69838-89-7Relevant academic research and scientific papers
Cobalt-Catalyzed Reductive Carboxylation of Aryl Bromides with Carbon Dioxide
Hang, Wei,Yi, Yaping,Xi, Chanjuan
supporting information, p. 2337 - 2341 (2020/04/30)
Cobalt-catalyzed reductive carboxylation of aryl bromides with carbon dioxide has been developed. The reaction proceeded under one atm pressure of CO2 at 40 °C in the presence of cobalt iodide/2,2′-bipyridine catalysts and zinc dust as a reducing reagent. Various aryl bromides could be converted to the corresponding carboxylic acids in good to high yields. Preliminary mechanistic experiments ruled out intervention of intermediate organozinc species for carboxylation with CO2, thus suggesting a direct CO2 insertion into the corresponding ArCoBr species. (Figure presented.).
Catalytic Decarboxylation/Carboxylation Platform for Accessing Isotopically Labeled Carboxylic Acids
Tortajada, Andreu,Duan, Yaya,Sahoo, Basudev,Cong, Fei,Toupalas, Georgios,Sallustrau, Antoine,Loreau, Olivier,Audisio, Davide,Martin, Ruben
, p. 5897 - 5901 (2019/06/17)
An integrated catalytic decarboxylation/carboxylation for accessing isotopically labeled carboxylic acids with13CO2 or14CO2 is described. The method shows a wide scope under mild conditions, even in the context of late-stage functionalization, and does not require stoichiometric organometallics, thus complementing existing carbon-labeling techniques en route to carboxylic acids.
Kinetic isotope effects in cycloreversion of rhenium (V) diolates
Gable, Kevin P.,Zhuravlev, Fedor A.
, p. 3970 - 3979 (2007/10/03)
Cycloreversion of 4-methoxystyrene from the corresponding Tp′Re(O)(diolato) complex (Tp′ = hydrido-tris-(3,5-dimethylpyrazolyl)borate) was measured competitively for various isotopomers at 103 °C. Primary (12C/13C) and secondary (1H/2H) kinetic isotope effects were determined. The primary KIEs were k12C/k13C = 1.041 ± 0.005 at the α position and 1.013 ± 0.006 at the β position. Secondary KIEs were kH/kD = 1.076 ± 0.005 at the α position and 1.017 ± 0.005 at the β position. Computational modeling (B3LYP/LACVP*+) located a transition state for concerted cycloreversion of styrene from TpRe(O)(OCH2-CHPh) exhibiting dramatically different C-O bond lengths. A Hammett study on cycloreversions of substituted styrenes from a series of Tp′Re(O)(diolato) showed dichotomous behavior for electron donors and electron-withdrawing groups as substituents: ρ = -0.65 for electron donors, but ρ = +1.13 for electron-withdrawing groups. The data are considered in light of various mechanistic proposals. While the extrusion of 4-methoxystyrene is concluded to be a highly asynchronous concerted reaction, the Hammett study reflects a likelihood that multiple reaction mechanisms are involved.
Studies on the biosynthesis of the antibiotic reductiomycin in Streptomyces xanthochromogenus
Cho,Beale,Graff,Mocek,Nakagawa,Omura,Floss
, p. 12296 - 12304 (2007/10/02)
The biosynthesis of the antibiotic reductiomycin (1) in Streptomyces xanthochromogenus was investigated by feeding experiments with radioactive and stable isotope-labeled precursors. NMR and mass spectroscopic analyses of the labeled 1 samples revealed th
Bis(2,6-difluorophenyl)benzoylmethyl cation: α-ketocarbenium ion as a single-electron acceptor
Kitagawa,Nishimura Takeuchi,Okamoto
, p. 3187 - 3190 (2007/10/02)
The title carbenium ion was observed by low temperature NMR in solution. Its strong oxidizing power was demonstrated by the reduction potential and the effective oxidation of methoxy-substituted benzopinacolone.
One-electron Oxidation of Closed-shell Molecules. Part 3. Oxidative Cleavage of 1,2,2,2-Tetrakis-(p-methoxyphenyl)ethanone with Dibenzoyl and Bis(3,5-dinitrobenzoyl) Peroxides: Mechanistic Changeover of the Peroxide Function from Radical to Molecular Oxidation
Takeuchi, Ken'ichi,Murai, Osamu,Matsui, Shin,Inoue, Takeshi,Kitagawa, Toshikazu,Okamoto, Kunio
, p. 1301 - 1310 (2007/10/02)
1,2,2,2-Tetrakis-(p-methoxyphenyl)ethanone (anispinacolone) (1) is cleaved by dibenzoyl peroxide (2) or bis-(3,5-dinitrobenzoyl) peroxide (3), affording tris-(p-methoxyphenyl)methyl benzoate (or 3,5-dinitrobenzoate) and benzoic (or 3,5-dinitrobenzoic) p-methoxybenzoic anhydride as the principal cleavage products. 13C N.m.r.CIDNP studies by use of labelled anispinacolone (An3*C-*COAn ; *C 90percent 13C) indicated that p-methoxybenzoyl radical is formed, presumably by way of the radical cation +. which is produced by a single-electron transfer (s.e.t.) mechanism.The formation of the p-methoxybenzoyl radical was also indicated by spin-trapping experiments.The decomposition rates of (2) at 50.0 deg C are unaltered on addition of (1) in nonpolar solvents such as dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, and benzene, whereas those of (3) are markedly accelerated.The cleavage of (1) by (2) is supressed by added 3,4-dichlorostyrene by a factor of 6.7, whereas that of (1) by (3) is almost unaffected.These results suggest that in the case of dibenzoyl peroxide (2) the thermally produced benzoyloxyl radical works as a one-electron acceptor (or oxidant) upon (1), whereas when bis-(3,5-dinitrobenzoyl) peroxide (3) is used the peroxide molecule oxidizes (1), probably by way of an s.e.t. mechanism even in such nonpolar solvents.On the other hand, in polar solvents such as (CF3)2CHOH, teramethylene sulphone, and acetonitrile the decomposition of (2) is accelerated by added anispinacolone, suggesting that the intermolecular s.e.t. reaction is partially involved in such polar solvents.Consequently, the oxidative cleavage of anispinacolone (1) by diaroyl peroxides provides the first example of dichotomy in the s.e.t. reaction of diaroyl peroxides, which can be considered a counterpart of the SN1-SN2 dichotomy in nucleophilic substitution, as far as the molecularity of the peroxide is concerned.
