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Protonation of Phenyl(trimethylsilyl)acetylene: A Surprisingly Weak Stabilization of a Carbocation by a β‐Trimethylsilyl Group
Author(s) -
Kresge A. Jerry,
Tobin John B.
Publication year - 1993
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199307211
Subject(s) - carbocation , trimethylsilyl , phenylacetylene , protonation , chemistry , silylation , hyperconjugation , acetylene , medicinal chemistry , group (periodic table) , photochemistry , computational chemistry , organic chemistry , catalysis , molecule , ion
The protodesilylation of the title compound 1 [Eq. (a)] proceeds via the vinyl cation 2 , whose stabilization by the β‐trimethylsilyl group is much smaller than expected. The comparison of the rate of protonation of 1 and that of phenylacetylene gives a small β‐silyl stabilizing effect (ΔΔ G † = 3.4 kcal mol −1 ). This surprising result is explained by insufficient hyperconjugation.