Silylation of Styrene with Vinylsilanes Catalyzed by RuCl(SiR₃)(CO)(PPh₃)₂ and RuHCl(CO)(PPh₃)₃

Abstract

The coupling reaction of styrene with vinylsilanes catalyzed by ruthenium complexes was investigated. RuHCl(CO)(PPh3)3 (I) and RuCl(SiR3)(CO)(PPh3)2 (where R3 = Me3 (II), Me2Ph (III), (EtO)3 (IV)) were found to be efficient and selective catalysts for the formation of E-1-phenyl-2-silylethene and evolution of ethene. Stoichiometric reactions of styrene with the Ru−Si bonds of II−IV in argon and silylstyrene with the Ru−H bond in air (I*) as well as a MS study of the product of the deuterated styrene with vinylsilanes are convincing evidence for the mechanism of the process involving the migratory insertion of styrene into the Ru−Si bond (and vinylsilane into Ru−H bond) followed by β-H (and β-Si) elimination to give phenylsilylethene (and ethene). Kinetic tests (TOF) indicate a prior dissociation of the PPh3 molecule (or by its oxygenation) from I to yield pentacoordinated RuHCl(CO)(PPh3)2 which is almost as active as II.

Catalysis at the Interface of Ruthenium Carbene and Ruthenium Hydride Chemistry: Organometallic Aspects and Applications to Organic Synthesis

“…Studies in the groups of Marcieniec and Fischer have revealed that styrene reacts with vinylsilanes 58a in the pres- ence of ruthenium carbene complex 2 [69] or the ruthenium hydride complex [RuHCl(CO)(PPh 3 ) 3 ] (59) [70] to give the same cross-metathesis product 58b and ethylene (Scheme 15).…”

“…Cross-metathesis of styrene and vinylsilanes A mechanism for the ruthenium hydride-catalyzed reaction has been proposed (Scheme 16) [70] that involves insertion of the vinylsilane into the RuϪH bond of Q to give the σ-alkyl intermediate R, which undergoes β-silyl elimination to give the RuϪSi intermediate S. Ethylene is displaced by styrene, which inserts into the RuϪSi bond to give a new σ-alkyl intermediate T. β-Hydride elimination regenerates the catalytically active species Q and liberates the vinylsilane 58. Alternatively, catalysts containing RuϪSi bonds can be employed in this reaction; these catalysts give comparable results.…”

Cross-metathesis of vinylsilanes with olefins in the presence of Grubbs’ catalyst

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Abstract-Effective cross-metathesis of H 2 C C(H)SiR 3 , where SiR 3 =Si(OMe) 3 , Si(OEt) 3 , Si(OSiMe 3 ) 3 , with selected olefins in the presence of (PCy 3 ) 2 Cl 2 Ru( CHPh) (I) is described. Treatment of p-substituted styrenes, 1-alkenes and selected allyl derivatives H 2 C CHCH 2 R% (R%=SiMe 3 , Si(OEt) 3 , Ph, OPh) with an excess of H 2 C C(H)SiR 3 results in the formation of the respective cross-metathesis products with good yields and selectivities.

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“…2 The reaction, which resembles crossmetathesis, however, proceeds by a non-metallocarbene mechanism involving activation of C H and Si C bonds according to Scheme 1. 3 Unfortunately, the formation of some amounts of isomerization products cannot be avoided when using this method. 4 The development of well-defined, functional group tolerant ruthenium and molybdenum metathesis catalysts has opened new opportunities for applying metathesis in organic synthesis.…”

Functionalization of Vinylspherosilicates by Ruthenium‐Catalyzed Silylative Coupling Reactions

“…The mechanism of SC proved by Wakatsuki [8] and by us [9] proceeds by insertion of the vinylsilane into the M-H bond and a β-Si transfer to the metal with elimination of ethylene to generate M-Si species, which is followed by insertion of the alkene into the M-Si bond and a β-H transfer to the metal with elimination of the substituted vinylsilane (Scheme 2). The most synthetically effective results are given in ref.…”