1997 Fiscal Year Final Research Report Summary
Synthesis of Stable Silaaromatic Compounds by Taking Advantage of Steric Protection
| Project/Area Number |
08454197
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Organic chemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
OKAZAKI Renji The University of Tokyo, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (70011567)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Aromaticity / Silanaphthalene / X-ray crystallography / Bond delocalization / ^<29>Si NMR |
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| Research Abstract |
Aromatic hydrocarbons such as benzene and naphthalene play a very important role in organic chemistry, but silaaromatic compounds where some of the skeletal carbons are replaced by silicon is very unstable and there has been no example isolation of such compounds. In this study, we have succeeded in the synthesis of the first example of a silaromatic compound, 1.e., 2-silanapthalene 1, by taking advantage of kinetic stabilization afforded by a sterically protecting group, 2,4,6-tris[bis (trimethylsilyl) methyl]phenyl (Tbt group). Reduction of dichlorinated tetrahydronapthalene followed by reaction with TbtLi, Bromination, reduction, and rebromination gave the direct precursor of 1. Debromination of 1 with t-BuLi in hexane gave 1 as colorless crystals. Although 1 reacts with water and oxygen very rapidly, it is thermally quite stable. The structure was established by ^1H and ^<29>Si NMR and X-ray crystallography. Of particular note is the ^<29>Si signal, which appear at delta 87.4, indicating the presence of sp_2 Si. Furthermore, the ^1J coupling constants of Cl-Si and Si-C3 are 92 and 76 Hz, respectively, clearly indicating that there is some delocalization of pi-electrons in the silanaphthalene ring. Another 2-silanaphthalene having 2,6-bis[bis(trimethylsilyl)methyl]-4-tris[(trimethylsilyl)methyl]phenyl group was also synthesized.
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