- Photochemical reactions of di(naphthyl-1-methyl)mercury in various solvents
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It was found that the photolysis of di(naphthyl-1-methyl)mercury (1) gives 1,2-dinaphthylethane (2) in heptane and benzene solvents and 2 and 1-methylnaphthalene in isopropanol and acetonitrile. Irradiation of 1 in carbon tetrachloride gives 2 and ClHgCH2C10H7 as primary reaction products, while the chloride is further photolyzed to 2. Quantum yields of the photolysis of 1 are high and equal to unity almost for all solvents. The chloride photodecomposition yield is an order of magnitude lower (0.1).
- Ivanov,Roznyatovskii,Ustynyuk,Buchachenko
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- Reaction of Benzyl and Naphthylmethyl Esters with Arene Radical Anions
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The reactions of four esters, naphth-1-ylmethyl acetate, naphth-1-ylmethyl benzoate, benzyl acetate, and benzyl benzoate, with the salts of radical anions of fluoranthene and biphenyl have been studied.When ester radical anion formation is energetically possible, CH2-O bond cleavage follows rapidly.The resultant ArCH2 radical is reduced under the reaction conditions.The ArCH2 anion thus produced can react with the ester both as a nucleophile and as a base to promote a variety of side reactions.In most cases, these processes compete with the initial reduction and cleavage.
- Shi, Buchang,Guthrie, Robert D.
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- Photochemistry of Naphthylmethyl Halides. Direct and Sensitized Paths to Homolytic and Heterolytic Carbon-Halogen Bond Cleavage
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Photolysis of the 1-(halomethyl)naphthalenes (X=Cl, Br, I) in methanol and in cyclohexane solution was investigated.Direct and sensitized irradiation leads to carbon-halogen bond cleavage.In methanol solution direct irradiation leads to products of carbon-halogen bond heterolysis, i.e. (methoxymethyl)naphthalene, as well as products derived from bond homolysis.In cyclohexane only homolysis products are observed.The mechanism of the photoreactions was probed by laser spectroscopy, sensitization, and quenching techniques.The results indicate that bond cleavage occurs from excited singlet states but not from the lowest triplet state.Also, an exciplex between sensitizers and the (halomethyl)naphthalene also undergoes carbon-halogen bond cleavage.
- Slocum, Gregory H.,Schuster, Gary B.
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- One- and Two-Photon Processes in the Photochemistry of 1,3-Bis(1-naphthyl)-2-propanone: An Example of a "Reluctant" Norrish Type I Reaction
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Photoexcitation of 1,3-bis(1-napthyl)-2-propanone in the carbonyl or naphthalene chromophore leads to the formation of a carbonyl-localized singlet state in the subnanosecond time scale.This singlet decays (τs = 1.4 ns in isooctane), presumably to yield the carbonyl triplet, which rapidly populates the naphthalene-localized triplet state.This intermediate can be readily detected by laser flash photolysis and shows typical naphthalene-like characteristics (TT absorption, λmax = 430 nm).Product and quenching studies indicate that the Norrish type I clevage occurs from the singlet state with Φ ca. 0.002.Excitation of the triplet state with the pulses from a dye laser (430 nm) leads to cleavage of the CH2-CO bond to yield 1-naphthylmethyl radicals in a process that we describe as a "reluctan" Norrish Type I reaction.The quantum yield for this process is ca.0.06.The structural features required for this type of process to occur are discussed.
- Johnston, Linda J.,Scaiano, J. C.
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- Mixed Alkyl/Aryl Diphos Ligands for Iron-Catalyzed Negishi and Kumada Cross Coupling Towards the Synthesis of Diarylmethane
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Mixed alkyl/aryl diphos ligands have been prepared and their application in iron-catalyzed cross coupling of benzylic chlorides with diaryl zinc (Negishi) or aryl Grignard reagents (Kumada) towards the synthesis of diarylmethane has been evaluated. The iron?diphos catalytic system exhibited the enhanced activity and selectivity in the two coupling reactions. The electron-rich mixed PPh2/PCy2 ligands outperformed their symmetrical PPh2 congeners, and led to decreased homocoupling byproduct formation. It indicates that the electronic effect of the ligands plays an important role in the catalytic performance. The Fe catalyst supported by L8 bearing an electron-rich PCy2 substituent and a sterically demanding tert-butyl on ethene backbone exhibited the best catalytic performance and good functional group tolerance in the two cross coupling reactions.
- Ma, Xufeng,Wang, Han,Liu, Yao,Zhao, Xing,Zhang, Jun
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p. 5134 - 5140
(2021/11/16)
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- Ni-Catalyzed Iterative Alkyl Transfer from Nitrogen Enabled by the in Situ Methylation of Tertiary Amines
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Current methods to achieve transition-metal-catalyzed alkyl carbon-nitrogen (C-N) bond cleavage require the preformation of ammonium, pyridinium, or sulfonamide derivatives from the corresponding alkyl amines. These activated substrates permit C-N bond cleavage, and their resultant intermediates can be intercepted to affect carbon-carbon bond-forming transforms. Here, we report the combination of in situ amine methylation and Ni-catalyzed benzalkyl C-N bond cleavage under reductive conditions. This method permits iterative alkyl group transfer from tertiary amines and demonstrates a deaminative strategy for the construction of Csp3-Csp3 bonds. We demonstrate PO(OMe)3 (trimethylphosphate) to be a Ni-compatible methylation reagent for the in situ conversion of trialkyl amines into tetraalkylammonium salts. Single, double, and triple benzalkyl group transfers can all be achieved from the appropriately substituted tertiary amines. Transformations developed herein proceed via recurring events: The in situ methylation of tertiary amines by PO(OMe)3, Ni-catalyzed C-N bond cleavage, and concurrent Csp3-Csp3 bond formation.
- Nwachukwu, Chideraa Iheanyi,McFadden, Timothy Patrick,Roberts, Andrew George
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p. 9979 - 9992
(2020/09/03)
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- A clean and selective radical homocoupling employing carboxylic acids with titania photoredox catalysis
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A titania photoredox catalysis protocol was developed for the homocoupling of C-centered radicals derived from carboxylic acids. Intermolecular reactions were generally efficient and selective, furnishing the desired dimers in good yields under mild neutral conditions. Selective cross-coupling with two acids proved unsuccessful. An intra-molecular adaptation enabled macrocycles to be prepared, albeit in modest yields. (Chemical Equation Presented).
- Manley, David W.,Walton, John C.
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supporting information
p. 5394 - 5397
(2015/02/19)
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- Ultrasound-promoted dimerization of benzylic halides
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Simple and straightforward coupling of benzylic compounds was achieved by sonicating benzylic halides in the presence of magnesium.
- Gozhina, Olga V.,Thomassen, Ivar K.,Lejon, Tore
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p. 1867 - 1870
(2013/05/21)
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- Facile reductive coupling of benzylic halides with ferrous oxalate dihydrate
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Facile reductive coupling of benzylic halides is reported with ferrous oxalate dihydrate in DMF or HMPA under nitrogen atmosphere at 155-160°C. The coupling is proposed to proceed by two successive oxidative additions of benzylic halides to ferrous oxalate to give an intermediate organoiron complex which undergoes concerted dimerization to give the corresponding reductively coupled dimers in high yields.
- Khurana, Jitender M.,Chauhan, Sushma,Maikap, Golak C.
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p. 1737 - 1740
(2007/10/03)
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- Mechanistic investigation of a novel vitamin B12-catalyzed carbon-carbon bond forming reaction, the reductive dimerization of arylalkenes
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In the presence of catalytic vitamin B12 and a reducing agent such as Ti(III)citrate or Zn, arylalkenes are dimerized with unusual regioselectivity forming a carbon-carbon bond between the benzylic carbons of each coupling partner. Dimerization products were obtained in good to excellent yields for mono- and 1,1-disubstituted alkenes. Dienes containing one aryl alkene underwent intramolecular cyclization in good yields. However, 1,2-disubstituted and trisubstituted alkenes were unreactive. Mechanistic investigations using radical traps suggest the involvement of benzylic radicals, and the lack of diastereoselectivity in the product distribution is consistent with dimerization of two such reactive intermediates. A strong reducing agent is required for the reaction and fulfills two roles. It returns the Co(II) form of the catalyst generated after the reaction to the active Co(I) state, and by removing Co(II) it also prevents the nonproductive recombination of alkyl radicals with cob(II)alamin. The mechanism of the formation of benzylic radicals from arylalkenes and cob(I)alamin poses an interesting problem. The results with a one-electron transfer probe indicate that radical generation is not likely to involve an electron transfer. Several alternative mechanisms are discussed.
- Shey, Justin,McGinley, Chris M.,McCauley, Kevin M.,Dearth, Anthony S.,Young, Brian T.,Van der Donk, Wilfred A.
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p. 837 - 846
(2007/10/03)
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- Flash vacuum pyrolysis over magnesium. Part 1 - Pyrolysis of benzylic, other aryl/alkyl and aliphatic halides
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Flash vacuum pyrolysis over a bed of freshly sublimed magnesium on glass wool results in efficient coupling of benzyl halides to give the corresponding bibenzyls. Where an ortho halogen substituent is present further dehalogenation gives some dihydroanthracene and anthracene. Efficient coupling is also observed for halomethylnaphthalenes and halodiphenylmethanes while chlorotriphenylmethane gives 4,4′-bis(diphenylmethyl)biphenyl. By using α,α′-dihalo-o-xylenes, benzocyclobutenes are obtained in good yield, while the isomeric α,α′-dihalo-p-xylenes give a range of high thermal stability polymers by polymerisation of the initially formed p-xylylenes. Other haloalkylbenzenes undergo largely dehydrohalogenation where this is possible, in some cases resulting in cyclisation. Deoxygenation is also observed with haloalkyl phenyl ketones to give phenylalkynes as well as other products. With simple alkyl halides there is efficient elimination of HCl or HBr to give alkenes. For aliphatic dihalides this also occurs to give dienes but there is also cyclisation to give cycloalkanes and dehalogenation with hydrogen atom transfer to give alkenes in some cases. For 5-bromopent-1-ene the products are those expected from a radical pathway but for 6-bromohex-1-ene they are clearly not. For 2,2-dichloropropane and 1,1-dichloropropane elimination of HCl occurs but for 1,1-dichlorobutane, -pentane and -hexane partial hydrolysis followed by elimination of HCl gives E, E-, E,Z- and Z,Z- isomers of the dialk-1-enyl ethers and fully assigned 13C NMR data are presented for these. With 6-chlorohex-1-yne and 7-chlorohept-1-yne there is cyclisation to give methylenecycloalkanes and -cycloalkynes. The behaviour of 1,2-dibromocyclohexane and 1,2-dichlorocyclooctane under these conditions is also examined. Various pieces of evidence are presented that suggest that these processes do not involve generation of free gas-phase radicals but rather surface-adsorbed organometallic species.
- Aitken, R. Alan,Hodgson, Philip K.G.,Morrison, John J.,Oyewale, Adebayo O.
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p. 402 - 415
(2007/10/03)
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- Fragmentation of anion radicals with elimination of aryloxy groups
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4-Vinylbenzyl phenyl ether, 4-phenylbenzyl phenyl ether, 1- and 2-naphthylmethyl phenyl ethers react with sodium thiophenolate under photochemical stimulation with replacement of the phenoxy group. The composition of reaction products and relation of reactivity to the structure of substrates is consistent with anion-radical mechanism. The corresponding methoxy and cyano derivatives do not undergo the reaction.
- Dneprovskii,Fedosov
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p. 1438 - 1443
(2007/10/03)
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- Silver catalyzed zinc Barbier reaction of benzylic halides in water
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Benzylic chlorides react in aqueous dibasic potassium phosphate under silver catalysis with aromatic aldehydes in the presence of zinc dust to give 1,2-diaryl alcohols in moderate to good yields. Dimerization to bibenzyls and reduction of the halide are important side reactions. A wide range of substituted aromatic and heteroaromatic aldehydes and of substituted benzylic chlorides can be used. Aliphatic aldehydes and ketones are unreactive. A mechanism of two SET on the metal surface is discussed.
- Bieber, Lothar W.,Storch, Elisabeth C.,Malvestiti, Ivani,Da Silva, Margarete F.
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p. 9393 - 9396
(2007/10/03)
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- Stoichiometrically sensitized decarboxylation occurring in the two-component molecular crystals of aza aromatic compounds and aralkyl carboxylic acids
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Highly selective photodecarboxylation could be achieved by utilizing a series of two-component molecular crystals of aralkyl carboxylic acids such as 3-indolepropionic acid (a) and 1-naphthylacetic acid (b) combined with acridine (1) or phenanthridine (2) as an electron acceptor. The 1:1 hydrogen bonded crystals were prepared by recrystallization from the solutions. Irradiation of the crystals at -70°C caused highly selective decarboxylation to give corresponding decarboxylated compounds alone in nearly quantitative yields, due to a smaller thermal motion of the radical species in the crystal lattice. Upon irradiating a crystal, a carboxylate radical and hydroacridine or hydrophenanthridine radical are produced via electron transfer from the acid to 1 or 2 and subsequent proton transfer followed by decarboxylation. Next hydrogen abstraction by an active aralkyl radical occurs in highest priority over the shortest distance of 3.2-3.5 A? resulting in the formation of a corresponding decarboxylated product and the regeneration of 1 or 2. Occurrence of radical coupling is low due to the longer coupling distance of 4.5-6.5 A? estimated from the crystallographic data of the starting two-component molecular crystals. The hydrogen abstraction path in the crystal lattice could be confirmed by the reaction of a deuterated crystal 1 · bD in which the CO2H group was replaced by CO2D, giving a deuterated 1-methyl(CH2D)naphthalene as a product. Regeneration of 1 or 2 means that the acceptor plays the role of a stoichiometrical sensitizer, which can act in only one cycle, retaining the initial crystal structure. Such a stoichiometrical sensitization is a novel photochemical process, which occurs specifically in the solid state.
- Koshima, Hideko,Ding, Kuiling,Chisaka, Yosuke,Matsuura, Teruo,Miyahara, Ikuko,Hirotsu, Ken
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p. 10317 - 10324
(2007/10/03)
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- Multiple-Photon Chemistry in the Laser-Jet: Photochemistry and Time-Resolved Laser-Flash Spectroscopy of the 1-Naphthylmethyl Radical
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In the laser-jet (LJ) photolysis (λexc 333, 351, and 364 nm, high intensity) of 1-[(4-benzoylphenoxy)-methyl]naphthalene (1), a two-photon process is observed in CC4 to yield 1-(chloromethyl)-naphthalene (3a) as the main product, while the one-photon products of the conventional photolysis (low intensity) are 1,2-di(1-naphthyl)ethane (2), 1,1,1-trichloro-2-(1-naphthyl)ethane (3b), and 1-naphthaldehyde (5). In MeOH or EtOH, however, our results suggest even a three-photon reaction in which 1-naphthylmethyl methyl ether (4c) and 1-naphthylmethyl ethyl ether (4b) are produced in addition to the one-photon product 2. The three-photon mechanism is based on a competition experiment in which ether 1 was irradiated in mixtures of CCl4 and methanol. The ratio of the two high-intensity products ether 4c and 1-(chloromethyl)naphthalene (3a) showed a strong intensity dependence. We propose that the electronically excited 1-naphthylmethyl radical 1-NpCH2.* is photochemically ionized to 1-naphthylmethyl cation 1-NpCH2+ under the high-intensity LJ photolysis conditions and the latter trapped by the respective alcohols to give the 1-naphthylmethyl ethers 4c and 4b. With the help of time-resolved laser flash photolysis (248 nm) of 1-[(4-benzoylphenoxy)methyl]naphthalene (1), it was established that homolysis of the C-O bond to yield 1-naphthylmethyl (1-NpCH2.) and 4-benzoylphenoxy (ArO.) radicals takes place. The authentic 1-NpCH2. and ArO. radicals were generated independently by pulse radiolysis of 1-(bromomethyl)- or 1-(chloromethyl)naphthalene in 2-propanol and of 4-hydroxybenzophenone (6) in water (1% tBuOH); in the latter case, SO4.- was used as oxidant. In the LJ photolysis, the triplet state of the 1-naphthylmethyl moiety is probably further excited to yield the observed products.
- Adam, Waldemar,Schneider, Katrin,Steenken, Steen
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p. 3727 - 3733
(2007/10/03)
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- Photo-Stevens rearrangement reaction of S-naphthylmethyl-N-p-tosylsulfimides
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Photolysis sulfimides unexpectedly led to Stevens rearrangement products.
- Morita, Hiroyuki,Kamiyama, Hideo,Kyotani, Miho,Fujii, Takayoshi,Yoshimura, Toshiaki,Ono, Shin,Shimasaki, Choichiro
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p. 1347 - 1348
(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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- CLEVEAGE RATES FOR RADIOLYSIS-PRODUCED RADICAL ANIONS OF NAPHTHYLMETHYL PHENYL ETHERS AND NAPHTHYL BENZYL ETHERS
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Cleveage reactions of α- and β-naphthylmethyl phenyl ethers and of α- and β-naphthyl benzyl ethers were studied by pulse radiolysis.Transient spectra indicate that reactions occur via electron capture followed by cleavage of the resultant radical anions to give arylmethyl radicals and aryloxide ions.Product studies of extensively irradiated samples are consistent with this scheme and show patterns which are informative for radiation studies in general.The reactions were studied in several solvents.The behavior of transient spectra obtained in acetonitrile for these ethers shows clearly that radical anions of the naphthylmethyl ethers cleave more rapidly than do the radical anions of the naphthyl benzyl ethers.
- Guthrie, Robert D.,Patwardhan, Manjiri,Chateauneuf, John E.
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p. 147 - 152
(2007/10/02)
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- Intramolecular electron transfer in the photochemistry of substituted 1-naphthylmethyl esters of benzoic acids
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Direct excitation of the esters 5 in methanol solvent leads to rapid intramolecular exciplex formation (kex = 1010 s-1 for X = CH3O, Y = CN) with electron transfer from the naphthalene to the benzoate ring.This process dominates the usual fluorescence and reaction of the excited singlet state.The rate of this process can be varied over 103 by suitable change in the substituents X and Y.The electron-transfer rates can be correlated with the two-parameter Hammett equation: log kex = 8.48 - 1.5?+ + 0.77?.For cases where the rate of exciplex formation is slow, the usual homolytic carbon-oxygen bond cleavage occurs from the excited singlet state.The eventual products result from the ion pair since the rate of electron transfer in the radical pair to form the ion pair is considerably faster than the rate of decarboxylation of the benzoyloxy radical.
- DeCosta, D. P.,Pincock, J. A.
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p. 1879 - 1885
(2007/10/02)
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- W(CO)6 Mediated C-S Bond Cleavage Reactions
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W(CO)6-mediated reactions of thioethers in refluxing chlorobenzene yielded mainly the corresponding dimers.Optically active thioethers give the respective racemic products.Mercaptans, on the other hand, predominantly afford the corresponding reduced products.A deuterium labeling experiments suggest that the SH group is the hydrogen source in the latter reduction reactions.A free-radical mechanism is suggested.
- Ng, Chi Tat,Wang, Xiaojun,Luh, Tien-Yau
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p. 2536 - 2539
(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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- 1-Naphthylcarbene: Spectroscopy, Kinetics, and Mechanisms
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The reactions of 1-naphthylcarbene have been examined by using laser flash photolysis techniques.Generation of the carbene from the diazo precursor in hydrocarbon solvents leads to the formation of 1-naphthylmethyl radicals, which were characterized by their absorption at 363 nm.However, product studies in cyclohexane and cyclohexane-d12 reveal that the main reaction path is carbene insertion into the C-H bond rather than H abstraction. 1-Naphthylcarbene reacts readily with nitriles to yield nitrile ylides which can also be generated from the corresponding azirine.For example, the carbene reacts with acetonitrile with a rate constant of 4.6 X 1E5 M-1s-1 at 300 K to yield an ylide that can be trapped readily with electron-deficient olefins, such as diethyl fumarate.Reaction of the carbene with oxygen (k = 3.5 X 1E9 M-1 s-1) yields the carbonyl oxide (λmax 435 nm).Other reactions examined include halogen abstraction, addition to ketones, and reactions with triethylamine, pyridine, and ethers.The absolute kinetics of the various reactions were examined by monitoring the formation of the products (e.g., ylides, radicals, etc.), since the carbene spectrum was not detected directly.
- Barcus, R. L.,Hadel, L. M.,Johnston, L. J.,Platz, M. S.,Savino, T. G.,Scaiano, J. C.
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p. 3928 - 3937
(2007/10/02)
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- Electron Apportionment in Cleavage of Radical Anions. 2. Naphthylmethyl Phenyl Ethers vs. Naphthyl Benzyl Ethers
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Naphthylmethyl phenyl ethers and naphthyl benzyl ethers were found to undergo scission of the H2C-O bond when treated with radical anions of anthracene or fluoranthene.Under comparable conditions, ethers of the naphthylmethyl phenyl series (α and β) reacted more than 10E4 times faster than ethers of the naphthyl benzyl series (α and β).This preference for regioconservation of spin density in the scission process is interpreted in terms of ?-bond polarization at the transition state.
- Maslak, Przemyslaw,Guthrie, Robert D.
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p. 2637 - 2640
(2007/10/02)
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- Homolytic versus heterolytic cleavage for the photochemistry of 1-naphthylmethyl derivatives
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The photochemical cleavage of the 1-naphthylmethyl derivatives, 1-7, has been examined in methanol solvent under both direct and sensitized conditions.The competition between homolytic and heterolytic cleavage as a function of multiplicity and leaving group has been studied in detail.Only substrates 1, 2, 3, and 7 react on sensitization with xanthone but evidence is presented that the resulting reactivity of 1, 2, and 3 may not be triplet energy transfer but rather exciplex formation.A semi-quantitative scale for photofugacities of the leaving groups from the excited singlet states has been established.
- Arnold, B.,Donald, L.,Jurgens, A.,Pincock, J. A.
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p. 3140 - 3146
(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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- NEW SYNTHETIC METHOD OF PARACYCLOPHANE, BENZOCYCLOBUTENE, AND LEPIDOPTRENE: PYROLYSIS OF ARYLMETHYL PHENYL SELENIDES
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The flash vacuum pyrolysis of benzyl phenyl selenides gave bibenzyls and diphenyl diselenide in excellent yields.This type of reaction was successfully applied to the synthesis of the title compounds.
- Higuchi, Hiroyuki,Sakata, Yoshiteru,Misumi, Soichi,Otsubo, Tetsuo,Ogura, Fumio,Yamaguchi, Hachiro
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p. 627 - 630
(2007/10/02)
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