| Autor: |
Tahara, Atsushi, Nagino, Shunsuke, Sunada, Yusuke, Haige, Ryohei, Nagashima, Hideo |
| Zdroj: |
Organometallics; July 2018, Vol. 37 Issue: 15 p2531-2543, 13p |
| Abstrakt: |
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·CHCl3and 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 1by Pd(0) species, was involved in the reaction mechanism. The DFT calculations suggest that oxidative addition of Si–Si bonds in 1to Pd(CNAd)2species is followed by extrusion of a Me2Si═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 1to generate (SiMe2)5, which also contributes to formation of 3and (SiMe2)4by the Pd(0)-catalyzed reaction with an alkyne. Extrusion of Me2Si═Pd(CNAd) and ring contraction generated more than five Me2Si: species from (SiMe2)6(1). |
| Databáze: |
Supplemental Index |
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