Construction of Benzosiloles, Six- and Eight-Membered Silacyclic Skeletons, via a Pd-Catalyzed Intramolecular Mizoroki–Heck Reaction of Vinylsilanes

Shape-persistent contorted ladder polymers are an intriguing and unusual class of polymers. Using catalytic arene-norbornene annulation (CANAL) polymerization and with norbornadiene and dibromoarenes as monomers, we synthesized a series of ladder polymers with fused norbornyl benzocyclobutene backbones and varied conformations. A diaryl spiro-orthocarbonate monomer was used to reorient the ladder backbone perpendicularly to induce three-dimensional kinks, and a p-dibromo-xylene comonomer was used to statistically vary the distance between the spirocyclic kinks in the ladder backbone. Norbornyl benzocyclobutene ladder polymers with no spirocyclic backbone twists possess much more compact conformations than ladder polymers with frequent spirocyclic backbone twists in solution. While spirocyclic twists in the polymer backbone had minor effects on the surface area and microporosity, incorporation of rotatable single bonds in the repeat unit significantly decreased both the surface area and pore volume.

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“…Dry toluene was obtained from a dry solvent system. 4‐bromo‐5‐methylcatechol and 3 were synthesized according to literature procedures.…”

Section: Methodsmentioning

confidence: 99%

Norbornyl benzocyclobutene ladder polymers: Conformation and microporosity

Lai

Liu

Xia

2017

J. Polym. Sci. Part A: Polym. Chem.

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“…Recently, many silylation procedures have appeared that give access to new organosilicon building blocks . Among those, the attractive vinylsilanes are available by methods such as hydrosilylation, Heck coupling, or “soft” silylmetalations (zincation, boration, or stannation).…”

Section: Figurementioning

confidence: 99%

Direct Syn Addition of Two Silicon Atoms to a C≡C Triple Bond by Si−Si Bond Activation: Access to Reactive Disilylated Olefins

et al. 2017

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“…These features are associated with the low-lying LUMOs of the siloles, which originate from orbital interaction between the σ* orbital of the silylene moiety and the π* orbital of the butadiene moiety [5]. The popular synthetic routes to benzo-and dibenzosiloles involve intra-and intermolecular cyclization reactions with transition metal catalysts [6][7][8][9], and the use of a chiral supporting ligand enables the synthesis of siloles with a chiral silicon center [10,11]. In particular, direct Si-C or C-H activation is a powerful method that does not require an activated functional group on the aromatic ring [12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Intramolecular Chain Hydrosilylation of Alkynylphenylsilanes Using a Silyl Cation as a Chain Carrier

et al. 2016

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Diorganyl[2-(trimethylsilylethynyl)phenyl]silanes 1a-c and methyl-substituted phenylsilanes 1d and 1e were treated with a small amount of trityl tetrakis(pentafluorophenyl)borate (TPFPB) as an initiator in benzene to afford the corresponding benzosiloles (2a-e) in moderate to good yields. However, no reaction was observed for the reaction using [2-(1-hexynyl)phenyl]diisopropylsilane lf. The methyl substituent was tolerated under the reaction conditions and increased the yield of the corresponding benzosilole depending on the substitution position. From the result using 1f, the current reaction was found to require the trimethylsilyl group, which can stabilize intermediary alkenyl carbocations by the β-silyl effect. The current reaction can be considered an intramolecular chain hydrosilylation of alkynylarylsilanes involving silyl cations as chain carriers. Therefore, the silyl cations generated by hydride abstraction from hydrosilanes 1 with the trityl cation causes intramolecular electrophilic addition to the C-C triple bond to form ethenyl cations, which abstract a hydride from 1 to afford benzosiloles 2 with the regeneration of the silyl cations.

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Construction of Benzosiloles, Six- and Eight-Membered Silacyclic Skeletons, via a Pd-Catalyzed Intramolecular Mizoroki–Heck Reaction of Vinylsilanes

Abstract: A variety of silacycles including benzosiloles, six- and eight-membered silacyclic skeletons, were efficiently synthesized via a Pd-catalyzed intramolecular Mizoroki-Heck reaction of vinylsilanes.

Cited by 52 publications

References 62 publications

Norbornyl benzocyclobutene ladder polymers: Conformation and microporosity

Norbornyl benzocyclobutene ladder polymers: Conformation and microporosity

Direct Syn Addition of Two Silicon Atoms to a C≡C Triple Bond by Si−Si Bond Activation: Access to Reactive Disilylated Olefins

Intramolecular Chain Hydrosilylation of Alkynylphenylsilanes Using a Silyl Cation as a Chain Carrier

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