- Nickel-Catalyzed Enantioselective Cross-Coupling of N-Hydroxyphthalimide Esters with Vinyl Bromides
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An enantioselective Ni-catalyzed cross-coupling of N-hydroxyphthalimide esters with vinyl bromides is reported. The reaction proceeds under mild conditions and uses tetrakis(N,N-dimethylamino)ethylene as a terminal organic reductant. Good functional group tolerance is demonstrated, with over 20 examples of reactions that proceed with >90% ee.
- Suzuki, Naoyuki,Hofstra, Julie L.,Poremba, Kelsey E.,Reisman, Sarah E.
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supporting information
p. 2150 - 2153
(2017/04/27)
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- Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals
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Tetrakis(dimethylamino)ethylene (TDAE 1), has been exploited for the first time as a mild reagent for the reduction of arenediazonium salts to aryl radical intermediates through a single electron transfer (SET) pathway. Cyclization of the aryl radicals produced in this way led, in appropriate substrates, to syntheses of indolines and indoles. Cascade radical cyclizations of aryl radicals derived from arenediazonium salts are also reported. The relative ease of removal of the oxidized by-products of TDAE from the reaction mixture makes the methodology synthetically attractive.
- Mahesh, Mohan,Murphy, John A.,Lestrat, Franck,Wessel, Hans Peter
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supporting information; experimental part
(2010/04/22)
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- Orthoamides. LII. Contributions to the synthesis of carboxylic ortho acid amides
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The formamidinium salts 11a, c as well as the nitrile 12 react with sodiumhydride/dimethylamine in the presence of trimethylborate to give the ortho formic acid amide 3a. The orthoamides 6a and 16 can be prepared from the iminium salts 15 and 14, resp. by the same procedure. Treatment of the azavinylogous formamidinium salt 15 with sodiumhydride and piperidine or morpholine in the presence of trime-thylborate affords the orthoamides 6c and 6d, resp. By transamination of the azavinylogous aminalester 5a are accessible the orthoamides 6b-d. The vinylogous orthocarbonic acid derivative 17 can be obtained from the salt 14 and sodium alcoholates. The action of sodiumhydride, dimethylamine and trimethylborate on the iminium salt 18 produces a mixture of the orthocarbonic acid derivatives 7a, 8a, 9a. When the guanidinium salt 20 is treated with the same reagents the ortho-amides 3a and 10a are obtained. The reduction of the salt 20 with sodiumhydride in the presence of several activating reagents (e.g. tetrabutyl orthotitanate, aluminiumisopropylate, trimethylborate) affords the orthoamide 3a. The reduction of the iminium salts 18 and 24 does not proceed clean, giving mixtures of various orthoformic acid derivatives. The form-amidine 25 can be prepared by reduction of the salt 15 with sodiumhydride/trimethylborate with good yields. By the action of the corresponding carbanions on the guanidinium salt 20 can be obtained the carboxylic acid orthoamides 26-33. By the same procedure the orthoamides of alkyne carboxylic acids 36a-h, j-n are accessible. Wiley-VCH Verlag GmbH, 2000.
- Kantlehner, Willi,Stieglitz, Ruediger,Hauber, Michael,Haug, Erwin,Regele, Claudia
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p. 256 - 268
(2007/10/03)
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- Linear free-energy relationship for electron-transfer processes of pyrrolidinofullerenes with tetrakis(dimethylamino)ethylene in ground and excited states
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Systematic studies of electron-transfer processes in the ground states and excited triplet states of pyrrolidinofullerenes {C60(C3H6N)R [R = H (1), p-C6H4NO2 (2), p-C6H4CHO (3), p-C6H5 (4), p-C6H4Me (5), p- C6H4NMe2 (6)]} with tetrakis(dimethylamino)ethylene (TDAE) have been carried out by steady-state and transient absorption measurements in the visible-NIR region. Analyses of the equilibria of the electron-transfer processes in the ground states indicate that free ion radicals are produced in polar solvents. Photoinduced electron-transfer processes via (T)(C60(C3H6N)R)* were observed by applying a perturbation to the equilibria of the electron-transfer reactions in the ground states by laser flash photolysis. Based on the relationship of the thermodynamic data and kinetic data, the electron-transfer rate constants in the ground states (k(et)/(G)) can be evaluated. The k(et)/(G) values are affected by the substituents to a smaller extent compared with the equilibrium constants (K) in polar solvents; α = 0.6 in Δ log k(et)/(G) = α Δ log K. This α value indicates that the activation energies of forward electron transfer in the ground states vary moderately with the thermodynamic stabilities of (C60(C3H6N)R).-. Electron-transfer rate constants via (T)(C60(C3H6N)R)* which are close to the diffusion-controlled limit, do not show a large substituent effect (α = 0), because of their highly exothermic processes. Such a linear free-energy relationship can be extended to other systems such as (T)(C60(C3H6N)R)*/N,N-dimethylaniline, from which valuable information for electron-transfer processes can be obtained.
- Luo, Chuping,Fujitsuka, Mamoru,Huang, Chun-Hui,Ito, Osamu
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p. 2923 - 2928
(2007/10/03)
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- Energy Requirements for a Chemical Reaction. 2. Electron Transfer to SbF5 and SnCl4
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We have measured the integral reactive cross section for the electron-transfer reaction A + D -> A- + D+, where the electron acceptor A is SnCl4 or SbF5 and the electron donor D is one of three amines.By using seeded nozzle beams we are abble to vary separately the translational and vibrational energies.The cross sections rise rapidly above a threshold which is equal to or just above the thermodynamic, adiabatic threshold for the reaction.Vibrational energy in this region plays little or no role in the reaction.At higher energies the dependence on translational energy levels off and then drops rapidly.In this region an increase in vibrational energy makes a large increase in the cross section.At high energies, some of the product ions dissociate.The ratios of the intensities of the various products depends largely on translational energy even though the overall cross section depends markedly on vibrational energy.
- Hershberger, J. F.,Huh, Y. D.,McAndrew, J. J.,Cross, R. J.,Saunders, M.
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p. 1104 - 1108
(2007/10/02)
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- Reactions with Phosphine Alkylenes, XLV. Reactions of Alkylidenetriphenylphosphoranes with Tetramethylformamidinium Chloride. Synthesis of triphenylphosphonium Chloride and (Formylalkylidene)triphenylphosphoranes
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Phosphonium ylides 1 react with tetramethylformamidinium chloride (2) to form enamine phosphonium chlorides 8 and the formic orthoamide 7.The salts 8 show temperature depending 1H NMR spectra with respect to the protons of the dimethylamino group (hindered rotation around the C - N(CH3)2 bond).Treatment of 8 with acids and subsequently with bases gives rise to the formation of the formyl ylides 19. 8a is deprotonated with sodium amide to give the phosphaallene ylide 20, which reacts with water to yield the phosphane oxide 21, and with methyl iodide stereospecifically to form 8b.
- Bestmann, Hans Juergen,Schmid, Guenter,Oechsner, Helmut,Ermann, Peter
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p. 1561 - 1571
(2007/10/02)
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