Diaryliodoniumsalze – aus dem Nichts ins Rampenlicht

Merritt, Eleanor A.; Olofsson, Berit

doi:10.1002/ange.200904689

Cited by 297 publications

(42 citation statements)

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“…These intermediates are isoenergetic, and will rapidly isomerize through an h 3 transition state (TS). Somewhat surprisingly, the preferred reductive elimination is by [2,3] rearrangement rather than the alternative [1,2] process. Direct product formation from anionic intermediates E and F is disfavored due to high calculated barriers.…”

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confidence: 95%

“…Either pathway could give intermediate C or D, with oxygen or carbon bonded to iodine. [24] These intermediates could either equilibrate rapidly, or form the product through different reductive elimination mechanisms; [2,3] rearrangement or [1,2] rearrangement, respectively. Initial B3LYP calculations [25] were performed on a model reaction of acetaldehyde enolate with diphenyliodonium chloride in the gas phase and THF, respectively.…”

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confidence: 99%

“…Diaryliodonium salts, which are iodineA C H T U N G T R E N N U N G (III) compounds with two aryl ligands, are versatile arylation agents for a variety of nucleophiles. [3] With the recent development of efficient and general onepot routes to diaryliodonium salts, [3,4] the direct a-arylation of enolates with diaryliodonium salts (Scheme 1) can become an attractive alternative to the methods described above, [3,5] in particular if asymmetric versions of the reaction can be developed. So far, the only viable approaches are built on attaching a chiral aryl group as an auxiliary, [6] or by shifting the enantiodifferentiation away from the CÀC bondforming step.…”

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α‐Arylation by Rearrangement: On the Reaction of Enolates with Diaryliodonium Salts

Norrby¹,

Petersen²,

Bielawski³

et al. 2010

Chemistry A European J

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126

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Surprising equilibration: A new mechanism for the title reaction is supported by DFT calculations and experimental observations. The CI and OI intermediates are isoenergetic and equilibrate quickly. Thus, any chiral information induced in the initial complex will be destroyed. In the final CC bond‐forming step, a [2,3]‐rearrangement from the OI bonded intermediate is slightly preferred over the [1,2]‐elimination from the CI bonded isomer (see scheme).

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α‐Arylation by Rearrangement: On the Reaction of Enolates with Diaryliodonium Salts

Norrby¹,

Petersen²,

Bielawski³

et al. 2010

Chemistry A European J

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126

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“…These salts are readily prepared in a one-step process from commercial materials. [11] Significantly, functionally diverse aryl groups displaying electronrich (2 e,f), electron-deficient (2 h-j) and halogen-containing substituents (2 g,h,k) were transferred in good yield; these latter groups can facilitate subsequent chemoselective processes.…”

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Copper(II)‐Catalyzed meta‐Selective Direct Arylation of α‐Aryl Carbonyl Compounds

et al. 2010

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Substituted arenes dominate the properties of many natural products, medicines, and materials.[1] Therefore, the development of new methods for direct and selective aromatic functionalization is a persistent challenge for synthetic chemists.[2] A particularly important class of substituted aromatic compounds is the a-aryl carbonyl structure. These molecules represent broadly useful starting materials for complex molecule synthesis, and the basic structural framework is present in a wide range of medicinally relevant molecules.[3] Despite the importance of these structures, surprisingly few direct methods are available to selectively functionalize the arene nucleus in the absence of other groups: aromatic substitution reactions require directing functionality to control reactivity and selectivity; cross coupling processes need pre-installed functional groups; and while the acidity of the CÀH bonds between the arene and carbonyl groups facilitates a wealth of enolate chemistry, it precludes the use of directed ortho-lithiation reactions. [4] A potential solution to some of these limitations has recently been presented through the development of orthoselective Pd II -catalyzed C À H bond functionalization reactions. [5,6] The cyclometalation strategy employed in these transformations, however, cannot be used to facilitate metaor para-functionalization of these molecules due to restrictive geometric constraints. [7,8] The synthetic utility of the generic a-aryl acetic acid motif would be significantly expanded by a methodology that provides direct access to isomeric molecules of potentially beneficial therapeutic value (Scheme 1 A). Herein, we report a copper-catalyzed meta-selective arylation of the a-aryl carbonyl scaffold with diaryliodonium salts that is directed by a remote and versatile Weinreb amide group (Scheme 1 B). This method provides a novel synthetic route to arenes displaying diverse substitution, benzylic chirality and quaternary centers. Its potential is further enhanced through its compatibility with iterative C À H bond functionalization methods that will have broad utility in the synthesis of highly functionalized arenes.As part of our studies towards meta-selective functionalization processes, [8d] we postulated that the location of a carbonyl group plays a key role in determining the selectivity of our Cu II -catalyzed meta-arylation of pivanilides. To test this hypothesis, we speculated that the a-aryl carbonyl would also provide a similar reactivity platform because the carbonyl motif is displayed in a similar position relative to the arene nucleus. Notably, the arene nucleophilicity of the electronically neutral a-aryl carbonyl motif is drastically different to the electron-rich pivanilide.To test whether a-aryl carbonyl compounds could be functionalized at the meta-position, we prepared diethylamide 1 a and treated it with diphenyliodonium triflate and 20 mol % Cu(OTf) 2 in dichloroethane at 70 8C, conditions that are identical to those used for the arylation of pivanilides.[8d]After reacti...

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“…Erst kürzlich wurde entdeckt, dass sie an Übergangsmetall-katalysierten Umwandlungen teilnehmen kçnnen, wodurch sich neue Mçglichkeiten auf diesem Gebiet ergeben (Schema 1). [1] Gaunt und Mitarbeiter verwendeten als Erste Kupferkatalysatoren in Kombination mit Ar 2 IX, um unter milden Bedingungen ein elektrophiles Arylierungsreagens zu generieren. [2] Dessen hohe Reaktivität ermçglicht die Arylierung von verschiedenen latenten Nucleophilen, unter anderem von (Hetero-)Arenen, [2,3] Alkenen, [4] Enaminen [5] und Silylenolethern.…”

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Chirale Aryl‐Kupfer(III)‐Elektrophile: neue Möglichkeiten für katalytische enantioselektive Arylierungen und Dominoprozesse

2012

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Diaryliodoniumsalze – aus dem Nichts ins Rampenlicht

Cited by 297 publications

References 219 publications

α‐Arylation by Rearrangement: On the Reaction of Enolates with Diaryliodonium Salts

α‐Arylation by Rearrangement: On the Reaction of Enolates with Diaryliodonium Salts

Copper(II)‐Catalyzed meta‐Selective Direct Arylation of α‐Aryl Carbonyl Compounds

Chirale Aryl‐Kupfer(III)‐Elektrophile: neue Möglichkeiten für katalytische enantioselektive Arylierungen und Dominoprozesse

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