- "bulky-Yet-Flexible" α-Diimine Palladium-Catalyzed Reductive Heck Cross-Coupling: Highly Anti-Markovnikov-Selective Hydroarylation of Alkene in Air
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To pursue a highly regioselective and efficient reductive Heck reaction, a series of moisture-and air-stable α-diimine palladium precatalysts were rationally designed, readily synthesized, and fully characterized. The relationship between the structures of the palladium complexes and the catalytic properties was investigated. It was revealed that the"bulky-yet-flexible"palladium complexes allowed highly anti-Markovnikov-selective hydroarylation of alkenes with (hetero)aryl bromides under aerobic conditions. Further synthetic application of the present protocol could provide rapid and straightforward access to functional and biologically active molecules.
- Yang, Xu-Wen,Li, Dong-Hui,Song, A-Xiang,Liu, Feng-Shou
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p. 11750 - 11765
(2020/10/23)
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- Chemoselective Hydrogenation of Alkynes to (Z) -Alkenes Using an Air-Stable Base Metal Catalyst
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A highly selective hydrogenation of alkynes using an air-stable and readily available manganese catalyst has been achieved. The reaction proceeds under mild reaction conditions and tolerates various functional groups, resulting in (Z)-alkenes and allylic alcohols in high yields. Mechanistic experiments suggest that the reaction proceeds via a bifunctional activation involving metal-ligand cooperativity.
- Zubar, Viktoriia,Sklyaruk, Jan,Brzozowska, Aleksandra,Rueping, Magnus
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supporting information
p. 5423 - 5428
(2020/07/24)
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- Nickel-Catalyzed C(sp2)?C(sp3) Kumada Cross-Coupling of Aryl Tosylates with Alkyl Grignard Reagents
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Aryl tosylates are an attractive class of electrophiles for cross-coupling reactions due to ease of synthesis, low price, and the employment of C?O electrophiles, however, the reactivity of aryl tosylates is low. Herein, we report the Ni-catalyzed C(sp2)?C(sp3) Kumada cross-coupling of aryl tosylates with primary and secondary alkyl Grignard reagents. The method delivers valuable alkyl arenes by cross-coupling with challenging alkyl organometallics possessing β-hydrogens that are prone to β-hydride elimination and homo-coupling. The reaction is catalyzed by an air- and moisture stable-Ni(II) precatalyst. A broad range of electronically-varied aryl tosylates, including bis-tosylates, underwent this transformation, and many examples are suitable at mild room temperature conditions. The combination of Ar?X cross-coupling with the facile Ar?OH activation/cross-coupling strategy permits for orthogonal cross-coupling with challenging alkyl organometallics. Furthermore, we demonstrate that the method operates with TON reaching 2000, which is one of the highest turnovers observed to date in Ni-catalyzed cross-couplings. (Figure presented.).
- Piontek, Aleksandra,Och?dzan-Siod?ak, Wioletta,Bisz, Elwira,Szostak, Michal
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supporting information
p. 2329 - 2336
(2019/04/13)
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- Cesium carbonate-catalyzed indium insertion into alkyl iodides and their synthetic utilities in cross-coupling reactions
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A catalytic amount of cesium carbonate (10?mol%) was found to be capable of effectively catalyzing the insertion of indium powder into alkyl iodides. The thus-generated alkyl indium reagents could readily undergo palladium-catalyzed cross-coupling reactions with a wide variety of aryl halides, showing compatibility to a range of important functional groups.
- Feng, Xue-Xin,Wu, Zhen,Wang, Qing-Dong,Chen, Bing-Zhi,Rao, Weidong,Yang, Jin-Ming,Shen, Zhi-Liang
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- Preparation of Alkyl Indium Reagents by Iodine-Catalyzed Direct Indium Insertion and Their Applications in Cross-Coupling Reactions
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An efficient method for the synthesis of alkyl indium reagent by means of an iodine-catalyzed direct indium insertion into alkyl iodide in THF is reported. The thus-generated alkyl indium reagents effectively underwent Pd-catalyzed cross-coupling reactions with various aryl halides, exhibiting good compatibility to a variety of sensitive functional groups. By replacing THF with DMA and using 0.75 equiv of iodine, less reactive alkyl bromide could be used as substrate for indium insertion with equal ease.
- Zhi, Man-Ling,Chen, Bing-Zhi,Deng, Wei,Chu, Xue-Qiang,Loh, Teck-Peng,Shen, Zhi-Liang
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p. 3017 - 3023
(2019/02/26)
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- Copper(II)-catalyzed preparation of alkylindium compounds and applications in cross-coupling reactions both in aqueous media
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An efficient water-based method for the synthesis of alkylindium compound in the presence of a catalytic amount of cheap and readily available CuSO4·5H2O (10 mol%) was developed. The thus-generated alkylindium compounds effectively underwent palladium-catalyzed cross-coupling reactions with a myriad of aryl halides in aqueous media, leading to the cross-coupled products in modest to high yields. The mildness of the formed alkyl organometallics allowed the tolerance to various important functional groups incorporated in both substrates of alkyl iodides and aryl halides.
- Wang, Peng,Chen, Bing-Zhi,Guo, Yi-Cong,Rao, Weidong,Shen, Zhi-Liang
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supporting information
(2019/11/11)
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- Cobalt(II)-catalyzed preparation of alkylindium reagents and applications in cross-coupling with aryl halides
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The direct insertion of indium powder into alkyl iodides was found to be efficiently catalyzed by a catalytic amount of cobalt(II) bromide (10 mol%). Upon subjection of the thus-formed alkylindium compounds to palladium-catalyzed cross-coupling reactions with a wide range of aryl halides, a series of cross-coupled products could be obtained in moderate to good yields with the tolerance to many important functional groups.
- Wang, Peng,Song, Xuan-Di,Chen, Bing-Zhi,Rao, Weidong,Shen, Zhi-Liang
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- Application of novel coupling reaction to preparing carbon-carbon bond structured compounds
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The invention relates to application of a novel coupling reaction to preparing carbon-carbon bond structured compounds and mainly provides a reaction between alkyl indium compounds and halides. The reaction between the alkyl indium compounds and the halides can produce corresponding carbon-carbon structured products. The novel coupling reaction is high in process yield, broad in functional group tolerance and good in compatibility.
- -
-
Paragraph 0074-0078
(2019/06/30)
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- Sterically hindered N-heterocyclic carbene/palladium(ii) catalyzed Suzuki-Miyaura coupling of nitrobenzenes
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Palladium-catalyzed denitrative Suzuki coupling of nitroarenes using 2-aryl-5-(2,4,6-triisopropylphenyl)-2,3-imidazolylidene[1,5-a]pyridines as the ligands is described. The key to success is the use of the NHC ligands which show strong donating ability and suitable steric hindrance allowing the successful oxidative addition of Ar-NO2 bonds. Both aromatic and aliphatic boronic acids are tolerated, and a variety of biphenyls and alkylarenes were obtained in good to excellent yields.
- Chen, Kai,Chen, Wei,Yi, Xiaofei,Chen, Wanzhi,Liu, Miaochang,Wu, Huayue
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supporting information
p. 9287 - 9290
(2019/08/08)
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- Ni-Catalyzed Electrochemical Decarboxylative C-C Couplings in Batch and Continuous Flow
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An electrochemically driven, nickel-catalyzed reductive coupling of N-hydroxyphthalimide esters with aryl halides is reported. The reaction proceeds under mild conditions in a divided electrochemical cell and employs a tertiary amine as the reductant. This decarboxylative C(sp3)-C(sp2) bond-forming transformation exhibits excellent substrate generality and functional group compatibility. An operationally simple continuous-flow version of this transformation using a commercial electrochemical flow reactor represents a robust and scalable synthesis of value added coupling process.
- Li, Hui,Breen, Christopher P.,Seo, Hyowon,Jamison, Timothy F.,Fang, Yuan-Qing,Bio, Matthew M.
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p. 1338 - 1341
(2018/03/09)
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- Nickel-Catalyzed Csp2-Csp3 Bond Formation via C-F Bond Activation
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A nickel-catalyzed cross coupling of aryl fluorides via C-F bond activation has been developed. The alkylation method allows selective replacement of aryl fluorides by alkyl groups and enables the synthesis of diverse and otherwise difficult to access scaffolds in good yields.
- Ho, Yee Ann,Leiendecker, Matthias,Liu, Xiangqian,Wang, Chengming,Alandini, Nurtalya,Rueping, Magnus
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supporting information
p. 5644 - 5647
(2018/09/12)
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- A Traceless Tether Strategy for Achieving Formal Intermolecular Hexadehydro-Diels-Alder Reactions
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A synthetic strategy formally equivalent to an intermolecular hexadehydro-Diels-Alder (HDDA) reaction is described. Sulfur-based linkers were designed and constructed by joining terminal alkynes or diynes using alkyne thiolate chemistry. The resulting tetraynes and triynes successfully underwent HDDA cyclization and benzyne trapping. Linker removal by reductive desulfurization was uneventful. The strategy was also found suitable for the tetradehydro-Diels-Alder (TDDA) reaction.
- Smela, Merrick Pierson,Hoye, Thomas R.
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p. 5502 - 5505
(2018/09/12)
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- Cross-coupling of non-activated chloroalkanes with aryl grignard reagents in the presence of iron/N-heterocyclic carbene catalysts
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An efficient and high-yielding cross-coupling reaction of various primary, secondary, and tertiary alkyl chlorides with aryl Grignard reagents was achieved by using catalytic amounts of N-heterocyclic carbene ligands and iron salts. This reaction is a simple and efficient arylation method having applicability to a wide range of industrially abundant chloroalkanes, including polychloroalkanes, which are challenging substrates under conventional cross-coupling conditions.
- Ghorai, Sujit K.,Jin, Masayoshi,Hatakeyama, Takuji,Nakamura, Masaharu
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supporting information; experimental part
p. 1066 - 1069
(2012/04/10)
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- Direct synthesis of water-tolerant alkyl indium reagents and their application in palladium-catalyzed couplings with aryl halides
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A direct result: Alkyl indium reagents are synthesized by the insertion of indium into alkyl halide mediated by CuCl. The synthetic utility of these reagents is demonstrated by their palladium-catalyzed coupling with aryl halides (see scheme). The reagents are compatible with various functional groups, and this makes the protocol generally useful in organic synthesis. DMA=N,N-dimethylacetamide, TBS=tert-butyldimethylsilyl.
- Shen, Zhi-Liang,Goh, Kelvin Kau Kiat,Yang, Yong-Sheng,Lai, Yin-Chang,Wong, Colin Hong An,Cheong, Hao-Lun,Loh, Teck-Peng
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supporting information; experimental part
p. 511 - 514
(2011/03/17)
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- Palladium-catalyzed heck coupling-hydrogenation: Highly efficient one-pot synthesis of dibenzyls and alkyl phenyl esters
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An efficient method for the synthesis of industrially important dibenzyls and alkyl phenyl esters via sequential Heck coupling and hydrogenation of the alkenyl double bond in one pot with a single recyclable catalyst under mild conditions has been realised. The catalyst was recovered by simple filteration and reused for several cycles with consistent activity.
- Kantam, M. Lakshmi,Chakravarti, Rajashree,Chintareddy, Venkat Reddy,Sreedhar,Bhargava, Suresh
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supporting information; experimental part
p. 2544 - 2550
(2009/08/14)
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- Palladium-phosphinous acid-catalyzed cross-coupling of aryl and acyl halides with aryl-, alkyl-, and vinylzinc reagents
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(Chemical Equation Presented) Several palladium-phosphinous acids have been prepared and employed in cross-coupling reactions of aryl or acyl halides with aliphatic and aromatic organozinc reagents. The POPd7-catalyzed reaction of aryl halides, including electron-rich aryl chlorides, and arylzinc reagents was found to afford biaryls exhibiting alkoxy, alkylthio, amino, ketone, cyano, nitro, ester, and heteroaryl groups in 75-93% yield. Excellent results were obtained with sterically hindered substrates which gave di- and tri-ortho-substituted biaryls in up to 92% yield. Aryl halides also undergo POPd7-catalyzed aryl-vinyl and aryl-alkyl bond formation under mild conditions. Styrenes and alkylarenes were prepared in 79-93% yield from aryl halides and vinyl or alkylzinc reagents. The replacement of aryl halides by acyl halides provides access to ketones which were produced in up to 98% yield when POPd was used as catalyst. This approach overcomes the limited substrate scope, reduced regiocontrol, and low functional group tolerance of traditional Friedel-Crafts acylation methods.
- Xu, Hanhui,Ekoue-Kovi, Kekeli,Wolf, Christian
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p. 7638 - 7650
(2008/12/22)
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- Iron-catalyzed desulfinylative C-C cross-coupling reactions of sulfonyl chlorides with grignard reagents
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(Chemical Equation Presented) A friendly couple: Conditions have been uncovered that allow the desulfinylative C-C cross-coupling reaction of inexpensive sulfonyl chlorides and Grignard reagents (see scheme, acac = acetylacetonate, NMP = N-methylpyrrolidone). The reactions rely on environmentally friendly iron catalysts and do not require expensive and/or toxic ligands.
- Rao Volla, Chandra M.,Vogel, Pierre
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p. 1305 - 1307
(2008/12/22)
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- Superior effect of a π-acceptor ligand (phosphine-electron-deficient olefin ligand) in the Negishi coupling involving alkylzinc reagents
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(Chemical Equation Presented) Palladium-catalyzed Negishi cross-coupling involving primary and secondary alkyls, even in the presence of β-H, can be achieved at ambient temperature using chelating ligands containing a phosphine and an electron-deficient olefin. The superior effects of the ligands were shown not only in the desired cross-coupling product yields but also in the fast reaction at mild conditions. This reaction has been also scaled up to 50 g in 0.005 mol % catalyst (20,000 TONs) at room temperature.
- Luo, Xiancai,Zhang, Heng,Duan, Hui,Liu, Qiang,Zhu, Lizheng,Zhang, Tony,Lei, Aiwen
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p. 4571 - 4574
(2008/03/12)
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- Reductive metalation of 1,2-diaryl-substituted ethenes: Synthetic applications
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Reduction of 1,2-diaryl-substituted ethenes with Na metal in dry THF allowed easy access to a variety of 1,2-diaryl-1,2-disodiumethanes. These diorganometallic intermediates were elaborated into the corresponding 1,2-diarylethanes (aqueous work up), or cycloalkylated with 1,3- dichloropropanes. The last reaction led to a highly diastereoselective synthesis of trans-1,2-diaryl-substituted cyclopentanes.
- Azzena, Ugo,Dettori, Giovanna,Lubinu, Caterina,Mannu, Alberto,Pisano, Luisa
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p. 8663 - 8668
(2007/10/03)
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- Cross-coupling reactions of primary alkylboronic acids with aryl triflates and aryl halides
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The cross-coupling reactions of primary alkylboronic acids with aryl triflates and aryl halides has been successfully achieved using PdCl2(dppf)·CH2Cl2 in the presence of potassium carbonate to provide the corresponding Su
- Molander, Gary A.,Yun, Chang-Soo
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p. 1465 - 1470
(2007/10/03)
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- A novel host molecule p-[1-(4-hydroxyphenyl)-1-methylethyl]-calix[8]arene. Synthesis and complexation properties in non-aqueous polar solution
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A novel deep-cavity calixarene, p-[1-(4-hydroxyphenyl)-1-methylethyl]calix[8]arene 1 was synthesized and its complexation with aromatic compounds was examined. Reaction of p-[1-(4-methoxyphenyl)-1-methylethyl]phenol 2 with paraformaldehyde under various conditions only resulted in p-[1-(4-methoxyphenyl)-1-methylethyl]calix[8]arene 3, and no corresponding calix[4]arene and calix[6]arene were detected. Removal of the methyl in the ether groups of 3 afforded 1 in 80% yield. Solubilization, fluorescence and photochemical probe studies demonstrated that 1 forms inclusion complexes with a variety of aromatic compounds in polar non-aqueous solutions.
- Tung, Chen-Ho,Ji, Hai-Feng
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p. 185 - 188
(2007/10/03)
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- MODERN FRIEDEL-CRAFTS CHEMISTRY. XIX THE EFFECT OF REACTION VARIABLES ON PRODUCT DISTRIBUTIONS DURING SOME INTER- AND INTRAMOLECULAR ALKYLATION AND ACYLATIONS OF NAPHTHALENE
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The effect of reaction variables (catalyst, solvebt, time and temperature) on the α, β-orientation during benzylation, benzoylation, β-phenylethylation and phenylacetylation of naphthalene as well as on inter- vs intramolecular reactions of 1-naphthylacetyl chloride and benzene were explored.The identities and quantities of the products were determined by glpc, IR, and NMR using authentically prepared reference samples.The results demonstrated that: (1) In almost all cases, both α- and β-isomers were produced but in different proportions. (2) Complexed AlCl3-CH3NO2 and AlCl3-PhNO2 catalysts favoured β- over α-orientation in reactions of naphthalene and inter- over intramolecular pathway in reactions of 1-naphthylacetyl chloride and benzene. (3) Evidences for reorientation in benzylation and benzoylation of naphthalene and for phenonium ion intermediacy in alkylation with β-phenylethyl bromide are presented.
- Khalaf, Ali Ali,Makki, Mohamed S.I.T.,Kabli, Rida A.
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- Photolysis of the 1-naphthylmethyl ester of substituted phenylacetic acids: intramolecular charge transfer and rates of decarboxylation of arylacyl radicals
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The photolysis of esters 6 and 8 in methanol leads to products resulting from both naphthylmethyl cations and radicals.The product distribution is nearly independent of X for the esters 6 except when X equals methoxy.A mechanism involving initial homolytic cleavage of the carbon-oxygen bond in the excited singlet state of the ester is proposed.Competition between electron transfer in the radical pair to form the ion pair and decarboxylation of the arylacyloxy radical allows calculations of the rates of this decarboxylation process.The ρ values versus ? is close to zero.When X equals methoxy, intramolecular electron transfer occurs with the naphthalene ring serving as the acceptor and the methoxyaromatic as the donor.This exciplex fragments to carbon dioxide and 1-(1-naphthyl)-2-arylethane. Key words: acyloxy radical, decarboxylation, photolysis of benzylic esters.
- Hilborn, James W.,Pincock, James A.
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p. 992 - 999
(2007/10/02)
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- Rates of decarboxylation of acyloxy radicals formed in the photocleavage of substituted 1-naphthylmethyl alkanoates
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Rates of decarboxylation (kCO2R) have been estimated for the acyloxy racicals 7a-f formed in the photolysis of substituted 1-naphthylmethyl 6a-f. These rates are on a mechanism involving initial carbon-oxygen homolytic bond cleavage from the excited singlet state. The products are formed by two competing pathways: electron transfer in the radical pair to give an ion pair and decarboxylation. Measured product yields along with an of the electron-transfer rate (kET) allow calculation of kCO2R as a function of R. The values obtained are the following (R, k (109 s-1)): CH3, 3CH2, 2.0; (CH3)2CH, 6.5; (CH3)3C, 11; PhCH2, 5.0; PhCH2CH2, 2.3.
- Hilborn, James W.,Pincock, James A.
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p. 2683 - 2686
(2007/10/02)
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- Kinetic Isotope Effects as Probes of the Mechanism of Reaction of 1-Naphthylcarbene with Cyclohexane and Toluene
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The rates of reaction of 1-naphthylcarbene (1-NC) in hydrocarbon solution have been measured with excimer laser flash photolysis of 1-naphthyldiazomethane.The kinetic data were obtained by monitoring the growth of the 1-naphthylmethyl radical (1-NCH) at 370 nm.The observed kinetic deuterium isotope effect for the reaction of 1-NC with cyclohexane (cyclohexane-d12) in 2,2,4-trimethylpentane (kH/kD = 1,32 +/- 0.17) and the high CH insertion to H-atom abstraction product ratio are consistent with largely singlet reactivity for 1-NC.In toluene, where addition to the aromatic ring is favored over hydrogen atom abstraction, the measured inverse isotope effect (kH/kD = 0.52 +/- 0.05) also argues for predominantly singlet reactivity and a small singlet-triplet energy gap.The Arrhenius activation parameters measured for the reaction of NC with cyclohexane and toluene were Eact = 2.43 +/- 0.19 kcal/mol, log (A, s-1) = 7.70 +/- 0.15 and Eact = 1.93 +/- 0.38 kcal/mol, log (A, s-1) = 7.28 +/- 0.30, respectively.
- Griffin, G. William,Horn, Keith A.
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p. 4919 - 4926
(2007/10/02)
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- Pd(0)-CATALYZED ELECTRO-REDUCTIVE HYDROCOUPLING OF ARYL HALIDES WITH OLEFINS AND ACETYLENES
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Electro-reductive hydrocoupling of aryl halides with olefins and acetylenes has been performed in an Et4NOTs-DMF-(Pb cathode) system in the presence of catalytic amounts of PdCl2(Ph3P)2.
- Torii, Sigeru,Tanaka, Hideo,Morisaki, Kazuo
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p. 1353 - 1354
(2007/10/02)
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- Photoextrusion of SO2 from Arylmethyl Sulfones: Exploration of the Mechanism by Chemical Trapping, Chiral, and CIDNP Probes
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The photochemistry of eight benzylic sulfones, all of which efficiently extrude sulfur dioxide, was studied by a variety of methods.Optically active sulfones (S)-(-)-8, (S)-(-)-11, (S)-(-)-12, (S)-(+)-13, and (R)-(+)-14 were employed to measure the extent of the "hidden" return of the initial photogenerated intermediates by the stereoequilibration of the chiral center.By comparison of the regioisomeric methyl sulfones 11 vs. 13 and 12 vs. 14, preferential C-S bond fragmentation on the naphthyl side was established for the singlet excited sulfones.Added nucleophilic and proton trapping agents had no effect on the course of the reaction, ruling out ionic intermediates.The three hydrocarbon products of photodesulfonation from the unsymmetrical sulfones 8-14 provided a measure of the cage effects, which were highly structure and multiplicity dependent.Rate constants for reaction, and fluorescence, as well as the energy transfer rates from benzophenone were determined.The reaction rate constant for singlet reactivity from the 1-naphthyl sulfones was about three times greater than that for the 2-naphthyl derivatives.CIDNP studies showed a strong product signal for the 1-naphthyl sulfones from desulfonation of a triplet caged radical pair.Naphthaldehyde formation, a very minor, triplet process, was also detected by the CIDNP study of sulfones 9-12.
- Givens, Richard S.,Hrinczenko, Borys,Liu, Jerry H.-S.,Matuszewski, Bogdan,Tholen-Collison, Joan
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p. 1779 - 1789
(2007/10/02)
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- MECHANISTIC STUDIES OF THE PHOTODECOMPOSITION OF ARYLMETHYL SULFONES IN HOMOGENEOUS AND MICELLAR SOLUTIONS.
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The mechanism of photodecomposition of aryl sulfones has been investigated by using both steady-state and time-resolved techniques. Direct evidence for radical and triplet-state intermediates is provided. A correlation is found between the dynamics of reaction of the intermediate triplet states with the stabilities of the intermediate radicals.
- Gould,Tung,Turro,Givens,Matuszewski
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p. 1789 - 1793
(2007/10/02)
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- The mechanism of the photo-induced homolysis of aryl halides
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Irradiation of the ω-(4-halophenoxy)alkyl bromides (Ia,b n=10) in methanol usually leads to preferential cleavage of the aryl-halogen bond and data is presented supporting the conclusion that this occurs from the first excited single state.
- Davidson, R.Stephen,Goodin, Jonathan W.,Kemp, Graham
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p. 2911 - 2914
(2007/10/02)
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