temperatures, and no additional solvents are required. Oxidation at graphene: Boron- and nitrogen-doped graphenes are excellent catalysts for promoting the oxidation of benzylic hydrocarbons, cyclooctane, and styrene with molecular oxygen at 0.5 wt % under atmospheric pressure and solvent-free conditions (see figure). Copyright
- Dhakshinamoorthy, Amarajothi,Primo, Ana,Concepcion, Patricia,Alvaro, Mercedes,Garcia, Hermenegildo
-
p. 7547 - 7554
(2013/07/11)
-
- Synthesis, properties, and reactivity of palladium and nickel NHC complexes supported by combinations of allyl, cyclopentadienyl, and indenyl ligands
-
The synthesis of a series of Pd and Ni complexes containing combinations of 2-methylallyl (C4H7), cyclopentadienyl (C 5H5, Cp), and indenyl (C7H9, Ind) ligands is reported. In all cases these complexes are supported by the electron-donating N-heterocyclic carbene ligand 1,3-bis(2,6-diisopropylphenyl)- 1,3-dihydro-2H-imidazol-2-ylidene (IPr). The mixed Cp/2-methylallyl complexes (η1-Cp)(η3-2-methylallyl)Pd(IPr) ( CpAllPd) and (η5-Cp)(η1-2-methylallyl) Ni(IPr) (CpAllNi) were synthesized through the reaction of IPr with (Cp)(2-methylallyl)M (M = Ni, Pd). The binding mode of the ligands is different in the two complexes, and as a result the total valence electron count around the metal is 18 for the Ni complex and only 16 for the Pd species. In the case of Pd, an analogue of CpAllPd containing an indenyl ligand, (η1-Ind)(η3-2-methylallyl)Pd(IPr) ( IndAllPd), was synthesized through the reaction of (η3-Ind)Pd(IPr)Cl (IndClPd) with (2-methylallyl) magnesium chloride. The corresponding Ni complex (η5-Ind) (η1-2-methylallyl)Ni(IPr) (IndAllNi) could not be isolated. The binding modes of the ligands in the mixed indenyl/Cp complexes (η1-Ind)(η5-Cp)M(IPr) (M = Ni ( IndCpNi), Pd (IndCpPd)) were the same for both Ni and Pd. IndCpPd was prepared through the reaction of IndClPd with NaCp, while IndCpNi was synthesized through the reaction of (η5-Cp)Ni(IPr)Cl (CpClNi) with lithium indenyl. Similarly, the structures of the bis(Cp) complexes (η5-Cp) (η1-Cp)Ni(IPr) (CpCpNi) and (η5-Cp) (η1-Cp)Pd(IPr) (CpCpPd) were identical for the two different metals. In contrast to CpCpPd, which is an 18-electron complex, the related bis(indenyl) Pd complex (η3-Ind) (η1-Ind)Pd(IPr) (IndIndPd) is a 16-electron species, while no Ni analogue of IndIndPd was characterized. Preliminary reactivity studies with electrophiles indicate that, in all systems with mixed ligands, the η1-ligand is nucleophilic and reacts selectively. The complexes CpAllPd, CpAllNi, CpCpPd, CpCpNi, IndClPd, IndAllPd, and IndIndPd were characterized by X-ray crystallography.
- Bielinski, Elizabeth A.,Dai, Wei,Guard, Louise M.,Hazari, Nilay,Takase, Michael K.
-
p. 4025 - 4037
(2013/09/02)
-
- Graphite oxide: An efficient reagent for oxidation of alcohols under sonication
-
Graphite oxide (GO) was used as an effective oxidizing agent for the synthesis of aldehydes and ketones from various alcohols under ultrasonic irradiation. Under optimized conditions, quantitative yields of the products were obtained. Compared to other reagents used for the same chemical transformation, GO displays several advantages, including low cost, ease of synthesis, and high stability to ambient conditions.
- Mirza-Aghayan, Maryam,Kashef-Azar, Elnaz,Boukherroub, Rabah
-
p. 4962 - 4965
(2012/11/07)
-
- Solvent-free dehydration of alcohols using LiCI-acidicalumina
-
Conjugated enynes, dienes and simple olefins have been cleanly and selectively synthesized, good-to-excellent yields, by dehydration of corresponding alcohols using focused microwave irradiation on the surface of LiCI-acidic alumina.
- Bagheri Marandi,Pourjavadi,Hosseinzadeh
-
p. 1141 - 1145
(2013/02/25)
-
- Catalytic fast pyrolysis of wood and alcohol mixtures in a fluidized bed reactor
-
Catalytic fast pyrolysis (CFP) of pine wood, alcohols (methanol, 1-propanol, 1-butanol and 2-butanol) and their mixtures with ZSM-5 catalyst were conducted in a bubbling fluidized bed reactor. The effects of temperature and weight hourly space velocity (WHSV) on the product carbon yields and selectivities of CFP of pure pine wood and methanol were investigated. A maximum carbon yield of petrochemicals (aromatics + C2-C4 olefins + C5 compounds) from pine wood of 23.7% was obtained at a temperature of 600 °C and WHSV of 0.35 h-1. A maximum petrochemical yield from methanol of 80.7% was obtained at a temperature of 400 °C and WHSV of 0.35 h-1. Thus, the optimal conditions for conversion of pine wood and methanol are different. The CFP of pine wood and methanol mixtures was conducted at 450 °C and 500 °C. The hydrogen to carbon effective (H/Ceff) ratio of the feed was adjusted by changing the relative amount of methanol and wood. The petrochemical yield was a function of the H/Ceff ratio and more petrochemicals are produced from biomass when methanol is added to the CFP process. Co-feeding of 12C pine wood and 13C methanol was carried out at 450 °C. The isotopic study showed that all the hydrocarbon products contained mixtures of 12C and 13C, indicating that the carbon is mixed within the zeolite. However, the distribution of carbon was skewed depending on the product. The toluene, xylene, propylene and butenes contained more 13C. The naphthalene and ethylene contain more 12C. Wood was also co-processed with 1-propanol, 1-butanol, and 2-butanol, which showed a similar effect as methanol with an increasing petrochemical yield with an increasing H/Ceff ratio of the feed. This paper demonstrates that CFP can selectively produce a mixture of compounds where the overall yield is a function of the H/Ceff ratio of the feed.
- Zhang, Huiyan,Carlson, Torren R.,Xiao, Rui,Huber, George W.
-
experimental part
p. 98 - 110
(2012/04/04)
-
- Pyrolytic formation of polycyclic aromatic hydrocarbons from sesquiterpenes
-
The products of the pyrolysis of four sesquiterpenes, β-caryophyllene, α-cedrene, longifolene and valencene, have been examined. Pyrolysis was carried out at 300, 400 and 500 °C, the products determined by GC-MS and then examined for similarities and diff
- Francis, George W.,Christy, Alfred A.,Oygarden, Jostein
-
p. 1316 - 1322
(2012/11/06)
-
- Dehydration of benzyl alcohols in phosphonium ionic liquids: Synthesis of ethers and alkenes
-
The dehydration of benzylic alcohols has been studied in several phosphonium ionic liquids in the absence of any metal catalysts. Benzyl ethers and alkenes were obtained from primary and secondary benzylic alcohols in good to excellent yields for these reactions. Commercially available hydrophobic phosphonium ionic liquids containing the trihexyl(tetradecyl)phosphonium cation paired with six different anions were used for the reactions under microwave irradiation. The interaction of the substrate with the ionic liquid was investigated using different NMR techniques, such as NOESY NMR. The effects of cation and anions on the behaviour of these ionic liquids in the reactions were studied in order to understand the mechanism. A catalytic cycle is proposed involving activation of the benzyl alcohol by the phosphonium cation. Copyright
- Kalviri, Hassan A.,Kerton, Francesca M.
-
experimental part
p. 3178 - 3186
(2012/01/03)
-
- Transesterification catalyzed by iron(III) β-diketonate species
-
A practical and clean protocol for transesterification catalyzed by a 5 mol % cheap, non-toxic and moisture stable Fe(acac)3 or other iron(III) β-diketonate species in solvent, such as heptane under azeotropic condition is developed. A remarkable rate enhancement was observed upon the addition of 5 mol % of an inorganic base, such as Na2CO3, which suggests that faster formation of a dimeric μ-alkoxy-bridged iron(III) species under alkaline conditions facilitates catalytic turnover. This system provides smooth transesterification over a wide range of structurally diverse esters and alcohols without disturbing functional groups. In addition, the use of iron β-diketonate complexes as catalysts is more environmentally friendly, safer, and economical than other transition-metal catalysts. Preliminary mechanistic studies indicate that the active catalyst is likely a dimeric μ-alkoxy-bridged iron(III) species, as determined by X-ray crystallography of [Fe(dbm)2(O-n-Bu)]2 derived from the alcoholysis of Fe(dbm)3 under alkaline conditions.
- Weng, Shiue-Shien,Ke, Chih-Shueh,Chen, Fong-Kuang,Lyu, You-Fu,Lin, Guan-Ying
-
experimental part
p. 1640 - 1648
(2011/04/17)
-
- Pyrolytic hydrocarbon growth from cyclopentadiene
-
Aromatic hydrocarbon growth from cyclopentadiene (CPD) was studied using a laminar flow reactor operating in the temperature range 550-950 °C without oxygen. Benzene, indene, and naphthalene were the major products, which is in agreement with the previous computational studies on the reaction pathways from CPD. A crossover of indene and naphthalene yields around 775 °C was also observed, which further supports the results of the computational studies. Although the specific intermediates in the proposed pathways from CPD were not detected, the high selectivity of products and the observation of other methylindene and dihydronaphthalene intermediates suggest that the recombination of two CPDs via radical-molecule and/or radical-radical pathways to form indene and naphthalene is the dominant formation pathway. In addition to the products from the CPD-CPD reactions, the products from the reactions of CPD with indene, naphthalene, and acenaphthylene were also observed, which demonstrate the importance of CPD in carbon growth.
- Kim, Do Hyong,Mulholland, James A.,Wang, Dong,Violi, Angela
-
experimental part
p. 12411 - 12416
(2011/02/28)
-
- RACEMOSELECTIVE SYNTHESIS OF ANSA-METALLOCENE COMPOUNDS, ANSA-METALLOCENE COMPOUNDS, CATALYSTS COMPRISING THEM, PROCESS FOR PRODUCING AN OLEFIN POLYMER BY USE OF THE CATALYSTS, AND OLEFIN HOMO- AND COPOLYMERS
-
A metallocene compound with the 4- and 7-positions on the indenyl moiety possessing large aromatic substituents is prepared in accordance with a method which produces substantially 100 percent racemic isomer. Advantageously, polymerisation catalysts including the metallocene of the invention provide superior olefin polymerisation results.
- -
-
-
- Acid catalysed reaction of indanones, tetralones and benzosuberone with neopentyl glycol and other alkanediols under forced conditions
-
Upon reaction with an excess of 2,2-dimethylpropane-1,3-diol (neopentyl glycol, NPG) under acid catalysis, indanones and tetralones yield indenes and dihydronaphthalenes, respectively. The reaction can also be carried out with butane-1,3-diol.
- Imai, Masao,Morais, Goreti Ribeiro,Al-Hindawi, Bassam,Al-Sulaibi, Mazen A.M.,Meetani, Mohammad,Thiemann, Thies
-
experimental part
p. 325 - 329
(2010/10/19)
-
- A facile method for synthesis of polysubstituted naphthalene derivatives through pyrrolidine catalyzed domino reaction
-
A novel synthetic method for polysubstituted naphthalene derivatives via a pyrrolidine-mediated cascade Michael/Henry reaction was developed, in which easily prepared 2-(2-oxoethyl)benzaldehydes and nitroalkenes were employed as the starting materials. The reaction consists of four consecutive reactions that include a cascade Michael/Henry reaction, a dehydration reaction, and an aromatization reaction in one pot to afford synthetically important naphthalene derivatives with moderate yields.
- Li, Shi-Guang,Hu, Xiu-Qin,Jia, Zhen-Xin,Xu, Peng-Fei
-
supporting information; scheme or table
p. 8557 - 8561
(2010/11/05)
-
- METALLOCENE COMPOUNDS, CATALYSTS COMPRISING THEM, PROCESS FOR PRODUCING AN OLEFIN POLYMER BY USE OF THE CATALYSTS, AND OLEFIN HOMO-AND COPOLYMERS
-
Certain metallocene compounds are provided that, when used as a component in a supported polymerization catalyst under industrially relevant polymerization conditions, afford high molar mass homo polymers or copolymers like polypropylene or propylene/ethylene copolymers without the need for any α-branched substituent in either of the two available 2-positions of the indenyl ligands. The substituent in the 2-position of one indenyl ligand can be any radical comprising hydrogen, methyl, or any other C2-C40 hydrocarbon which is not branched in the α-position, and the substituent in the 2-position of the other indenyl ligand can be any C4-C40 hydrocarbon radical with the proviso that this hydrocarbon radical is branched in the β-position. This metallocene topology affords high melting point, very high molar mass homo polypropylene and very high molar mass propylene-based copolymers. The activity/productivity levels of catalysts including the metallocenes of the present invention are exceptionally high.
- -
-
-
