Silylative Coupling Research Articles

Unexpected and frustrating transformations of double-decker silsesquioxanes

This paper outlines an unexpected type of intramolecular transformation of DDSQ during hydrolytic condensation and surprising catalytic reactivity in silylative coupling.

Application of Green Solvents: PEG and scCO2 in the Mono- or Biphasic Catalytic Systems for the Repetitive Batch Coupling of Vinylsilanes with Vinyl Boronates toward 1-Boryl-1-silylethenes.

A new method for the repetitive batch silylative coupling (trans-silylation) of vinylsilanes with vinyl boronates in the presence of Ru(CO)Cl(H)(PCy3)2 immobilized in poly(ethylene glycols) (PEGs) has been developed. Three PEGs (PEG600, PEG2000, and MPEG2000) with different molecular weights and end groups (MW = 600–2000) were tested as solvents and immobilization media, while an aliphatic solvent (n-hexane or n-heptane) or supercritical CO2 was used for product extraction. By applying 2 mol % of the Ru–H catalyst, it was possible to carry out up to 15 complete runs, with the predominant formation of 1-boryl-1-silylethenes. This immobilization strategy permitted for catalyst reuse and obtaining higher TON values (approximately 660–734) compared to the reaction in conventional solvents (∼50). Detailed kinetic studies of the most effective catalytic system were performed to determine catalyst activity and stability. Moreover, the reactions were carried out in an MPEG2000/scCO2 biphasic system, positively influencing the process sustainability.

Formation of Bifunctional Octasilsesquioxanes via Silylative Coupling and Cross-Metathesis Reaction.

Bifunctional silsesquioxanes create an attractive group of compounds with a wide range of potential applications, and recently they have gained much interest. They are known to be obtained mainly via hydrosilylation, but we disclose novel synthetic protocols based on different but complementary reactions, i.e., cross-metathesis (CM) and silylative coupling (SC). A series of cubic T8 type silsesquioxane derivatives with a broad scope of styryl substituents were synthesized in a one-pot procedure and characterized by spectroscopic and spectrometric methods. All of the new compounds can be obtained in a one-pot manner, which has an attractive impact on the synthetic procedure, as it is economic in terms of the isolation of intermediate products. Additionally, the methodology disclosed here enables the (E)-stereoselective introduction of styrenes derivative to the cubic T8 type core. The presented compounds can be interesting precursors for a further functionalization that may significantly increase the possibility of their application in the design and synthesis of new functional materials.

Reactivity of 1-allylsilatrane in ruthenium-catalyzed silylative coupling with olefins – mechanistic considerations

Abstract We have developed a new effective route for obtaining (E)-vinyl-substituted silatranes via ruthenium-catalyzed silylative coupling of 1-allylsilatrane with olefins. Experimental research allowed us also to propose the mechanism of the process based on stoichiometric reactions.

N-Heterocyclic carbene-based ruthenium-hydride catalysts for the synthesis of unsymmetrically functionalized double-decker silsesquioxanes.

Ruthenium-N-heterocyclic carbene complexes with the generic formula [RuHCl(CO)(NHC)(PCy3)] exhibit a high catalytic activity toward the (E)-selective silylative coupling of divinyl-substituted double-decker silsesquioxanes with two distinctly substituted styrenes. This process leads to a novel class of unsymmetrically functionalized silsesquioxane derivatives.

Synthesis and characterization of new (dimethylsilyl)phenoxy and (dimethyl(vinyl)silyl)phenoxy substituted cyclotriphosphazenes

The routes of synthesis, as well as, spectroscopic and X-ray diffraction characterization of a new group of bis- or hexakis-4-(dimethyl(vinyl)silyl)phenoxy and 4-(dimethylsilyl)phenoxy-substituted cyclotriphosphazenes as a versatile starting substrates for the synthesis of a variety of organic cyclophosphazene derivatives, via catalytic hydrosilylation or silylative coupling processes, is presented.

Highly selective synthesis of substituted (E)-alkenylsilatranes via catalytic trans-silylation and mechanistic implications.

A new route for the synthesis of functionalized alkenylsilatranes has been developed based on ruthenium-catalyzed trans-silylation with olefins. This transformation allowed for the synthesis of new (E)-alkenylsilatranes in good yields and excellent selectivity. Experimental studies concerning the reaction mechanism were carried out and the intermediate ruthenium-silatranyl complex was isolated and characterized. Moreover, detailed DFT calculations regarding the mechanism of the silylative coupling catalytic cycle of silatranes catalyzed by [Ru]-H complexes were also performed.

ChemInform Abstract: A Silicon‐Assisted Synthesis of (E)‐β‐Haloenamides from N‐Vinylamides.

Abstract(E)‐β‐Iodoenamides and (E)‐β‐iodoenimides can be easily obtained from N‐vinyl derivatives (N‐vinylamides and N‐vinylimides) by stereoselective ruthenium‐catalyzed silylative coupling with vinyltrimethylsilane (Marciniec coupling) and subsequent stereospecific silicon—iodine exchange.

ChemInform Abstract: Silylative Coupling of Olefins with Vinylsilanes in the Synthesis of Functionalized Alkenes

AbstractReview: 83 refs.

Ruthenium-catalyzed silylation of 1,3-butadienes with vinylsilanes.

A novel method for the synthesis of 1-silyl-substituted 1,3-butadienes, based on [RuHCl(CO)(PCy3)2]-catalyzed silylative coupling of terminal (E)-1,3-dienes with vinylsilanes, is reported. The reaction provides a facile and straightforward access to (E,E)-dienylsilanes in a highly stereoselective fashion (especially for aryl-substituted dienes) and opens a valuable and general synthetic route for the direct catalytic silylation of conjugated dienes with elimination of ethylene as a single byproduct. Preliminary results on synthetic application of the synthesized silylated 1,3-butadienes in desilylation reactions are described.

ChemInform Abstract: New Protocol for One‐Pot Synthesis of Functionalized Symmetrical 1,4‐Dialkyl‐ or 1,4‐Diaryl‐1,3‐diynes.

AbstractThe title compounds are obtained by a highly selective catalytic silylative coupling of vinylsilanes and terminal alkynes followed by CuCl catalyzed desilylative homocoupling.

Phosphine-stabilized, oxide-supported rhodium catalysts for highly efficient silylative coupling reactions

Oxide-supported rhodium catalysts with excellent activity in silylative coupling reactions have been developed. Reductive pretreatment of the catalysts in the presence of 0.5 equiv triphenylphosphine under a hydrogen atmosphere enhanced and stabilized the catalytic activity. Of the catalysts examined, ceria-supported rhodium had the highest activity in the homo-coupling of vinylsilanes to bis(silyl)ethenes at 170 °C. A zirconia-supported catalyst selectively gave E-1-aryl-2-silylethenes by cross-coupling of vinylsilanes with styrenes at 130 °C, and a high turnover frequency of >8200 h−1 was achieved at 170 °C. Spectroscopic studies revealed that well-dispersed surface rhodium(I) species predominantly formed on ceria or zirconia were transformed into rhodium hydride species, which are believed to be responsible for the high activity. These catalysts were recyclable without loss of activity, and leaching of rhodium species from the catalysts was not observed.

A silicon‐assisted synthesis of (E)‐β‐haloenamides from N‐vinylamides

(E)‐β‐Iodoenamides and (E)‐β‐iodoenimides can be easily obtained from N‐vinyl derivatives (N‐vinylamides and N‐vinylimides) by stereoselective ruthenium‐catalysed silylative coupling with vinyltrimethylsilane (Marciniec coupling) and subsequent stereospecific silicon–iodine exchange. Bromodesilylation of (E)‐β‐silylenimides affords (E)‐β‐bromoenimides, while the analogous reactions involving (E)‐β‐silylenamides lead to decomposition of substrates. N‐Halosuccinimides have been found as the most effective halogenating agents in the desilylation step under mild conditions. The ruthenium‐catalysed silylation/halodesilylation sequence can be performed in a one‐pot procedure. Copyright © 2015 John Wiley & Sons, Ltd.

Silylative coupling of olefins with vinylsilanes in the synthesis of functionalized alkenes

Recent developments in the sequential synthetic strategies including ruthenium-catalyzed silylative coupling followed by desilylation, leading to π-conjugated organic derivatives are presented.

New protocol for one-pot synthesis of functionalized symmetrical 1,4-dialkyl- or 1,4-diaryl-1,3-diynes

A new versatile one-pot protocol for preparation of functionalized 1,4-disubstituted-1,3-diynes via a highly selective catalytic silylative coupling of vinylsilanes and terminal alkynes occurring via [Ru] catalyzed reaction and/or [Ir] catalyzed reaction of iodosilanes with alkynes followed by desilylative homocoupling sequence is presented. Contrary to existing stoichiometric systems, the catalytic conditions for the copper salt mediated homocoupling of trimethylsilylalkyne were elaborated that are very tolerant to various functional groups.

Silylative coupling versus metathesis--efficient methods for the synthesis of difunctionalized double-decker silsesquioxane derivatives.

A series of functionalized dialkenylsilsesquioxanes were obtained by efficient and highly stereoselective silylative coupling and cross-metathesis of divinylsubstituted double-decker silsesquioxanes (DDSQ-2SiVi) with substituted styrenes and other olefins. Both reactions proceed highly stereoselectively and lead to nearly quantitative formation of E isomers. The optimized reaction conditions for styrene were adopted for successful silylative coupling polycondensation of DDSQ-2SiVi with 1,4-divinylbenzene yielding stereoregular cooligomer containing double-decker (silsesquioxyl-silylene)-vinylene-phenylene units.

Iridium-Promoted Conversion of Chlorosilanes to Alkynyl Derivatives in a One-Pot Reaction Sequence

By making use of the catalytic potential of the iridium system [{Ir(μ-Cl)(CO)2}2]/NEt(i-Pr)2 in the synthesis of silyl-functionalized alkynes via silylative coupling of terminal alkynes/diynes with iodosilanes, we propose a new protocol allowing employment of various mono- and dichlorosilanes as reagents. The process is based on a sequence of two reactions occurring simultaneously: i.e., conversion of initial chlorosilane (SiR1nCl4–n) to the appropriate iodosilane via Cl/I nucleophilic substitution and its further conversion to a silylalkyne derivative ((SiR1n(C≡CR2)4–n) via iridium-catalyzed silylative coupling with terminal alkyne. Under optimum conditions, the method has proved to be effective and versatile in the conversion of a wide range of chlorosilanes to a rich portfolio of various corresponding alkynyl-functionalized silicon derivatives. Additionally, NMR studies of the equimolar reaction of a well-defined iridium(I) alkynyl precursor with Me3Si–I revealed that ≡Si–I bond activation in iodosilan...

A highly stereoselective synthesis of new styryl-π-conjugate organosilicon compounds

This work describes very precise and controlled catalytic transformations as useful tools for the synthesis of new trans-π-conjugated molecular and macromolecular organosilicon compounds. Several distyryl-arenes were obtained efficiently via silylative coupling in high yields and with excellent selectivity for new E,E-bis(silyl)arenes.

The first ruthenium-silsesquioxyl complexes – synthesis, structure and mechanistic implications in silylative coupling

The first ruthenium-silsesquioxyl complexes have been synthesised and characterized via spectroscopic and X-ray methods. Mechanistic studies were performed and the complexes obtained were proved to be intermediates in the catalytic cycle of silylative coupling of olefins with vinylsilsesquioxane. Moreover, a mechanism for silylative coupling of styrene with vinylsilsesquioxanes was proposed.

Stereoselective synthesis and luminescence properties of novel trans-regular N-alkylcarbazolylene–silylene–vinylene polymers

Novel trans-stereoregular silylene–carbazolylene–vinylene derivatives (13–15) were synthesized via silylative coupling reaction of 3,6-bis(dimethylvinylsilyl)-N-alkylcarbazole (7–9) catalyzed by ruthenium–hydride complex RuHCl(CO)(PCy3)2 (1). All products were isolated, fully characterized by spectroscopic methods and GPC analyses and their absorption and fluorescence properties were determined.