69838-89-7Relevant articles and documents
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.).
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.
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.
