Silanes Silyl substituted arenes

Reactions at acid centers to create 5 -2-(trimethylsilyl) ethanethiolesters are also common. Carboxylic 5-thiolesters are formed in high yield by the DCC/DMAP mediated coupling of 2-(trimethylsilyl)ethanethiol and carboxylic acids or by thiol substitution on a carboxylic acid chloride. 5 -2-(Tiimethylsilyl) ethyl p-toluenethiolsulfonate is formed by treating 2-(trimethyl-silyl)ethanethiol with tosyl bromide (eq 4). The product is a useful electrophile for carbon nucleophiles, allowing the introduction of the 2-(trimethylsilyl)ethylthio unit by an alternative mechanism. Independent of the thiol, aryl and alkyl 2-trimethylsilylethyl thioethers may be prepared by the radical addition of the appropriate arene- or aikanethiol to vinyl trimethyl-silane in a reaction comparable to that of eq l7 ... 

The last example conveys a noteworthy message. Aryl-attached silyl groups are latent hydroxyl functions as they may be oxidized like halo-, alkoxy-, or dialkylamino-substituted silanes and unlike heteroatom-free tetraalkylsilanes. As a matter of fact, arylsilanes are prone to any kind of electrophilic attack. Thus, acids split them into the arene and a silanol and aqueous tetrafluoroboric acid into a fluorosilane. Both are oxidizable of course. 

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