The oxidation can also be performed in the presence of a free
hydroxyl group. However :
* The free hydroxyl function interfered with the course of the sila-Pummerer rearrangement.
* This can be circumvented using :
- the oxidation of the thioether function to the corresponding sulfone 8 .
- the sulfone can then be subjected directly to the Tamao oxidation, affording the desired diol 10 in good yield, along with the cyclopropylsulfone 9 (Scheme 5).
This approach provides an extension to the concept illustrated in scheme 1 and shows that oxidations of DMPTCS do not require the protection of alcohol functions present on the substrate.
A further illustration that phenylsulfonylcyclopropyl is an excellent nucleofugal group on silicon  is provided by the sequence shown in Scheme 6.
The silane 12 was reacted with the alpha-diazoester 11 in the presence of Rh2(OAc)4 to give 13 . Reduction of the ester function with LiAlH4 gave the unstable ß-hydroxysilane which was directly oxidized using the same conditions as above to afford the diol 14 in reasonable overall yield.
Polyhydroxylated silanes can also be obtained through Sharpless dihydroxylation . For example, allylsilane 15 affords the desired diol which was purified as its acetonide 16. This latter is then oxidized as described above to afford the triol acetonide 17  in 70% yield (Scheme 7).
The C-Si bond oxidation can therefore be carried out equally well through the sulfoxide or the sulfone route, and in both cases in high yields.