- Synthesis and Reaction of Anthracene-Containing Polypropylene: A Promising Strategy for Facile, Efficient Functionalization of Isotactic Polypropylene
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A novel anthracene-containing isotactic polypropylene (An-iPP) with high molecular weight (>10 × 104) and satisfying incorporation (5.7 mol %) was synthesized via direct copolymerization of propylene and 9-hexenylanthracene. The pendent anthryl group of the resulting An-iPP is quite active, and this provides a facile and efficient avenue to synthesize various functional iPPs. As a typical and important example, maleic anhydride (MA) functionalized polypropylene, was successfully prepared in a highly efficient, catalyst-free, byproduct-free, and controllable way via mild Diels-Alder (D-A) reaction between pendent anthryl groups and MA. More importantly, the D-A functionalization process did not sacrifice the original properties of the An-iPP, as no unfavorable degradation and cross-linking were detected in DSC and GPC analyses. Besides MA, several other dienophiles could also be conveniently used as functional reagents to prepare various functionalized iPPs with distinct properties. The unique fluorescent property of An-iPP was studied and could be used for functionalization process monitoring.
- Zhang, Deguang,Pan, Li,Li, Yanguo,Wang, Bin,Li, Yuesheng
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- Functionalization of Alkenyl C-H Bonds with D 2 O via Pd(0)/Carboxylic Acid Catalysis
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We report herein a simple catalytic method for the extensive labeling of alkenyl C-H bonds through the combination of a palladium(0) complex and a carboxylic acid in the presence of deuterium oxide. The reaction can be applied to a variety of terminal alkenes and the best results are obtained with aryl-substituted examples. This method represents a convenient approach for the preparation of extensively labeled chemicals from the cheapest and safest source of deuterium.
- Bigi, Franca,Camedda, Nicola,Cera, Gianpiero,Maestri, Giovanni,Maggi, Raimondo,Serafino, Andrea
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supporting information
p. 1762 - 1772
(2020/06/08)
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- Copper-Catalyzed Defluorinative Hydroarylation of Alkenes with Polyfluoroarenes
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A catalytic defluorinative hydroarylation of alkenes with polyfluoroarenes in the presence of dppbz-ligated Cu catalyst and silanes was developed. This method provides a straightforward and alternative avenue to synthetic important polyfluorinated arenes with readily available and bench-stable alkenes as latent nucleophiles, and therefore avoids conventional reliance on stoichiometric quantities of organometallic reagents. This reaction proceeds under very mild conditions and exhibits good functional group compatibility and high level of regioselectivity. The synthetic potential of this method was further demonstrated by a gram-scale synthesis, and an array of experimental studies were also carried out to elaborate the probable mechanism.
- Fu, Bin,Li, Xiaohong,Xiong, Tao,Yuan, Xiuping,Zhang, Qian,Zhang, Qiao
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supporting information
p. 23056 - 23060
(2020/10/19)
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- Photoinduced, copper-catalyzed three components cyanofluoroalkylation of alkenes with fluoroalkyl iodides as fluoroalkylation reagents
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In the past few years, Ru and Ir catalyzed photoredox radical coupling reactions have been widely applied in organic synthesis. In contrast, the applications of Cu catalysts in photoredox organic transformations were limited. We here report the first example of photoinduced, Cu-catalyzed three component cyanofluoroalkylation of alkenes by directly using fluoroalkyl iodides as fluoroalkylation reagents.
- Guo, Quanping,Wang, Mengran,Wang, Yanfang,Xu, Zhaoqing,Wang, Rui
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supporting information
p. 12317 - 12320
(2017/11/20)
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- Hantzsch Ester as a Photosensitizer for the Visible-Light-Induced Debromination of Vicinal Dibromo Compounds
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The debromination of vicinal dibromo compounds to generate alkenes usually requires harsh reaction conditions and the addition of catalysts. Just recently the visible-light-induced debromination of vicinal dibromo compounds emerged as a possible alternative to commonly used methods, but the substrate scope of this reaction is limited and a photocatalyst is necessary for the successful conversion of the starting compounds. A catalyst-free visible-light-induced debromination of vicinal dibromo compounds with a base-activated Hantzsch ester as photosensitizer is reported. The method has a wide substrate scope and a broad functional-group compatibility.
- Chen, Wenxin,Tao, Huachen,Huang, Wenhao,Wang, Guoqiang,Li, Shuhua,Cheng, Xu,Li, Guigen
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supporting information
p. 9546 - 9550
(2016/07/14)
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- Synthesis and photochemical transformations of a few olefin-appended 11,12-dibenzoyldibenzobarrelenes
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Several olefin-appended dibenzobarrelenes have been synthesised by Diels-Alder reaction between 9-alkenylanthracenes and dibenzoylacetylene under carefully controlled conditions and their photochemistry was examined. Olefin appendages acted as efficient quenchers of the triplet state of these barrelenes.
- Jacob, Ambily Mary,George, Gisha,Jacob, Jomon P.,Mathew, Eason M.
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p. 199 - 202
(2015/06/02)
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- Catalytic wittig reactions of semi- and nonstabilized ylides enabled by ylide tuning
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The first examples of catalytic Wittig reactions with semistabilized and nonstabilized ylides are reported. These reactions were enabled by utilization of a masked base, sodium tert-butyl carbonate, and/or ylide tuning. The acidity of the ylide-forming proton was tuned by varying the electron density at the phosphorus center in the precatalyst, thus facilitating the use of relatively mild bases. Steric modification of the precatalyst structure resulted in significant enhancement of E selectivity up to >95:5, E/Z. Time for a tune up: Catalytic Wittig reactions with semi- and nonstabilized ylides were enabled by use of a masked base (NaOCO2tBu) and/or ylide tuning. The acidity of the ylide-forming proton was tuned by varying the electron density at the P center in the precatalyst, thus facilitating the use of relatively mild bases. Steric modification of the precatalyst structure resulted in significant enhancement of E selectivity.
- Coyle, Emma E.,Doonan, Bryan J.,Holohan, Andrew J.,Walsh, Killian A.,Lavigne, Florie,Krenske, Elizabeth H.,O'Brien, Christopher J.
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supporting information
p. 12907 - 12911
(2016/02/18)
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- METHODS FOR PHOSPHINE OXIDE REDUCTION IN CATALYTIC WITTIG REACTIONS
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A method for increasing the rate of phosphine oxide reduction, preferably during a Wittig reaction comprising use of an acid additive is provided. A room temperature catalytic Wittig reaction (CWR) the rate of reduction of the phosphine oxide is increased due to the addition of the acid additive is described. Furthermore, the extension of the CWR to semi-stabilized and non-stabilized ylides has been accomplished by utilization of a masked base and/or ylide-tuning.
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Page/Page column 59; 68; 69; 70
(2014/09/29)
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- Evaluating the use of chiral anthracene templates to access pyroglutamic acids
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An approach for the asymmetric synthesis of pyroglutamic acid derivatives is described based on an anthracene chiral auxiliary. The introduction of a furan ring as a masked carboxylic acid moiety proceeded with excellent levels of diastereo-selectivity, followed by conversion into a carboxylate ester. The ensuing retro-Diels-Alder procedure using flash vacuum pyrolysis (FVP) followed by reduction gave pyroglutamate esters in good yield but poor enantioselectivity, the latter of which was found to be dependant on the electronic nature of the N-protecting group.
- Hasbullah, Siti Aishah,Jones, Simon
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experimental part
p. 2719 - 2725
(2011/02/16)
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- Removal, recovery, and recycling of triarylphosphonium-supported tin reagents for various organic transformations
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Phosphonium-supported tin reagents and catalysts were prepared and were shown to be effective in Stille couplings, radical dehalogenations, radical cyclizations, and carbonyl allylations. Not only could the tin residues be removed from the crude reaction mixture through a phase separation process but also they could be recovered and recycled.
- Poupon, Jean-Christophe,Marcoux, David,Cloarec, Jean-Manuel,Charette, Andre B.
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p. 3591 - 3594
(2008/02/12)
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- Significant enhancement of the Stille reaction with a new combination of reagents-copper(I) iodide with cesium fluoride
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A systematic investigation for enhancement of Stille reaction using the combination of copper(I) iodide and cesium fluoride was described. Initial route to the target compound involved a double Stille coupling in the carbon-carbon bond formation of the key intermediate 1. Homocoupling has often been observed in this reaction especially when electron-withdrawing substituents are present in conjugation with tin. After extensive optimization, a variety of electronically unfavourable and sterically hindered substrates were coupled in very high yields under mild conditions.
- Mee, Simon P. H.,Lee, Victor,Baldwin, Jack E.
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p. 3294 - 3308
(2007/10/03)
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- Selective synthesis of (E)-triethyl(2-arylethenyl)silane derivatives by reaction of aryl bromides with triethyl vinylsilane catalysed by a palladium-tetraphosphine complex
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Cis, cis, cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane / 0.5 [PdCl(C3H5)]2 system catalyses the Heck reaction of vinylsilane derivatives with a range of aryl bromides with high ratio substrate/catalyst in good yields. The formation of mixtures of styrene, (E)-triethyl(2-arylethenyl)silane and triethyl(1-arylethenyl)silane derivatives was observed in some cases. Very high selectivities (up to 100%) in favour of the formation of (E)-triethyl(2-arylethenyl)silane derivatives were obtained in the presence of sodium acetate as base. With other bases such as potassium carbonate, the formation of large amounts of styrene derivatives was observed. The reaction tolerates several functions such as fluoro, trifluoromethyl, methoxy, dimethylamino, acetyl, formyl, benzoyl, carboxylate, nitro or nitrile. Moreover, turnover numbers up to 10,000 can be obtained for this reaction.
- Battace, Ahmed,Zair, Touriya,Doucet, Henri,Santelli, Maurice
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p. 3790 - 3802
(2007/10/03)
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- Stille coupling made easier - The synergic effect of copper(I) salts and the fluoride ion
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CsF and Cul do the trick: Stille coupling reactions of aryl/vinyl iodides, triflates, and bromides with aryl/vinyl stannanes are greatly enhanced by the inclusion of CsF and Cul in the reaction mixture (see scheme; Conditions A: [Pd(PPh3)4]/CsF/ Cul/DW/45 °C; Conditions B: PdCl 2/ PtBu3/CsF/Cul/DMF/45 °C).
- Mee, Simon P. H.,Lee, Victor,Baldwin, Jack E.
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p. 1132 - 1136
(2007/10/03)
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- Pd/P(t-Bu)3: A mild and general catalyst for stille reactions of aryl chlorides and aryl bromides
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Pd/P(t-Bu)3 serves as an unusually reactive catalyst for Stille reactions of aryl chlorides and bromides, providing solutions to a number of long-standing challenges. An unprecedented array of aryl chlorides can be cross-coupled with a range of organotin reagents, including SnBu4. Very hindered biaryls (e.g., tetra-ortho-substituted) can be synthesized, and aryl chlorides can be coupled in the presence of aryl triflates. The method is user-friendly, since a commercially available complex, Pd(P(t-Bu)3)2, is effective. Pd/P(t-Bu)3 also functions as an active catalyst for Stille reactions of aryl bromides, furnishing the first general method for room-temperature cross-couplings.
- Littke, Adam F.,Schwarz, Lothar,Fu, Gregory C.
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p. 6343 - 6348
(2007/10/03)
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- Characterization of the combustion products of polyethylene
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Polyethylene (PE) was burned in a tube-type furnace with an air flow at a temperature of 600~900°C. Combustion products were collected with glass wool, glass fiber filter, and XAD-2 adsorbent. The analysis of the products was performed with GC-FID and GC-MSD. At low temperature, hydrocarbons were the major components, while at higher temperature the products were composed of polycyclic aromatic hydrocarbons. With the high performance of the Hewlett-Packard 6890GC-5973MSD, more compounds were identified in comparison with previous studies.
- Piao, Mingjun,Chu, Shaogang,Zheng, Minghui,Xu, Xiaobai
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p. 1497 - 1512
(2007/10/03)
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- Design of new modifiers for the enantioselective hydrogenation of ethyl pyruvate
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All efficient chiral modifiers for Pt in the enantioselective hydrogenation of α-ketoesters possess a basic, secondary or tertiary N atom for interacting with the carbonyl group of the reactant and an aromatic ring system for adsorptive anchoring of the activated complex on Pt. Analysis of the available data suggested that an enlargement of the naphthalene or quinoline anchoring moiety should improve the enantioselection. Accordingly, 1-(9-anthracenyl)-2-(1-pyrrolidinyl)ethanol (10) has been synthesized and tested in the hydrogenation of ethyl pyruvate. The best enantiomeric excess achieved with the new modifier was 87%, which is 12% higher than the optimized value obtained with the corresponding naphthalene derivative (4). A further advantage of the new modifier is the higher stability against self-hydrogenation. Hydrogenation of ethyl pyruvate in the presence of modifier mixtures indicated the following order of adsorption strength on Pt: cinchonidine > 10 > 4. This ranking correlates with the best enantiomeric excesses obtained with these modifiers. Compared with the other modifiers, the number of possible conformations for 10 is reduced because of the symmetry of the anthracenyl ring system. Molecular mechanics calculations suggest that the energy and geometry of the transition complexes between ethyl pyruvate and 10 or 4 are similar. Accordingly, the better efficiency of 10 should be due to its stronger adsorption on Pt and higher acceleration of the modified reaction compared with the competing nonenantioselective (unmodified) reaction. Substituting the 9-anthracenyl group of 10 with a 9-triptycenyl moiety led to a complete loss of enantiodifferentiation, demonstrating that the extended flat aromatic ring system is a crucial structural element of efficient modifiers for α-ketoester hydrogenation.
- Schuerch, Markus,Heinz, Thomas,Aeschimann, Roland,Mallat, Tamas,Pfaltz, Andreas,Baiker, Alfons
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p. 187 - 195
(2007/10/03)
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- Palladium-Catalyzed Substitution of Esters of Naphthylmethanols, 1-Naphthylethanols, and Analogues by Sodium Dimethyl Malonate. Stereoselective Synthesis from Enantiomerically Pure Sbstrates.
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The palladium-catalyzed substitution of carbonates of the titled alcohols was performed at lower temperature than the previously reported reaction of the corresponding acetates.The use of enantiomerically pure carbonates gave substitution products with overall retention of the configuration (up to 97 percent).
- Legros, Jean-Yves,Toffano, Martial,Fiaud, Jean-Claude
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p. 3235 - 3246
(2007/10/02)
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- 1H and 13C Nuclear Magnetic Resonance Studies of Ethenyl-Substituted Benzenoid Aromatic Compounds
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1H and 13C NMR studies were carried out on 1-ethenylnaphthalene, 2-ethenylnaphthalene, 9-ethenylanthracene, 9-ethenylphenanthrene, 1-ethenylpyrene and 1-ethenylperylene.Assignments of proton and carbon resonances were made with the aid of 2D COSY, 2D COLOC, 2D COLOCS, 3J(H,C) INAPT, and NOE difference spectral techniques.
- Katritzky, Alan R.,Hitchings, Gregory J.,King, Roy W.,Zhu, Dong W.
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- Nickel-Catalyzed Olefination of Cyclic Benzylic Dithioacetals by Grignard Reagents. Scope and Mechanism
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The details of the first nickel-catalyzed olefination of cyclic dithioacetals to form substituted styrenes and aryl-substituted 1,4-pentadienes are described.The reaction represents a new synthetic use of the dithioacetal functionality.Only nickel complexes catalyzes these cross-coupling reactions; palladium complexes displayed no catalytic activity under the reaction conditions employed.Selective coupling occurred.A mechanism for the reaction is proposed.The experimental evidence indicates that, in these nickel-catalyzed couplings, cyclic dithioacetals are more reactive than their acyclic analogues.This increased reactivity appears to be the result of maintaining the two sulfur atoms in close proximity to each other by the use of a short chain of methylene groups.
- Ni, Zhi-Jie,Mei, Nai-Wen,Shi, Xian,Tzeng, Yih-Ling,Wang, Maw Cherng,Luh, Tien-Yau
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p. 4035 - 4042
(2007/10/02)
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- An esr study of aromatic olefin radical cations
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γ-Irradiation of phenyl-and diphenylethenes in CFCl3 matrix at 77 K resulted in the formation of the substrate radical cations. 1,1-Diphenyl-2-methylpropene radical cations exhibit a spin density (ρ=0.45) at the β carbon much higher than those of stilbene and 2-styrylnaphthalene radical cations and comparable to those of styrene and α-methylstyrene radical cations. The spin density at the vinyl carbons appears to play an important role in governing the reactivity of the olefin radical cations with molecular oxygen.
- Bonazzola,Michaut,Roncin,Misawa,Sakuragi,Tokumaru
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p. 347 - 352
(2007/10/02)
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- Kinetics vs Thermodynamic Factors in α-Hydrogen Atom Abstraction from Alkyl Aromatics
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The relative reactivities of several 9-alkylanthracenes toward bromine atom have been determined.Whereas for alkylbenzenes it is observed that isopropyl > ethyl > methyl, an inverted reactivity order was observed in the 9-anthryl system: methyl (1.00) > cyclopropyl (0.33) > ethyl (0.063) >> isopropyl ( 0.001), per α-hydrogen at 80 deg C.Stereoelectronic factors, specifically the alignment of the α-C-H bond with the anthryl ?-system, are implicated as bearing primary responsibility for this unusual reactivity order.In a general context, the relative importance of stereoelectronic effects vs the stability of the incipient radical in hydrogen atom abstraction from alkyl aromatics is discussed.
- Tanko, James M.,Mas, Rosemal H.
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p. 5145 - 5150
(2007/10/02)
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- On the Neophyl-like Rearrangement of 2-(9-Anthryl)ethyl Radicals
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The 1,2 migration of the aryl group in deuterated 2-(9-anthryl)ethyl and 2-ethyl radicals has been studied by product analyses with the use of the competing reaction ArCH2CD2(.) + Bu3SnH.The rearrangement was so fast that equimolecular mixtures of the unrearranged (ArCH2CD2H) and rearranged (ArCD2CH3) hydrocarbons were obtained even in the presence of a large excess of Bu3SnH (ca. 1 M).The lower limit for the rate constant of the intramolecular process, kr, could be estimated as 5E7 s-1.Ab initio MO computations, performed on the2-phenylethyl radical, chosen as the simplest model for 2-arylethyls, showed that the aryl migration may occur either through the intermediacy of the spirocyclopropanecyclohexadienyl radical or via a three-membered transition state having geometrical and electronic properties different from those of the potential cyclic intermediate.The spectroscopic and chemical results are consistent with the rearrangement taking place via the intermediacy of spirocyclopropane radicals, which, as both thermochemical calculations and experimental evidence indicate, are characterized by a considerable thermodynamic stability.In fact, the spiro radicals could be easily observed by EPR spectroscopy when generated by hydrogen abstraction from the corresponding cyclic hydrocarbons, and the kinetics of their decay could be studied.The diamagnetic dimer of the 9,10-dihydro-10-spiro-9-yl radical was also isolated, and its structure determined by X-ray crystallographic analysis.The same cyclized radicals were detected when producing the two arylethyl radicals within the EPR cavity.Chemical generation of the 2-(9-anthryl)ethyl radical in the presence of low concentrations of hydrogen donors led to the isolation of remarkable amounts of the dimer of its cyclic structural isomer.These results provide evidence that the 2-anthrylethyl radical and the phenyl-substituted analogue may exist in either of the two rapidly equilibrating open-chain and cyclized forms and react preferentially in one of them depending on the experimental conditions.
- Leardini, Rino,Nanni, Daniele,Pedulli, Gian Franco,Tundo, Antonio,Zanardi, Giuseppe,et al.
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p. 7723 - 7732
(2007/10/02)
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- Reactions of the 1,8-Diphenylanthracene System
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An improved synthesis of 1,8-diphenylanthracene (1) is described along with various reactions of this hydrocarbon, including electrophilic substitution reactions, oxidations, and addition of n-BuLi.The molecular geometry of a derivative, 10-bromo-1,8-diphenylanthracene (20), was determined by X-ray crystallography.Of the various routes explored for forming 9-substituted 1,8-diphenylanthracenes, only the addition of certain organometallic reagents to the 9-anthrone 10 was satisfactory.
- House, Herbert O.,Ghali, Nabih I.,Haack, John L.,VanDerveer, Don
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p. 1807 - 1817
(2007/10/02)
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