Competitive acylation of arylstyrylsilanes: Controlling silanucleophile reactivity

Brook, Michael A.; Henry, Courtney

doi:10.1016/0040-4020(95)00945-0

Cited by 7 publications

(3 citation statements)

References 27 publications

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“…A single 31 P NMR resonance signal is observed at 60 ppm for 3b , indicating that the two phosphorus atoms remain symmetrically coordinated to gold. Upon transformation of 2b into 3b , the 29 Si NMR signal shifts to high field (Δδ = 34.2 ppm) to appear in the typical range of organic siloxane derivatives (δ 2.7 ppm for 3b , compared with δ −2.2 ppm for PhMe 2 SiOSiPhMe 2 ) . The coupling pattern of the 29 Si NMR signal also changes drastically.…”

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confidence: 98%

Gold-Mediated Insertion of Oxygen into Silicon–Silicon Bond: An Original Au(I)/Au(III) Redox Sequence

et al. 2012

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The diphosphine−disilane iPr 2 (o-C 6 H 4 )-SiMe 2 SiMe 2 (o-C 6 H 4 )PiPr 2 reacts with AuCl(SMe 2 ) via coordination of the two phosphines and oxidative addition of the σ-Si−Si bond. The ensuing bis(silyl) gold(III) complex has been unequivocally authenticated by NMR spectroscopy at −60°C. Upon heating, it evolves cleanly to give a disiloxane gold(I) complex that has been fully characterized, including by X-ray diffraction analysis. Oxidation of the disilane proceeds via an original Au(I)/Au(III) redox sequence. According to 18 O labeling experiments, both water and dioxygen are competent oxygen sources. Oxidative addition of the σ-Si−Si bond to form a bis(silyl) gold(III) complex seems to be a prerequisite for the disilane → disiloxane conversion to occur. O ver the past decade, homogeneous catalysis with gold complexes has attracted considerable interest and it has been applied to a wide range of organic transformations with very high, often unprecedented efficiency and selectivity. 1 The vast majority of these reactions are based on the unique carbophilic Lewis acidity of gold complexes that is typically used to activate alkynes, alkenes, allenes, etc. toward nucleophilic attack. Recently, the scope and versatility of homogeneous gold catalysis has been further extended, in particular toward oxidative coupling and addition reactions (in the presence of external oxidants) 2 as well as C−C bond forming reactions using dual Au−Pd catalysis. 3 In parallel with these very rapid and important synthetic achievements, increasing efforts have been made over the past few years to shed light into the underlying mechanistic issues. The recent characterization of some putative intermediates involved in gold activation of π systems 4 (side-on complexes, 5 vinyl gold complexes, 6 geminal digold complexes 7 ) has provided valuable information and contributed to refine mechanistic proposals. Comparatively, the precise factors involved in controlling two-electron redox and dual catalysis with gold complexes remain less understood, but some insight has started to be gained into key transformations (oxidative addition/reductive elimination, transmetalation, etc.) 8,9 In that general context, we have recently shown, thanks to phosphine chelating assistance, that gold can undergo unexpectedly facile oxidative addition of σ-Si−Si bonds, affording original bis(silyl) gold(III) complexes. 10,11 Upon varying the substituents at the phosphorus anchors, we have incidentally found that the disilane moiety can be converted into a disiloxane moiety (oxygen insertion) via a Au(I)/Au(III) sequence. These results are reported herein. Labeling experiments have been performed to identify the possible source of the oxygen atom, and the role of gold in the disilane → disiloxane conversion has been probed.As previously reported, 10 the diphosphine−disilane ligand 1a readily reacts with [AuCl(SMe 2 )] in dichloromethane at −78°C via coordination of the two phosphines and oxidative addition of the σ-Si−Si bond at gold (Scheme 1). The ensuing bis(si...

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confidence: 98%

Gold-Mediated Insertion of Oxygen into Silicon–Silicon Bond: An Original Au(I)/Au(III) Redox Sequence

et al. 2012

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“…Treatment of 3 aa with benzoyl chloride in the presence of TiCl 4 in DCM, then subsequent treatment with a Et 2 O/H 2 O solution of triethylamine to quench the reaction led to the removal of the masking group (1‐Np) to achieve the silanol 8 b in 42 % yield, which really increased the practicality and synthetic usefulness of our method. We further proved that the 1‐naphthyl group at the silicon atom of 3 aa can also be directly removed by treatment with an organolithium reagent to yield the vinyltrialkylsilanes 8 c . Furthermore, we investigated whether vinylsilanes can serve as general organosilicon reagents to couple with electrophiles.…”

Section: Methodsmentioning

confidence: 92%

“…Bromination smoothly proceeded to give ( E )‐(2‐bromovinyl)benzene ( 8 a ) in 74 % yield by using NBS as the brominating reagent . Treatment of 3 aa with benzoyl chloride in the presence of TiCl 4 in DCM, then subsequent treatment with a Et 2 O/H 2 O solution of triethylamine to quench the reaction led to the removal of the masking group (1‐Np) to achieve the silanol 8 b in 42 % yield, which really increased the practicality and synthetic usefulness of our method. We further proved that the 1‐naphthyl group at the silicon atom of 3 aa can also be directly removed by treatment with an organolithium reagent to yield the vinyltrialkylsilanes 8 c .…”

Section: Methodsmentioning

confidence: 99%

Divergent Synthesis of Vinyl‐, Benzyl‐, and Borylsilanes: Aryl to Alkyl 1,5‐Palladium Migration/Coupling Sequences

Han

Qin

et al. 2020

Angewandte Chemie

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Organosilicon compounds have been extensively utilized both in industry and academia. Studies on the syntheses of diverse organosilanes is highly appealing. Through‐space metal/hydrogen shifts allow functionalization of C−H bonds at a remote site, which are otherwise difficult to achieve. However, until now, an aryl to alkyl 1,5‐palladium migration process seems to have not been presented. Reported herein is the remote olefination, arylation, and borylation of a methyl group on silicon to access diverse vinyl‐, benzyl‐, and borylsilanes, constituting a unique C(sp3)−H transformation based on a 1,5‐palladium migration process.

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Activating and Directive Effects of Silicon

Bassindale¹,

Glynn²,

Taylor³

2009

Patai's Chemistry of Functional Groups

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Introduction Electronic Effects of R 3 Si The Measurement and Interpretation of R 3 Si Activating and Directive Parameters Activating and Directive Effects of Silicon in Electrophilic Aromatic Substitution Activating and Directive Effects in Aliphatic Electrophilic Reactions Activating and Directive Effects of Silicon in Carbanionic Reactions Stabilization of Developing Negative Charge by Silicon

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Competitive acylation of arylstyrylsilanes: Controlling silanucleophile reactivity

Cited by 7 publications

References 27 publications

Gold-Mediated Insertion of Oxygen into Silicon–Silicon Bond: An Original Au(I)/Au(III) Redox Sequence

Gold-Mediated Insertion of Oxygen into Silicon–Silicon Bond: An Original Au(I)/Au(III) Redox Sequence

Divergent Synthesis of Vinyl‐, Benzyl‐, and Borylsilanes: Aryl to Alkyl 1,5‐Palladium Migration/Coupling Sequences

Activating and Directive Effects of Silicon

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