1072-85-1Relevant articles and documents
Exchange of halogens between aromatic compounds in the presence of Cu-HZSM-5 zeolite
Imhaoulne,Imhaoulene,Vivier,Guisnet,Petot,Perot,Gubelmann
, p. 12913 - 12922 (1994)
The reactions between various haloaromatics in binary mixtures which were approximately equimolar, were studied in gas-phase (673 K, atmospheric: pressure) in the presence of a 2 wt % Cu-HZSM-5 zeolite. The exchange of halogens (ipso substitution) between the two compounds was assumed to occur either through a radical mechanism involving an electron transfer between an atom of copper (I) and one aromatic molecule or through a nucleophilic substitution involving arylcopper complexes as intermediates.
Hydroxyl radical induced reactions with 1-bromo-2-fluorobenzene in aqueous solutions: Formation of radical cations
Mohan, Hari,Mittal, Jai P.
, p. 263 - 270 (1996)
Hydroxyl radicals are observed to react with 1-bromo-2-fluorobenzene to form C6H4BrF · OH and (C6H4BrF)+· in neutral and acidic solutions respectively. The nature and reactivity of the solute radical cation, (C6H4BrF)+·, formed under different acidic conditions are discussed.
Substrate Selectivity and Orientation in Aromatic Substitution by Molecular Fluorine
Cacace, F.,Giacomello, P.,Wolf, A. P.
, p. 3511 - 3515 (1980)
Direct elemental fluorination of representative aromatic substrates, including PhH, PhCH3, PhF, PhCl, PhBr, PhNO2, PhCN, and PhOCH3, has been investigated in inert solvents, e.g., CCl3F and other fluorocarbons, over the temperature range -154 to 40 deg C.In order to achieve the necessary control of the extremely reactivve electrophile, and to minimize unwanted modifications of the reaction environment, the fluorination has been carried out at extremely low rate and correspondingly low conversions, generally below 0.01percent, using as a reagent gaseous mixtures of F2 highly diluted (+ constants for all the substituents investigated, giving a ρ+ value of -2.45 for aromatic substitution by elemental fluorine with a correlation coefficient of 0.993.These results characterize F2 as a highly reactive, and correspondently unselective, reagent, and support a polar electrophilic substitution mechanism that is discussed and compared with other plausible fluorination pathways.
Fluorination of arylboronic esters enabled by bismuth redox catalysis
Planas, Oriol,Wang, Feng,Leutzsch, Markus,Cornella, Josep
, p. 313 - 317 (2020)
Bismuth catalysis has traditionally relied on the Lewis acidic properties of the element in a fixed oxidation state. In this paper, we report a series of bismuth complexes that can undergo oxidative addition, reductive elimination, and transmetallation in a manner akin to transition metals. Rational ligand optimization featuring a sulfoximine moiety produced an active catalyst for the fluorination of aryl boronic esters through a bismuth (III)/bismuth (V) redox cycle. Crystallographic characterization of the different bismuth species involved, together with a mechanistic investigation of the carbonfluorine bond-forming event, identified the crucial features that were combined to implement the full catalytic cycle.
Palladium-catalysed electrophilic aromatic C-H fluorination
Yamamoto, Kumiko,Li, Jiakun,Garber, Jeffrey A. O.,Rolfes, Julian D.,Boursalian, Gregory B.,Borghs, Jannik C.,Genicot, Christophe,Jacq, Jér?me,Van Gastel, Maurice,Neese, Frank,Ritter, Tobias
, p. 511 - 514 (2018/03/02)
Aryl fluorides are widely used in the pharmaceutical and agrochemical industries, and recent advances have enabled their synthesis through the conversion of various functional groups. However, there is a lack of general methods for direct aromatic carbon-hydrogen (C-H) fluorination. Conventional methods require the use of either strong fluorinating reagents, which are often unselective and difficult to handle, such as elemental fluorine, or less reactive reagents that attack only the most activated arenes, which reduces the substrate scope. A method for the direct fluorination of aromatic C-H bonds could facilitate access to fluorinated derivatives of functional molecules that would otherwise be difficult to produce. For example, drug candidates with improved properties, such as increased metabolic stability or better blood-brain-barrier penetration, may become available. Here we describe an approach to catalysis and the resulting development of an undirected, palladium-catalysed method for aromatic C-H fluorination using mild electrophilic fluorinating reagents. The reaction involves a mode of catalysis that is unusual in aromatic C-H functionalization because no organometallic intermediate is formed; instead, a reactive transition-metal-fluoride electrophile is generated catalytically for the fluorination of arenes that do not otherwise react with mild fluorinating reagents. The scope and functional-group tolerance of this reaction could provide access to functional fluorinated molecules in pharmaceutical and agrochemical development that would otherwise not be readily accessible.
