Title

13C NMR Spectroscopic Study of 2-[1-(trimethylsilyl)vinyl]-2-adamantyl Cation, the First -silyl-substituted Carbocation

Abstract

2-[1-(Trimethylsilyl)vinyl]-2-adamantyl cation (2) was prepared by the ionization of 2-[1-(trimethylsilyl)vinyl]-2-adamantanol in FSO3H/SO2CF at -130°C and was characterized by 13C NMR spectroscopy. For comparison, the 2-vinyl-2-adamantyl cation (4) was similarly prepared and characterized. The cationic center of 2 is deshielded by 11.5 ppm over that of 4, indicating no β-silyl stabilization effect (either inductive or hyperconjugative). However, the low barrier for rotation across the C2-C1′ bond in 2 indeed supports the intermediate perpendicular cation being stabilized by β-silyl effect. The results are rationalized by MM2, ab initio, and IGLO calculations.

Department(s)

Chemistry

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1992 American Chemical Society (ACS), All rights reserved.


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