792-74-5Relevant articles and documents
Analysis of C-F bond cleavages in methylfluorobenzoates-Fragmentation and dimerization of anion radicals using convolution potential sweep voltammetry
Muthukrishnan,Sangaranarayanan
, p. 1664 - 1669 (2010)
The electrochemical reduction of methylfluorobenzoates at glassy carbon electrodes is analyzed using the convolution potential sweep voltammetry (CPSV). The stabilization of the radical anion due to the electron-withdrawing group is shown to lead to intra-molecular stepwise dissociative electron transfer. While methyl 2-fluorobenzoate (ortho isomer) follows EC mechanism, the methyl 4-fluorobenzoate (para-isomer) undergoes electro-dimerization prior to C-F bond cleavage. The first order rate constant for the EC mechanism and the dimerization rate constant for the electro-dimerization are deduced from the classical as well as convolution potential sweep voltammetry. A plausible mechanism of dimerization is suggested. The influence of the electron-withdrawing groups is illustrated by comparing the reduction behaviour of 4-fluorobenzonitrile. The potential energy surfaces and electron density mapping employing Gaussian 03 calculations provide further support for the validation of the mechanism pertaining to C-F bond cleavages.
Harris,Mitchell
, p. 1905,1907 (1960)
Reductive Coupling of Aryl Halides via C—H Activation of Indene
Zhang, Bo-Sheng,Yang, Ying-Hui,Wang, Fan,Gou, Xue-Ya,Wang, Xi-Cun,Liang, Yong-Min,Li, Yuke,Quan, Zheng-Jun
, p. 1573 - 1579 (2021/05/28)
This paper describes the first case of a reductive coupling reaction with indene, a non-heteroatom olefin used as a reducing agent. The scope of the substrate is wide. The homo-coupling, cross-coupling, and synthesis of 12 and 14-membered rings were realized. The control experiment, indene-product curve and density functional theory calculations showed that the η3-palladium indene intermediate was formed by C—H activation in the presence of cesium carbonate. We speculate that the final product was obtained through a Pd (IV) intermediate or aryl ligand exchange. In addition, we excluded the formation of palladium anion (Pd(0)?) intermediates.
Cobalt-Catalyzed Highly Regioselective Three-Component Arylcarboxylation of Acrylate with Aryl Bromides and Carbon Dioxide
Hang, Wei,Liang, Nianjie,Liu, Yuzhou,Xi, Chanjuan
, p. 4941 - 4946 (2021/10/30)
Cobalt-catalyzed regioselective three-component arylcarboxylation of acrylate with aryl bromides and carbon dioxide has been developed. The reaction is carried out by using cobalt chloride as a precatalyst and zinc powder as a reducing reagent under CO2 (1 atm) at 40 °C. A range of aryl bromides are used for this reaction, leading to a series of valuable carboxylic acids with high regioselectivity and functional-group compatibility. Mechanistic experiments and DFT calculations indicate that this arylcarboxylation reaction involves the reaction of CO2 with a cobalt enolate intermediate to form the C?C bond.
A Radical Chain: Mononuclear “Gold Only” Photocatalysis
Dreuw, Andreas,Hashmi, A. Stephen K.,Hoffmann, Marvin,Rominger, Frank,Rudolph, Matthias,Witzel, Sina
supporting information, (2021/12/06)
We herein report an unprecedented reactivity of mononuclear gold catalysts acting as classical catalysts and at the same time as active partners in a radical chain mechanism, whereby gold is the only catalyst. The mechanism of the photo-induced photosensitizer-free “gold only”-catalyzed cross coupling was studied in detail – experimentally and theoretically – based on the reaction between arylboronic acids and aryldiazonium salts. With a systematic set of stoichiometric experiments under various conditions and analytic methods, we could show that this mechanism is initiated by an aryl radical formed in the presence of blue LEDs and MeOH. This aryl radical enters the catalytic cycle to oxidize gold(I) to gold(II). Single electron transfer from gold(II) to the aryldiazonium salt then gives the cationic gold(III) complex by formation of a chain-supporting aryl radical which then is enabled to start a new cycle by oxidation of gold(I) without the need for irradiation. At least every 432 cycles of the radical chain, a new chain-initiating radical has to restart the radical chain. Eventually, the boronic acid is activated by the BF4? anion to transmetalate to gold(III), and reductive elimination delivers the desired product.