Synthese von Ketonen aus α‐Oxocarboxylaten und Arylbromiden durch Cu/Pd‐katalysierte decarboxylierende Kreuzkupplung

Gooßen, Lukas J.; Rudolphi, Felix; Oppel, Christoph; Rodríguez, Nuria

doi:10.1002/ange.200705127

Cited by 101 publications

(48 citation statements)

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“…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).…”

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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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“…Synthesis of Allyl 2, 3,4,5, Following the general procedure, compound 2a [CAS: 1736-60-3] was synthesized from allyl 2, 3,4,5,6-pentafluorobenzoate (1a, 252 mg, 1.00 mmol). The product was obtained as a colorless liquid; yield: 183 mg (879 mmol, 88%).…”

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confidence: 99%

“…Even lower phosphine amounts gave inferior results (Table 1, entries [1][2][3][4][5]. Systematic variation of the Pd catalyst revealed that Pd 2 A C H T U N G T R E N N U N G (dba) 3 is optimal, although PdA C H T U N G T R E N N U N G (PPh 3 ) 4 and PdA C H T U N G T R E N N U N G (OAc) 2 are also active (Table 1, entries 6-9). Control experiments confirmed that the reaction does not take place in the absence of palladium (Table 1, entry 23).…”

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“…[2] In decarboxylative couplings, organometallic reagents are replaced by simple carboxylates as the nucleophilic coupling partner. This concept has found application in the synthesis of biaryls [3] and aryl ketones, [4] and for introducing allyl and benzyl groups. [5] The catalytic activation of C À O bonds has allowed the replacement of ecologically questionable organohalides by ethers or carboxylates as the carbon electrophiles.…”

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