Syntheses of Substituted 1,4-Disila-2,5-cyclohexadienes from Cyclic Hexasilane Si6Me12 and Alkynes via Successive Si-Si Bond Activation by Pd/Isocyanide Catalysts

Atsushi Tahara, Shunsuke Nagino, Yusuke Sunada, Ryohei Haige, Hideo Nagashima

Research output: Contribution to journalArticle

Abstract

Palladium-catalyzed reactions of dodecamethylcyclohexasilane [(SiMe2)6] (1) with alkynes led to efficient preparation of 1,1,4,4-tetramethyl-1,4-disilacyclohexadienes (3). The reactions were best catalyzed by Pd(0) species generated from Pd2(dba)3·CHCl3 and 1-isocyanoadamantane (AdNC). Terminal and internal alkynes bearing aryl and alkyl substituents could be used as substrates, and the reaction allowed gram-scale preparation of 3. A dimethylsilylene (Me2Si:) species, generated by activation of Si-Si bonds in 1 by Pd(0) species, was involved in the reaction mechanism. The DFT calculations suggest that oxidative addition of Si-Si bonds in 1 to Pd(CNAd)2 species is followed by extrusion of a Me2Siâ•Pd(CNAd) intermediate. Reaction of the resulting palladium-coordinated silylene with an alkyne forms a silacyclopropene, which dimerizes to give 3. The extrusion is accompanied by ring contraction of 1 to generate (SiMe2)5, which also contributes to formation of 3 and (SiMe2)4 by the Pd(0)-catalyzed reaction with an alkyne. Extrusion of Me2Siâ•Pd(CNAd) and ring contraction generated more than five Me2Si: species from (SiMe2)6 (1).

Original languageEnglish
Pages (from-to)2531-2543
Number of pages13
JournalOrganometallics
Volume37
Issue number15
DOIs
Publication statusPublished - Aug 13 2018

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Cyclohexenes
Alkynes
Cyanides
alkynes
Chemical activation
activation
Extrusion
catalysts
Catalysts
Palladium
synthesis
Bearings (structural)
contraction
palladium
Discrete Fourier transforms
preparation
rings
Substrates

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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Syntheses of Substituted 1,4-Disila-2,5-cyclohexadienes from Cyclic Hexasilane Si6Me12 and Alkynes via Successive Si-Si Bond Activation by Pd/Isocyanide Catalysts. / Tahara, Atsushi; Nagino, Shunsuke; Sunada, Yusuke; Haige, Ryohei; Nagashima, Hideo.

In: Organometallics, Vol. 37, No. 15, 13.08.2018, p. 2531-2543.

Research output: Contribution to journalArticle

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abstract = "Palladium-catalyzed reactions of dodecamethylcyclohexasilane [(SiMe2)6] (1) with alkynes led to efficient preparation of 1,1,4,4-tetramethyl-1,4-disilacyclohexadienes (3). The reactions were best catalyzed by Pd(0) species generated from Pd2(dba)3·CHCl3 and 1-isocyanoadamantane (AdNC). Terminal and internal alkynes bearing aryl and alkyl substituents could be used as substrates, and the reaction allowed gram-scale preparation of 3. A dimethylsilylene (Me2Si:) species, generated by activation of Si-Si bonds in 1 by Pd(0) species, was involved in the reaction mechanism. The DFT calculations suggest that oxidative addition of Si-Si bonds in 1 to Pd(CNAd)2 species is followed by extrusion of a Me2Si{\^a}•Pd(CNAd) intermediate. Reaction of the resulting palladium-coordinated silylene with an alkyne forms a silacyclopropene, which dimerizes to give 3. The extrusion is accompanied by ring contraction of 1 to generate (SiMe2)5, which also contributes to formation of 3 and (SiMe2)4 by the Pd(0)-catalyzed reaction with an alkyne. Extrusion of Me2Si{\^a}•Pd(CNAd) and ring contraction generated more than five Me2Si: species from (SiMe2)6 (1).",
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