The Friedel-Crafts Syntheses.

Calloway, N. O.

doi:10.1021/cr60058a002

Cited by 166 publications

(65 citation statements)

References 115 publications

(184 reference statements)

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“…[3] However, two main issues are associated with this approach. Its low regioselectivity leads to the co-manufacture of large amounts of isomeric by-products, and the use of acyl chlorides as starting materials activated with superstoichiometric amounts of salt mediators (e.g., AlCl 3 ) is responsible for the formation of enormous quantities of salt waste.…”

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confidence: 99%

Catalytic Decarboxylative Cross‐Ketonisation of Aryl‐ and Alkylcarboxylic Acids using Magnetite Nanoparticles

2010

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In the presence of catalytic amounts of magnetite nanopowder, mixtures of aromatic and aliphatic carboxylic acids are converted selectively into the corresponding aryl alkyl ketones. As byproducts, only carbon dioxide and water are released. This catalytic cross-ketonisation allows the regioselective acylation of aromatic systems and, thus, represents a sustainable alternative to FriedelCrafts acylations.Keywords: aryl alkyl ketones; catalysis; cross-ketonisation; decarboxylation; iron Aryl alkyl ketones are among the most important synthons in the industrial manufacture of commodities, [1] fine chemicals, and pharmaceuticals.[2] Simple derivatives, at early stages of the chemical value creation chain, are synthesised almost exclusively via FriedelCrafts acylation of arenes, because the low cost of this reaction is unrivalled to date.[3] However, two main issues are associated with this approach. Its low regioselectivity leads to the co-manufacture of large amounts of isomeric by-products, and the use of acyl chlorides as starting materials activated with superstoichiometric amounts of salt mediators (e.g., AlCl 3 ) is responsible for the formation of enormous quantities of salt waste.Regioselective and less waste-intensive acylations, e.g., cross-couplings [4] of sensitive arylmetal reagents with either preformed [5] or in situ-generated [6] carboxylic acid derivatives are widely used to access highervalue synthetic intermediates. However, their high cost precludes their application in the manufacture of base chemicals. This is also the case for alternative approaches, such as Heck-type reactions, [7] or the Pdcatalysed decarboxylative cross-coupling of a-oxocarboxylate salts with aryl halides.[8] Thus, a clear need remained for a broadly applicable, regioselective and waste-minimised aryl alkyl ketone synthesis starting from simple, inexpensive, and widely available chemicals.As a solution to this long-standing problem, we envisioned a catalytic process in which an aromatic and an aliphatic carboxylic acid are cross-coupled under release of CO 2 and water, to selectively give the aryl alkyl ketone (Scheme 1). In such a decarboxylative cross-ketonisation, the carboxylate groups would predefine the position of bond formation, potentially allowing a selective synthesis of any desired regioisomer. If mediated by catalytic amounts of an inexpensive metal with high selectivity for hetero-over homocoupling, the overall process would be advantageous both from economical and ecological standpoints.The decarboxylative homoketonisation of aliphatic carboxylic acids is an established strategy for the preparation of symmetrical dialkyl ketones or cyclic alkanones.[9] State-of-the-art protocols involve gasphase transformations at temperatures above 350 8C at solid catalysts, for example, CaO, ZnO, MgO, [10] TiO 2 , [11] ZrO 2 , [12] MnO, [13] Fe 2 O 3 , [14] or rare earth metal oxides [15] on SiO 2 -, Al 2 O 3 -, or pumice-based supports. However, if equimolar mixtures of aromatic and aliphatic carboxylic acids ar...

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Catalytic Decarboxylative Cross‐Ketonisation of Aryl‐ and Alkylcarboxylic Acids using Magnetite Nanoparticles

2010

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“…Next, aluminum(III) chloride was investigated as a result of its well-established ability to promote oxocarbenium ion formation in Friedel-Crafts acylations. [37][38][39] The desired product was obtained in 62% yield when an aluminum(III) chloride catalyst was employed.…”

Section: Representative Resultsmentioning

confidence: 99%

Metal-Free Synthesis of Ynones from Acyl Chlorides and Potassium Alkynyltrifluoroborate Salts

Taylor

Bolshan

2013

Org. Lett.

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Ynones are a valuable functional group and building block in organic synthesis. Ynones serve as a precursor to many important organic functional groups and scaffolds. Traditional methods for the preparation of ynones are associated with drawbacks including harsh conditions, multiple purification steps, and the presence of unwanted byproducts. An alternative method for the straightforward preparation of ynones from acyl chlorides and potassium alkynyltrifluoroborate salts is described herein. The adoption of organotrifluoroborate salts as an alternative to organometallic reagents for the formation of new carbon-carbon bonds has a number of advantages. Potassium organotrifluoroborate salts are shelf stable, have good functional group tolerance, low toxicity, and a wide variety are straightforward to prepare. The title reaction proceeds rapidly at ambient temperature in the presence of a Lewis acid without the exclusion of air and moisture. Fair to excellent yields may be obtained via reaction of various aryl and alkyl acid chlorides with alkynyltrifluoroborate salts in the presence of boron trichloride. Video LinkThe video component of this article can be found at

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“…Well-known examples of such a transformation are the FriedelCrafts reaction 35 and the hydroarylation of olefins. 36 However, in both cases, it is usually difficult to introduce only one alkyl group into the aromatic rings regioselectively.…”

Section: Regioselective Alkylation Of Phenolsmentioning

confidence: 99%

Development of Novel and Highly Efficient Methods to Construct Carbon–Carbon Bonds Using Group 7 Transition-Metal Catalysts

Kuninobu

Takai

2012

Bulletin of the Chemical Society of Japan

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Rhenium-or manganese-catalyzed transformations based on the cleavage of inactive bonds, such as carbon hydrogen and carboncarbon bonds are discussed. Such transformations are recognized as key methods to realize efficient and powerful reactions. We also reveal novel regio-and/or stereodefined cycloaddition reactions using a rhenium or manganese catalyst. Most of the catalytic activities are typical of rhenium and manganese carbonyl complexes.

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The Friedel-Crafts Syntheses.

Cited by 166 publications

References 115 publications

Catalytic Decarboxylative Cross‐Ketonisation of Aryl‐ and Alkylcarboxylic Acids using Magnetite Nanoparticles

Catalytic Decarboxylative Cross‐Ketonisation of Aryl‐ and Alkylcarboxylic Acids using Magnetite Nanoparticles

Metal-Free Synthesis of Ynones from Acyl Chlorides and Potassium Alkynyltrifluoroborate Salts

Development of Novel and Highly Efficient Methods to Construct Carbon–Carbon Bonds Using Group 7 Transition-Metal Catalysts

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