Application to benzyl and allylsilanes
To test the viability of our
methodology, we prepared the benzylsilane 4a
and allylsilane 4b and submitted them to
metallation conditions using Schlosser's superbase .
Alkylation and allylations of 4a occurred smoothly to afford
5a-b in good yields (Scheme 2).
As expected, the regioselectivity during the alkylation of
allylsilane 4b is electrophile dependent  (Scheme 3).
Oxidation of the C-Si bondOxidation of 5
to sulfoxides using NaIO4 in MeOH-H2O, followed by thermal
rearrangement in benzene (or toluene for 5e) under reflux,
afforded the corresponding siloxanes in quantitative yields. These were
then subjected to Tamao oxidation  to give the expected alcohols 6a-e.
* The three step oxidation sequence can be carried out
without purification of any of the intermediates.
* An allylic double bond is not affected by the reaction conditions, allowing a mild conversion of an allylsilane (i.e. 5d) into the corresponding allylic alcohol (i.e. 6d)
* An aldehyde function can also be obtained from the corresponding vinylsilane (i.e. 6e).
* The PhMe2Si group is not affected by the oxidative conditions (i.e. 6e) (Scheme 4).