Impact of Silyl Enol Ether Stability on Palladium-Catalyzed Arylations

Guo, Yong; Tao, Guo‐Hong; Blumenfeld, Alex; Shreeve, Jean’ne M.

doi:10.1021/om1000259

Cited by 35 publications

(15 citation statements)

References 30 publications

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“…54 Because the electrophilicity and steric size of the silicon reagent is easily tuned, the choice of silicon reagent could be used to match or differentiate the reactivity of two different substrates or improve selectivity of poorly selective reactions.…”

Section: Discussionmentioning

confidence: 99%

Nickel-Catalyzed Reductive Conjugate Addition to Enones via Allylnickel Intermediates

2013

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An alternative method to copper-catalyzed conjugate addition followed by enolate silylation for the synthesis of β-di-substituted silyl enol ether products (R1(R2)HCCH=C(OSiR43)R3) is presented. This method uses haloarenes instead of nucleophilic aryl reagents. Nickel ligated to either neocuproine or bipyridine couples an α,β-unsaturated ketone or aldehyde (R2HC=CHC(O)R3) with an organic halide (R1-X) in the presence of a trialkylchlorosilane reagent (Cl-SiR43). Reactions are assembled on the bench-top and tolerate a variety of functional groups (aldehyde, ketone, nitrile, sulfone, pentafluorosulfur, and N-aryltrifluoroacetamide), electron-rich iodoarenes, and electron-poor haloarenes. Mechanistic studies have confirmed the first example of a catalytic reductive conjugate addition of organic halides that proceeds via an allylnickel intermediate. Selectivity is attributed to: 1) rapid, selective reaction of LNi0 with chlorotriethylsilane and enone in the presence of other organic electrophiles, and 2) minimization of enone dimerization by ligand steric effects.

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Section: Discussionmentioning

confidence: 99%

Nickel-Catalyzed Reductive Conjugate Addition to Enones via Allylnickel Intermediates

2013

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“…6 A similar approach provided tetrasubstituted silyl fluoroenol ethers that were isolated in good yields and with a high E selectivity (Scheme 3). 7 The increased stability of enoxysilanes 7 could be due either to the bulkier silicon groups that were used or to the higher degree of substitution compared to the previous examples.…”

Section: Enolization/trapping Of Carbonyl Derivativesmentioning

confidence: 98%

“…The yields of the resulting α-aryl-α,α-difluoroketones were high, with the exception of α-bromostyrene (Scheme 95). 116 Scheme 89 The same authors extended the methodology to monofluorinated enol ethers, first with cyclic substrates and then with acyclic ones. In the first case, TES-enol ethers and high catalyst loadings were mandatory for a successful reaction but acyclic enol ethers failed to react even under these conditions.…”

Section: Pd-catalyzed Arylation and Allylation Reactionsmentioning

confidence: 99%

Fluorinated enol ethers: their synthesis and reactivity

2015

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Thanks to the beneficial effect of fluorine substitution on the pharmacokinetic properties of molecules, an ever increasing number of marketed drugs incorporate a fluorine atom into their structure. As a consequence, the synthesis of fluorinated molecules has become a very active research field. Among the numerous approaches, fluorinated enol ethers are valuable building blocks that allow the introduction of a fluoro- or difluoromethyl group through a wide variety of reactions. The present review lists different methods for their preparation and sums up their numerous synthetic applications.

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“…[51] Fluorinated silyl enol ethers derived from cyclic ketones, such as tetralone, indanone, and cyclohexanone, underwent α‐arylation in moderate to good yields, but acyclic enolates underwent α‐arylation in poor yields. This limitation was addressed one year later, when Shreeve reported α‐arylations with acyclic α‐fluoro silyl enol ethers bearing bulky dimethylphenylsilyl groups in high yield [52] …”

Section: Cross Couplingmentioning

confidence: 99%

Transition‐Metal‐Catalyzed Monofluoroalkylation: Strategies for the Synthesis of Alkyl Fluorides by C−C Bond Formation

2021

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Alkyl fluorides modulate the conformation, lipophilicity, metabolic stability, and pKa of compounds containing aliphatic motifs and, therefore, have been valuable for medicinal chemistry. Despite significant research in organofluorine chemistry, the synthesis of alkyl fluorides, especially chiral alkyl fluorides, remains a challenge. Most commonly, alkyl fluorides are prepared by the formation of C−F bonds (fluorination), and numerous strategies for nucleophilic, electrophilic, and radical fluorination have been reported in recent years. Although strategies to access alkyl fluorides by C−C bond formation (monofluoroalkylation) are inherently convergent and complexity‐generating, they have been studied less than methods based on fluorination. This Review provides an overview of recent developments in the synthesis of chiral (enantioenriched or racemic) secondary and tertiary alkyl fluorides by monofluoroalkylation catalyzed by transition‐metal complexes. We expect this contribution will illuminate the potential of monofluoroalkylations to simplify the synthesis of complex alkyl fluorides and suggest further research directions in this growing field.

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Impact of Silyl Enol Ether Stability on Palladium-Catalyzed Arylations

Cited by 35 publications

References 30 publications

Nickel-Catalyzed Reductive Conjugate Addition to Enones via Allylnickel Intermediates

Nickel-Catalyzed Reductive Conjugate Addition to Enones via Allylnickel Intermediates

Fluorinated enol ethers: their synthesis and reactivity

Transition‐Metal‐Catalyzed Monofluoroalkylation: Strategies for the Synthesis of Alkyl Fluorides by C−C Bond Formation

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