Building up strain in one step: synthesis of an edge-fused double silacyclobutene from an extensively trichlorosilylated butadiene dianion

  • The exhaustive trichlorosilylation of hexachloro-1,3-butadiene was achieved in one step by using a mixture of Si2Cl6 and [nBu4N]Cl (7:2 equiv) as the silylation reagent. The corresponding butadiene dianion salt [nBu4N]2[1] was isolated in 36 % yield after recrystallization. The negative charges of [1]2− are mainly delocalized across its two carbanionic (Cl3Si)2C termini (α-effect of silicon) such that the central bond possesses largely C=C double-bond character. Upon treatment with 4 equiv of HCl, [1]2− is converted into neutral 1,2,3,4-tetrakis(trichlorosilyl)but-2-ene, 3. The Cl− acceptor AlCl3, induces a twofold ring-closure reaction of [1]2− to form a six-membered bicycle 4 in which two silacyclobutene rings are fused along a shared C=C double bond (84 %). Compound 4, which was structurally characterized by X-ray crystallography, undergoes partial ring opening to a monocyclic silacyclobutene 2 in the presence of HCl, but is thermally stable up to at least 180 °C.

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Author:Isabelle Georg, Markus Bursch, Julius B. Stückrath, Edith Alig, Michael BolteORCiD, Hans-Wolfram LernerGND, Stefan Grimme, Matthias Wagner
Parent Title (English):Angewandte Chemie
Place of publication:Weinheim
Document Type:Article
Date of Publication (online):2020/06/02
Date of first Publication:2020/06/02
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2022/03/08
Tag:Carbanions; Cyclization; Heterocycles; Silacyclobutenes; Silylation
Page Number:7
First Page:16181
Last Page:16187
The authors are grateful to the Evonik Resource Efficiency GmbH, Rheinfelden (Germany), for the generous donation of Si2Cl6. I.G. wishes to thank the Evonik Foundation for a Ph.D. grant. This work was partially funded by the Bundesministerium für Wirtschaft und Energie through the WIPANO grant number 03THW10K19. The German Research Foundation (DFG) is gratefully acknowledged for financial support through a Gottfried Wilhelm Leibniz prize to S.G.
Institutes:Biochemie, Chemie und Pharmazie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Licence (German):License LogoCreative Commons - Namensnennung-Nicht kommerziell - Keine Bearbeitung 4.0