Sakurai reaction special

The addition reaction of alcohols to silenes is a strictly regiospecific process the OR group in the product is always attached to the silicon. The reaction is of special importance since silenes are easily trapped by reagents like methanol and t-butanol, and isolation of the adducts is normally taken as evidence for an intermediate silene. Furthermore, the alcohol addition to silenes is the prototypical reaction for the 1,2-addition of polar bonds across the Si=C double bond. A complete account on the alcohol addition to silenes, including the most recent mechanistic implications, is given in the chapter by Sakurai. We will therefore give only a brief survey of the reactivity of several families of silenes towards alcohols. 

Oxiranes of terminal monosubstituted and internal disubstituted olefins do not undergo the isomerization under standard conditions, but give aldehydes at elevated temperature. For the special substrates described in Sch. 35, different modes of reaction originated from intermediary carbocationic species, involve neighboring functional group participation, oxidation, etc. An improvement employing other silicon Lewis acids, for example Mc3SiI and McsSiBr, was developed by Kraus, Detty, and Sakurai [17,19f,62]. 

In 1975, Kumada and co-workers and Sakurai and co-workers reported that in the presence of a catalytic amount of palladium complexes, disilanes of the type Me Si2Xg (n = 1-6 X = H and F) or 1,2-disilacycloaIkanes add to various acetylenic compounds to give double silylation products. Nagai and co-workers developed the reaction and found that the double silylation of acetylenic compounds occurs not only with disilanes of special substituents but also with other common disilanes such as methoxymethylsilanes and hexamethyldisilane (Scheme 3). 

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