364796-61-2Relevant academic research and scientific papers
Versatile and base-free copper-catalyzed α-arylations of aromatic ketones using diaryliodonium salts
Bouquin, Maxime,Jaroschik, Florian,Taillefer, Marc
, (2021)
A ligand and base-free copper catalyzed synthetic method for the efficient α-arylation of aromatic ketones is described. In order to avoid strong bases, ketone-derived silyl enol ethers were employed. Their reaction with diaryliodonium salts as aryl source provided the intermolecular C–C coupling displaying good functional group tolerance and requiring low catalyst loading.
Head-to-Tail Dimerization of 4-Fluoroacetophenone in the KOH/DMSO Superbase Suspension and Related SNAr Reaction
Bidusenko, Ivan A.,Schmidt, Elena Yu.,Ushakov, Igor' A.,Orel, Vladimir B.,Absalyamov, Damir Z.,Vitkovskaya, Nadezhda M.,Trofimov, Boris A.
, p. 3480 - 3485 (2020/06/02)
The head-to-tail autocondensation of 4-fluoroacetophenone in the KOH/DMSO superbase suspension stops on dimerization step affording 4-acetylbenzyl-4'-fluorophenylketone in 96 % yield. Further condensation of the diketone formed is prevented by a weaker electron-withdrawing effect of enolate spacer, –CH=C(OK)–. 2-Fluoro- and 3-fluoroacetophenones are inactive in this reaction. Other superbases of the type MOR/DMSO (M = Na, K; R = H, OBut) are inferior in promotion of this reaction providing 71–76 % yields of the dimeric ketone. Other weak acids like non-fluorinated acylbenzenes prove to be also capable of forming Csp2–Csp3 bond with 4-fluoroacetophenone under similar conditions. This new group of fluorine substitution (SNAr) reaction opens a short and simple route to so far inaccessible aromatic diketones via the nucleophilic substitution of fluorine atom in 4-fluoroacetophenone by available acylbenzenes. The quantum-chemical rationale of the observed substitution process as competing with aldol condensation is suggested.
Internal Alkyne Regio- and Chemoselectivity using a Zwitterionic N-Heterocyclic Carbene Gold Catalyst in a Silver-Free Alkyne Hydration Reaction
Weerasiri, Kushan C.,Chen, Danmin,Wozniak, Derek I.,Dobereiner, Graham E.
, p. 4106 - 4113 (2016/12/30)
An alkyne hydration of terminal and internal alkynes is reported using a zwitterionic N-heterocyclic carbene gold catalyst [(BNHC)Au(SMe2)] in the absence of silver and Br?nsted acid additives. The hydration demonstrates good regioselectivity in alkyne hydration and chemoselectivity for internal alkynes vs. terminal. In addition, (BNHC)Au(SMe2) performs a propargyl alcohol hydration to predominantly form α-hydroxymethyl ketone over the more common Meyer–Schuster rearrangement product. While complex (BNHC)Au(SMe2) is active without silver additives, addition of silver hexafluoroantimonate (AgSbF6) increases reaction rate and decreases selectivity for internal alkyne hydration over terminal substrates. To the best of our knowledge, the rate enhancement of (BNHC)Au(SMe2) by AgSbF6is the first such demonstration of a silver effect for a “halide-free” Au catalyst. (Figure presented.).
Copper-catalyzed coupling of aryl iodides and tert-butyl keto esters: Efficient access to α-aryl ketones and α-arylacetic acid tert-butyl esters
Zhao, Duo,Jiang, Yongwen,Ma, Dawei
, p. 3327 - 3332 (2014/05/06)
CuI/trans-4-hydroxy-l-proline catalyzed coupling of aryl iodides with tert-butyl keto esters proceeded smoothly at 40 °C in DMF, providing α-aryl ketones after acid-promoted deprotection and decarboxylation of tert-butyl ester group. While CuI/2-picolinic acid catalyzed coupling of aryl iodides with tert-butyl acetoacetate at 70 °C in dioxane delivered α-arylacetic acid tert-butyl esters upon spontaneous deacylation. A wide range of functional groups, such as acetyl, methoxy, nitrile, nitro, bromo, and chloro were compatible with the reaction conditions.
Heck reactions of α- or β-substituted enol ethers with aryl bromides catalysed by a tetraphosphane/palladium complex - Direct access to acetophenone or 1-arylpropanone derivatives
Battace, Ahmed,Feuerstein, Marie,Lemhadri, Mhamed,Zair, Touriya,Doucet, Henri,Santelli, Maurice
, p. 3122 - 3132 (2008/02/08)
cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphanylmethyl)cyclopentane/ [PdCl(C3H5)]2 efficiently catalyses the Heck reaction of α- and β-substituted enol ethers with aryl bromides. The arylation of 1-phenyl-1-(trimethylsilyloxy) ethylene led directly to the 2-aryl-1-phenylethanones. Similar reaction rates were observed with electron-rich, electron-deficient or sterically congested aryl bromides. Heck reaction with benzyl isopropenyl ether gave a mixture of isomers. However, this mixture gave selectively the 1-arylpropanones after hydrolysis. Employing β-methoxystyrene, 3-ethoxyacrylonitrile or methyl 3-methoxyacrylate, the regioselective α-arylation of these enol ethers was observed in all cases, but mixtures of (Z) and (E) isomers were generally obtained, which in many cases yielded a single ketone product after acid treatment. The stereoselectivity of this reaction depends on steric and electronic factors, and better stereoselectivities in favour of (Z) isomers were observed with electron-rich or sterically congested aryl bromides. Higher yields were obtained for this reaction with electron-rich or sterically congested aryl bromides than with electron-poor aryl bromides. These observations suggest that the rate-limiting step of the catalytic cycle is not the oxidative addition of the aryl bromide to the palladium complex with these substituted enol ethers. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
Highly regioselective, sequential, and multiple palladium-catalyzed arylations of vinyl ethers carrying a coordinating auxiliary: An example of a heck triarylation process
Nilsson,Larhed,Hallberg
, p. 8217 - 8225 (2007/10/03)
This article describes the development of new auxiliary-accelerated Heck multiarylations by intramolecular presentation of the oxidative addition complex. The introduction of a specific, palladium-coordinating dimethylamino group allows for the desired chelation-accelerated and chelation-controlled tri- and diarylation reactions. We report (a) the first example of a Heck triarylation process, (b) highly selective palladium-catalyzed diarylations of alkyl vinyl ethers, and (c) a very rapid two-phase protocol for the microwave-assisted hydrolysis of amino-substituted, arylated vinyl ethers constituting an entry to diarylated ethanals and substituted desoxybenzoins. X-ray structures and product patterns support the suggested substrate-controlled Heck reaction pathway. The catalyst-directing alkyl dimethylamino functionality was rapidly (1-2 min) and efficiently released by microwave hydrolysis after Heck multiarylation reactions. The liberated aromatic carbonyl compounds were thereafter isolated and fully characterized.
