Abstract
Facile methods for the introduction of alkenyl and alkynyl groups at the bridgehead position of polysilamodule HC(SiMe2 SiMe2 )3 CH are established. Deprotonation of the module with BuLi/t -BuOK in THF at -40 °C followed by alkylation with bromoacetaldehyde diethyl acetal gives the corresponding acetal, which was hydrolyzed with zinc chloride, yielding a formylmethyl-substituted cage compound. Treatment of the aldehyde with triflic anhydride in the presence of 2,6-di-t -butyl-3-methylpyridine produced the corresponding enol triflate consisting of a 4:1 mixture of E and Z isomers. Palladium-catalyzed cross-coupling of the triflate with organometallic reagents afforded alkenyl group-substituted cage molecules in good yields. Meanwhile, lithiation of phenylthio-substituted cage derivative with lithium 4,4′-di-tert -butylbiphenylide in THF followed by transmetalation with copper iodide and subsequent coupling with iodoalkynes allowed us to prepare alkynyl-substituted polysilacage compounds. The structures were determined by X-ray diffraction of single crystals.
Key words
silicon - cage compounds - bicyclo[2.2.2]octane - alkenyl - alkynyl
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