Hochaktive Titanocen‐Katalysatoren für Epoxid‐Hydrosilylierungen – Synthese, Theorie, Kinetik, EPR‐Spektroskopie

Henriques, Dina Schwarz G.; Zimmer, Katharina; Klare, Sven; Meyer, Andreas; Rojo‐Wiechel, Elena; Bauer, Mirko; Sure, Rebecca; Schiemann, Olav; Flowers, Robert A.; Gansäuer, Andreas

doi:10.1002/ange.201601242

Cited by 29 publications

(5 citation statements)

References 54 publications

(19 reference statements)

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“…We suggest that coordination of the silane to the hydride results in increased steric interactions and a higher selectivity of hydrogen atom transfer (HAT). This is in line with a previous study that has shown coordination of a Ti‐bonded hydride with PhSiH 3 [4b] . The notion of the coordination also explains why [Cp 2 TiH] outperforms the bulkier catalysts as their interactions with PMHS slow down the rate of the reaction.…”

Section: Resultssupporting

confidence: 91%

“…The solution turned green in less than five minutes. Previous calculations suggest that the σ‐bond metathesis of PhSiH 3 and alkyl titanocene(III) complexes are exergonic or slightly endergonic while the same reactions with (EtO) 3 SiH are strongly endergonic [4b] . Since PMHS is electronically more similar to (EtO) 3 SiH than to PhSiH 3 , it seems that the σ‐bond metathesis of PMHS and [Cp 2 TiBn] is also endergonic.…”

Section: Resultsmentioning

confidence: 98%

“…As a “waste product” it is available at a much lower price (Figure 1) than any other silicon‐ or boron‐based hydrogen donor. This is especially so for Ph(Me)SiH 2 , PhSiH 3 , or BH 3 *NH 3 that have already been used in catalyzed hydrosilylations or hydroborations [4b,c] . While the exact prices may vary on a daily basis, the relative values give a comparison of the cost of the terminal reductant.…”

Section: Resultsmentioning

confidence: 99%

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Polymethylhydrosiloxane (PMHS) as Sustainable Reductant in the Titanocene Catalyzed Epoxide Hydrosilylation

Schacht¹,

Wu²,

Klare³

et al. 2022

ChemCatChem

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Here, we describe that polymethylhydrosiloxane (PMHS) is a sustainable terminal reductant in the titanocene catalyzed hydrosilylation of epoxides. The products formally constitute the anti-Markovnikov products of H 2 O-addition to alkenes.PMHS is not only a more sustainable and cheaper reductant than other silanes such as PhSiH 3 and Ph(Me)SiH 2 . It also results in a higher diastereoselectivity of epoxide reduction.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

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Polymethylhydrosiloxane (PMHS) as Sustainable Reductant in the Titanocene Catalyzed Epoxide Hydrosilylation

Schacht¹,

Wu²,

Klare³

et al. 2022

ChemCatChem

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“…A milder method for the in situ generation of [Cp 2 TiH] from bench stable Cp 2 TiCl 2 employs allylMgBr for the preparation of [Cp 2 Tiallyl] [14] (allyl activation) [15] . This species is then transformed into [Cp 2 TiH] by σ‐bond metathesis with PhSiH 3 .…”

Section: Resultsmentioning

confidence: 99%

Titanocene(III)‐Catalyzed Precision Deuteration of Epoxides

et al. 2021

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We describe atitanocene(III)-catalyzed deuterosilylation of epoxides that provides b-deuterated anti-Markovnikovalcohols with excellent D-incorporation, in high yield, and often excellent diastereoselectivity after desilylation. The key to the success of the reaction is an ovel activation method of Cp 2 TiCl 2 and (tBuC 5 H 4 ) 2 TiCl 2 with BnMgBr and PhSiD 3 to provide[(RC 5 H 4 ) 2 Ti(III)D] without isotope scrambling.Itwas developed after discovering an off-cycle scrambling with the previously described method. Our precision deuteration can be applied to the synthesis of drug precursors and highlights the power of combining radical chemistry with organometallic catalysis.

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“…Based on experimental and computational data, a catalytic cycle for the titanium(III)‐mediated hydrosilylation of epoxides was proposed (Scheme ) . The initial step would involve the generation of a catalytically active species, 6 , upon the reaction of [TiCp 2 R 2 ] with the hydrosilane.…”

Section: Hydrosilylative Reduction Of Epoxidesmentioning

confidence: 99%

Catalytic Reduction of Cyclic Ethers with Hydrosilanes

Park

2019

Chemistry An Asian Journal

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Catalytic reductive transformations of ethers as a synthetic building block are an important class of chemical reactions because a range of essential chemical feedstocks and fuels in contemporary life can be prepared through the key step of ethereal C−O bond cleavage of cellulosic biomass. Although conventional stoichiometric and catalytic methods for sp2‐ and sp3‐C−O bond cleavage of linear ethers and alcohols with hydrosilanes are well established, silylative ring opening of cyclic ethers has been less highlighted in this context. This review outlines catalytic systems for the silylative reduction of a range of cyclic ethers, including epoxides and sugars, leading to the corresponding alcohols and/or hydrocarbons. The chemical reactivity and selectivity of these ring‐opening catalytic processes are discussed with respect to the type of substrates; the representative catalytic working modes are also described.

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Hochaktive Titanocen‐Katalysatoren für Epoxid‐Hydrosilylierungen – Synthese, Theorie, Kinetik, EPR‐Spektroskopie

Cited by 29 publications

References 54 publications

Polymethylhydrosiloxane (PMHS) as Sustainable Reductant in the Titanocene Catalyzed Epoxide Hydrosilylation

Polymethylhydrosiloxane (PMHS) as Sustainable Reductant in the Titanocene Catalyzed Epoxide Hydrosilylation

Titanocene(III)‐Catalyzed Precision Deuteration of Epoxides

Catalytic Reduction of Cyclic Ethers with Hydrosilanes

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