1626-09-1Relevant articles and documents
THE PREPARATION OF 1,4-DICARBONYL COMPOUNDS BY PHOTOREACTION OF KETONES IN THE PRESENCE OF OXIDANTS
Mitani, Michiharu,Tamada, Mamoru,Uehara, Shin-ichi,Koyama, Kikuhiko
, p. 2805 - 2808 (1984)
Phenyl alkyl ketones were photo-irradiated in the presence of Cr(VI) or Mn(VII) oxidants to yield 1,4-dicarbonyl compounds regiospecifically while 2-octanone gave a regioisomeric mixture of 2,5-, 2,6-, and 2,7-octadiones.
Novel synthetic method for symmetric diketones from benzimidazolium salts and bis-Grignard reagents
Jiang,Shi
, p. 4137 - 4142 (1998)
The reaction of 2-substituted benzimidazolium salts and bis-Grignard reagents is reported and a novel method for the preparation of symmetric diketones from carboxylic acid is provided.
Stereospecific sp3 C–H oxidation with m-CPBA: A CoIII Schiff base complex as pre-catalyst vs. its CoIIICdII heterometallic derivative
Nesterova, Oksana V.,Kasyanova, Katerina V.,Makhankova, Valeriya G.,Kokozay, Vladimir N.,Vassilyeva, Olga Yu.,Skelton, Brian W.,Nesterov, Dmytro S.,Pombeiro, Armando J.L.
, p. 171 - 184 (2018/05/28)
The mono- and binuclear Schiff base complexes [CoL3]·DMF (1) and [CoCdL3Cl2]·0.5H2O (2) were facilely synthesized using zerovalent cobalt and cadmium chloride (for 2) as starting materials and the pre-formed pro-ligand HL (2-methoxy-6-[(methylimino)methyl]phenol, the product of condensation of o-vanillin and methylamine) in air. The compounds were characterized by single crystal X-ray diffraction analysis and spectroscopic methods in solution and in the solid state. Both complexes demonstrate a profound catalytic activity in the stereoselective oxidation of cis-1,2-dimethylcyclohexane (model substrate) with m-CPBA (m-chloroperbenzoic acid) under mild conditions in the presence of promoters of various acidity (HNO3, TFA and HOAc). The heterometallic binuclear CoIIICdII pre-catalyst (2) was more active than the mononuclear CoIII one (1), exhibiting higher products yields up to 51% and excellent stereospecificity (up to 99.2% retention of stereoconfiguration). This result could be associated with a synergistic effect of two different metals in 2. Based on the large obtained kinetic isotope effect and H218O labeling studies, the overall reaction mechanism was proposed to proceed without the participation of free alkyl radicals. The acidity of the promoter was shown to influence catalytic parameters for both 1 and 2 so that the better parameters are achieved with the acid possessing lower pKa values (a stronger acid). The comparison of the catalytic behaviours of 1 and 2 is discussed in detail considering relevant examples from the literature.
Electrochemistry for the generation of renewable chemicals: Electrochemical conversion of levulinic acid
Dos Santos, Tatiane R.,Nilges, Peter,Sauter, Waldemar,Harnisch, Falk,Schr?der, Uwe
, p. 26634 - 26643 (2015/03/30)
The oxidative and reductive electrochemical conversion of levulinic acid to its primary products valeric acid, γ-valerolactone, 2,7-octanedione, 4-hydroxy-2-butanone and 3-buten-2-one is studied in detail. The reactions were performed in aqueous solutions and at ambient temperature, following the principles of green chemistry. The obtained primary reaction products were studied with respect to the oxidative and reductive electrochemical formation of secondary products, such as n-octane, 1-butanol and 1,3-butanediol. It is shown that the choice of electrolyte composition, educt concentration and the nature of the electrode material has a strong influence on the selectivity of product formation. For instance it is demonstrated that in alkaline solutions γ-valerolactone can be gained from levulinic acid at iron electrodes with similar Coulombic efficiency (～20%) but higher selectivity (S = 70%) than on lead (S = 50%). Furthermore, for the first time the electrochemical two-step reaction of levulinic acid to 1-butanol via 4-hydroxy-2-butanone is reported. For some of the reaction pathways the main product is water insoluble, which allows a direct separation of the product and the potential electrolyte reuse in a semi-continuous process. Especially the use of the electrocatalytic hydrogenation may provide a path for the storage of electricity into liquid organic fuels as shown by a basic energetic assessment of all electrochemical conversions.
Bulky, spherical, and fluorinated anion BArF induces 'on-water' activity of silver salt for the hydration of terminal alkynes
Saha, Sayantani,Sarbajna, Abir,Bera, Jitendra K.
supporting information, p. 1444 - 1447 (2014/03/21)
AgBArF displays remarkable 'on-water' activity for catalytic hydration of terminal alkynes although it is ineffective in common organic solvents. Liquid alkynes do not require additive or co-solvent whereas a small amount of ethyl acetate triggers quantitative conversions for solid alkynes.
A new approach to organomanganese compounds: The tellurium/manganese exchange reaction
Silva, Márcio S.,Comasseto, Jo?o V.,Dos Santos, Alcindo A.
experimental part, p. 5426 - 5429 (2010/10/20)
Diorganomanganese compounds react with aryl, vinyl, and alkynyl tellurides in a tellurium/manganese exchange reaction. The new mixed organomanganese reagents react selectively with electrophiles.
Iridium complex-catalyzed addition of water and alcohols to non-activated terminal alkynes
Hirabayashi, Tomotaka,Okimoto, Yoshio,Saito, Akiyo,Morita, Masao,Sakaguchi, Satoshi,Ishii, Yasutaka
, p. 2231 - 2234 (2007/10/03)
The addition of water and alcohols to non-activated terminal alkynes was found to be promoted by an iridium complex combined with Lewis acid and phosphite. Thus, terminal alkynes reacted with water or alcohols to give ketones or ketals, respectively, in good to excellent yields. α,ω-Diyne like 1,7-octadiyne was converted into 1-(2-methyl-cyclopent-1-enyl)ethanone through the intramoleculer aldol condensation of the resulting 2,7-octanedione induced by Lewis acid.
Reductive intramolecular Henry reactions induced by Stryker's reagent
Chung, Wing Ki,Chiu, Pauline
, p. 55 - 58 (2007/10/03)
Conjugate reductions of nitroalkenes by Stryker's reagent are ensued by intramolecular aldol reactions to produce β-nitroalcohols in good yield, constituting the first examples of reductive Henry reactions.
A general study of [(η5-Cp′)2Ti(η 2-Me3SiC2SiMe3)]-catalyzed hydroamination of terminal alkynes: Regioselective formation of Markovnikov and anti-Markovnikov products and mechanistic explanation (Cp′=C (5)H(5), C(5)H(4)Et, C(5)Me(5))
Tillack, Annegret,Jiao, Haijun,Castro, Ivette Garcia,Hartung, Christian G.,Beller, Matthias
, p. 2409 - 2420 (2007/10/03)
A general study of the regioselective hydroamination of terminal alkynes in the presence of [(η5-Cp)2Ti(η2-Me 3SiC2SiMe3)] (1), [(η5-CpEt) 2Ti(η2-Me3SiC2SiMe3)] (CpEt= ethylcyclopentadienyl) (2), and [(η5-Cp*) 2Ti(η2-Me3SiC2SiMe3)] (Cp=pentamethylcyclopentadienyl) (3) is presented. While aliphatic amines give mainly the anti-Markovnikov products, anilines and aryl hydrazines yield the Markovnikov isomer as main products. Interestingly, using aliphatic amines such as n-butylamine and benzylamine the different catalysts lead to a significant change in the observed regioselectivity. Here, for the first time a highly selective switch from the Markovnikov to the anti-Markovnikov product is observed simply by changing the catalyst. Detailed theoretical calculations for the reaction of propyne with different substituted anilines and tert-butylamine in the presence of [(η5-C5H5)Ti(= NR)(NHR)] (R=4-C6H4X; X=H, F, Cl, CH3, 2,6-dimethylphenyl) reveal that the experimentally observed regioselectivity is determined by the relative stability of the corresponding π-complexes 10. While electrostatic stabilization favors the Markovnikov performance for aniline, the steric repulsive destabilization disfavors the Markovnikov performance for tert-butylamine.
Reactions of stabilized Criegee intermediates from the gas-phase reactions of O3 with selected alkenes
Baker,Aschmann,Arey,Atkinson
, p. 73 - 85 (2007/10/03)
The gas-phase reactions of O3 with 1-octene, trans-7-tetradecene, 1,2-dimethyl-l-cyclohexene, and α-pinene have been studied in the presence of an OH radical scavenger, primarily using in situ atmospheric ionization tandem mass spectrometry (API-MS), to investigate the products formed from the reactions of the thermalized Criege intermediates in the presence of water vapor and 2-butanol (1-octene and trans-7-tetradecene forming the same Criege intermediate). With H3O+(H2O)n as the reagent ions, ion peaks at 149 u ([M + H]+) were observed in the API-MS analyses of the l-octene and trans-7-tetradecene reactions, which show a neutral loss of 34 u (H2O2) and are attributed to the α-hydroxyhydroperoxide CH3(CH2)5CH(OH)OOH, which must therefore have a lifetime with respect to decomposition of tens of minutes or more. No evidence for the presence of α-hydroxyhyroperoxides was obtained in the 1,2-dimethyl-1-cyclohexene or α-pinene reactions, although the smaller yields of thermalized Criegee intermediates in these reactions makes observation of α-hydroxyhydroperoxides from these reactions less likely than from the 1-octene and trans-7-tetradecene reactions. Quantifications of 2,7-octanedione from the 1,2-dimethyl-1-cyclohexene reactions and pinonaldehyde from the α-pinene reactions were made by gas chromatographic analyses during reactions with cyclohexane and with 2-butanol as the OH radical scavenger. The measured yields of 2,7-octanedione from 1,2-dimethyl-1-cyclohexene and of pinonaldehyde from α-pinene were 0.110 ± 0.020 and 0.164 ± 0.029, respectively, and were independent of the OH radical scavenger used. Reaction mechanisms are presented and discussed.
