Physical properties
NMR studies have shown the reagent is monomeric in ether.
Uses
Dimethylphenylsilyllithium is widely used as reagent for addition to carbonyl compounds; deoxygenation
reactions; in presence of copper(I) salts, an effective reagent
for conjugate addition to α,β-unsaturated compounds, conjugate
displacement of tertiary allylic acetates, and silylcupration of
alkynes and allenes.
Preparation
Dimethylphenylsilyllithium is readily prepared from the reaction of
PhMe2SiCl with 2 equiv of Li metal in THF or from the
reaction of PhMe2SiSiMe2Ph with Li metal in THF. Typical reaction procedure involves stirring chlorodimethylphenylsilane with lithium in THF at 0°Cunder N2 for 4–36 h; the
chlorosilane is converted into tetramethyldiphenyldisilane in
the first 10 min, and the remainder of the time is needed to
cleave the disilane. The supernatant reagent solution is
calibrated using standard methods and used without further purification for reactions. It is sometimes advantageous to
activate the Li metal prior to use by ultrasound irradiation of
a hexane suspension, and to use argon as the inert gas to
prevent formation of lithium nitrides.
