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Solvent-Dependent Stereoselectivity in the Addition of p-CH3OC6H4OH to
 

Summary: Articles
Solvent-Dependent Stereoselectivity in the Addition of
p-CH3OC6H4OH to
(E)-1,2-Di-tert-butyl-1,2-dimesityldisilene. Evidence for
Rotation around the Si-Si Bond in the Zwitterionic
Intermediate
Yitzhak Apeloig* and Moshe Nakash
Department of Chemistry and the Lise Meitner-Minerva Center For Computational Quantum
Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel
Received August 11, 1997
The diastereoselectivity of the addition of p-CH3OC6H4OH to (E)-1,2-di-tert-butyl-1,2-
dimesityldisilene (2) in benzene and in THF is reported, and the mechanistic implications
of the results are discussed. In both benzene and in THF the stereochemistry of the products
is independent of the phenol concentration (in the range of phenol excess of 2-300 equiv).
The syn:anti product ratio is 90:10 in benzene and of 20:80 in THF, i.e., with stereochemical
preference opposite to that in benzene. The finding that the stereochemistry of the products
is independent of the phenol concentration indicates that in the second step of the addition
reaction intermolecular proton transfer (from a second molecule of phenol) does not occur.
Thus, the anti-addition product results from rotation around the Si-Si bond in the
zwitterionic intermediate followed by intramolecular proton transfer. The very different

  

Source: Apeloig, Yitzhak - Department of Chemistry, Technion, Israel Institute of Technology

 

Collections: Chemistry