Diastereoselective synthesis monosubstituted allylic

Monosubstituted diene systems have been employed for the synthesis of bicyclic systems as well as monocyclics [17]. The simplest way to accomplish this is to construct a second ring onto an existing structure (Eq. 54). This cyclization process is initiated at the alkene lacking allylic substitution. The formation of the six-membered ring necessitates the use of methylphenylsilane as the silylat-ing reagent. Because the silane itself comprises a new stereocenter, it must be removed by oxidation to assess accurately the diastereoselectivity of cyclization. Fluxionality of the five-membered ring results in a mixture of diastereomers at the silylmethyl-substituted stereo center. 

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