Tris- and Tetrakis(lithiomethyl)silanes: An Easy Access to New Building Blocks for Organosilicon Compounds
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- 作者：Carsten Strohmann ; Silke Lü ; dtke ; and Oliver Ulbrich
- 刊名：Organometallics
- 出版年：2000
- 出版时间：October 16, 2000
- 年：2000
- 卷：19
- 期：21
- 页码：4223 - 4227
- 全文大小：120K
- 年卷期：v.19,no.21(October 16, 2000)
- ISSN：1520-6041
文摘
Tris(lithiomethyl)silanes, RSi(CH2Li)3, and tetrakis(lithiomethyl)silane, Si(CH2Li)4, wereprepared by the reductive C-S bond cleavage with lithium p,p'-di-tert-butylbiphenylide(LiDBB) and characterized by trapping with Bu3SnCl. The yields of the isolated trappingproducts were 42-81% (>95% NMR yield of the crude product), indicating a high-yieldsynthesis of the corresponding poly(lithiomethyl)silane building blocks. Tetrakis(lithiomethyl)silane is the first compound containing four lithioalkyl groups without any stabilizationof the metalated carbon atoms by 
-systems. Tetrakis(lithiomethyl)silane was used for thesynthesis of 2,2,3,3,7,7,8,8-octamethyl-2,3,5,7,8-pentasilaspiro[4,6]nonane (10), a new spirocyclic disilane. The single-crystal X-ray diffraction study of 10 indicates two five-memberedrings in envelope conformation with ecliptically arranged methyl groups connected to a spirocompound by a central silicon atom. DFT geometry optimizations [B3LYP/6-31G(d) level]and NMR calculations (GIAO method, HF/6-31+G(d,p) level) of 10 confirm the observedconformation of 10 as an energetic minimum and support the experimental results.
-systems. Tetrakis(lithiomethyl)silane was used for thesynthesis of 2,2,3,3,7,7,8,8-octamethyl-2,3,5,7,8-pentasilaspiro[4,6]nonane (10), a new spirocyclic disilane. The single-crystal X-ray diffraction study of 10 indicates two five-memberedrings in envelope conformation with ecliptically arranged methyl groups connected to a spirocompound by a central silicon atom. DFT geometry optimizations [B3LYP/6-31G(d) level]and NMR calculations (GIAO method, HF/6-31+G(d,p) level) of 10 confirm the observedconformation of 10 as an energetic minimum and support the experimental results.