- Photochemical Strategy for Carbon Isotope Exchange with CO2
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A photocatalytic approach for carbon isotope exchange is reported. Utilizing [13C]CO2 and [14C]CO2 as primary C1 sources, this protocol allows the insertion of the desired carbon isotope into phenyl acetic acids without the need for structural modifications or prefunctionalization in one single step. The exceptionally mild conditions required for this traceless transformation are in stark contrast with those for previous methods requiring the use of harsh thermal conditions.
- Babin, Victor,Talbot, Alex,Labiche, Alexandre,Destro, Gianluca,Del Vecchio, Antonio,Elmore, Charles S.,Taran, Frédéric,Sallustrau, Antoine,Audisio, Davide
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p. 2968 - 2976
(2021/03/09)
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- Dramatic Synergy in CoPt Nanocatalysts Stabilized by "click" Dendrimers for Evolution of Hydrogen from Hydrolysis of Ammonia Borane
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Hydrolysis of ammonia borane (AB) is a very convenient source of H2, but this reaction needs catalytic activation to become practical under ambient conditions. Here this reaction is catalyzed by bimetallic late transition-metal nanoparticles (N
- Wang, Qi,Fu, Fangyu,Yang, Sha,Martinez Moro, Marta,Ramirez, Maria De Los Angeles,Moya, Sergio,Salmon, Lionel,Ruiz, Jaime,Astruc, Didier
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p. 1110 - 1119
(2019/01/21)
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- N-benzylation/benzylic C-H amidation cascade by the (ζ3- Benzyl)palladium system in aqueous media: An effective pathway for the direct construction of 3-phenyl-3,4-dihydro-(2H)-1,2,4-benzothiadiazine 1,1-dioxides
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We demonstrate a unique strategy for a benzylation/benzylic C-H amidation cascade reaction by the (ζ3-benzyl)palladium system derived from a palladium catalyst and benzyl alcohol. This tandem process is devised as a new synthetic route for 3-phenyl-3,4-dihydro-(2H)-1,2,4-benzothiadiazine-1,1- dioxide. Water plays an important role for the smooth generation of the (ζ3-benzyl)palladium species, and a bis-benzylated Pd(II) intermediate would be formed in our catalytic system. Atom economical processes such as benzylic C-H activation, cascade reactions and chemoselective reactions in aqueous media have been developed.
- Hikawa, Hidemasa,Matsuda, Naoya,Suzuki, Hideharu,Yokoyama, Yuusaku,Azumaya, Isao
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supporting information
p. 2308 - 2320
(2013/10/01)
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- Pd-catalyzed benzylic C-H amidation with benzyl alcohols in water: A strategy to construct quinazolinones
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A novel method for the synthesis of 4-phenylquinazolinones via a palladium-catalyzed domino reaction of o-aminobenzamides with benzyl alcohols is developed. This protocol involves N-benzylation, benzylic C-H amidation, and dehydrogenation in water, which may play an important role in the smooth generation of the (η3-benzyl)palladium species by activation of the hydroxyl group of the benzyl alcohol.
- Hikawa, Hidemasa,Ino, Yukari,Suzuki, Hideharu,Yokoyama, Yuusaku
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p. 7046 - 7051
(2012/10/07)
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- Reaction of 1,2-Diphenylethane with D2
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The reaction of 1,2-diphenylethane (DPE) with D2 (2000 psi) was studied at 450 deg C.The results of GC/MS and NMR analysis of reaction products and of products from reactions of 1,2-diphenylethane-1,1-d2, 1,2-di(phenyl-d5)ethane, and 1,2,3,4-tetraphenylbutane confirm a mechanistic scheme in which the main process for introduction of D is the reaction of 1,2-diphenylethyl radical with D2.This reaction, though energetically uphill, competes with termination processes because of the high concentration of D2 relative to that of radical species.The reaction generates D atoms which attack aromatic ring positions to give substitution for both H and alkyl substituents.Evidence is provided for D and H atom transfer between aliphatic positions in DPE in the presence of either N2 or H2 and between aromatic positions only when provoked by H2 or D2.Only a small amount of exchange between aromatic and aliphatic positions is observed under any conditions.The attack of D atoms at H-carrying aromatic positions makes H atoms available for transfer to other aromatic positions.The process results in a D2-provoked generation of benzene-d0.Mechanistic alternatives for these and other processes are discussed.
- Guthrie, Robert D.,Shi, Buchang,Rajagopal, Venkatsubramanian,Ramakrishnan, Sreekumar,Davis, Burtron H.
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p. 7426 - 7432
(2007/10/02)
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- Primary and Secondary Kinetic Isotope Effects in the Decomposition of a Tertiary Alkoxide
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Kinetic isotope effects have been determined for the elimination of toluene from the alkoxide of 1,2,3-triphenylpropan-2-ol (1a).In DMSO, the rate measurements on 1a and 1,2,3-triphenylpropanol (1b) at 30 deg C give kH4/kC4/
- Ibrahim, Sani,Msayib, Kadhum J.,Watt, C. Ian F.,Wilson, John M.
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p. 1703 - 1714
(2007/10/02)
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- Primary and Secondary Kinetic Hydrogen Isotope Effects in the Solution and Gas Phase Decomposition of t-Alkoxides
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Primary and secondary kinetic hydrogen isotope effects (k.i.e.s) in the elimination of toluene from the alkoxide of 1,2,3-triphenylpropane-2-ol have been determined and are consistent with rate limiting proton transfer in gas phase reaction and with rate limiting carbon-carbon bond cleavage in reaction in dimethyl sulphoxide (DMSO) solution.
- Ibrahim, Sani,Watt, C. Ian F.,Wilson, John M.,Moore, Colin
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p. 161 - 163
(2007/10/02)
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- Side Chain Hydroxylation of Aromatic Hydrocarbons by Fungi. Part 2. Isotope Effects and Mechanism
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The benzylic hydroxylation of ethylbenzene, p-diethylbenzene, tetralin, indane, and toluene by the fungi Mortierella isabellina, Cunninghamella echinulata, and Helminthosporium species has been investigated by the use of deuterium-labelled substrates.An i
- Holland, Herbert L.,Brown, Frances M.,Munoz, Benito,Ninnis, Ronald W.
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p. 1557 - 1564
(2007/10/02)
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- Primary and Secondary Kinetic Deuterium Isotope Effects and Transition-State Structures for Benzylic Chlorination and Bromination of Toluene
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As a chemical model for benzylic hydroxylations effected by cytochrome P-450 enzymes, the chlorination of PhCH3, PhCH2D, PhCHD2, and PhCD3 in a two-phase system of hypochlorite/CH2Cl2 with a phase-transfer catalyst has been investigated.On the basis of th
- Hanzlik, Robert P.,Schaefer, Angela R.,Moon, Joseph B.,Judson, Charles M.
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p. 4926 - 4930
(2007/10/02)
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- Intramolecular Kinetic Deuterium Isotope Effects on Microsomal Hydroxylation and Chemical Chlorination of Toluene-α-d1 and Toluene-α,α-d2
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Deuterated toluenes PhCH2D and PhCHD2 were synthesized and subjected separately to microsomal hydroxylation in vitro.Mass spectral analysis of the resulting benzyl alcohols indicated substatial excess retention of deuterium, a consequence of the combined
- Hanzlik, Robert P.,Hogberg, Kerstin,Moon, Joseph B.,Judson, Charles M.
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p. 7164 - 7167
(2007/10/02)
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- Effect of the internal rotation of the CHD2 group on the aliphatic CH stretching mode of the toluenes C6H5CHD2 and C6D5CHD2 in solid crystalline phases
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The infrared and Raman spectra of the toluenes C6H5CHD2 and C6D5CHD2 in the aliphatic CH stretching mode range have been recorded in a large temperature range (17 to 175 K) for both crystalline phases α and β.At very low temperature, the β form spectra show three bands; each of them is assigned to the vibration of a CH oscillator localized in a different site.Three groups of bands are also observed in the α phase spectra: a single band at higher frequency and two doublets at lower frequency.This splitting is assigned to the existence of two types of molecules in the unit cell, involving six different CH vibrators.A quantum theory of these spectra is carried out, assuming an anharmonic coupling of the CH stretching mode with the CHD2 torsion.As a consequence of this coupling, in the adiabatic approximation, the vibrational energy depends on the conformation and can be considered as an additional torsional potential.This latter has no ternary symmetry so that the total torsional potential has three princopal unequal wells that correspond to three different locations of the CH oscillator.Therefore, no tunneling effect appears, which is in agreement with the classical interpretation.Furthermore, this theory ascribes the temperature dependence of the relative intensities of the νCH bands to the population density of the first torsional levels in the vibrational ground state and suggests that, at very low temperature, the isotopic system gets ordered.At higher temperature, a strong relaxation of the νCH vibration bands is observed.This relaxation is much stronger than that of the aromatic ring modes.Thus the relaxation process is essentially due to the influence of the anharmonic coupling between the CH stretching mode and the τCHD2 mode.Two mechanisms are considered: the first one involves Markovian jumps of the system from an equilibrium position to another one, the second one involves fluctuations of the CH vibration around each of these equilibrium positions.NMR and neutron scattering data have already been analyzed on the basis of the first process.Starting from the residence times so determined, the computations show that this mechanism is an efficient relaxation process, but indicate that it is not sufficient to fit the experimental profiles.This fit is obtained rather by using the second model with parameters of reasonable physical values; thus, the second process is also efficient.A better treatment of the relaxation process would be to elaborate; it would have to include both mechanisms and to take into account motions of the methyl group with different amplitudes.
- Cavagnat, D.,Lascombe, J.
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p. 4336 - 4348
(2007/10/02)
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- VEREINFACHUNG DER 1H- UND 13C-NMR-SPEKTREN VON BENZYLETHER-BLOCKIERTEN SACCHARIDEN. EINE LEISTUNGSFAEHIGE SYNTHESE VON BROMMETHYL-d2-BENZOL
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An efficient synthesis of bromomethyl-d2-benzene as reagent for protection of hydroxyl groups and its benefit in (1)H- and (13)C-NMR-spectroscopical analysis of benzylether blocked saccharides is described.
- Paulsen, Hans,Roeben, Wolfgang,Heiker, Fred R.
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p. 3679 - 3680
(2007/10/02)
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