No abstract

The reaction of trichloro(viny1)silane (1) and LitBu (2) initially 7-9 to give the [4 + 21 cycloaddition compounds 10-12.leads to the a-lithio adduct C13SiCH(Li)CH2tBu (3) which can These Diels-Alder products are thermally unstable and decombe trapped by trimethylsilyl triflate yielding the C-silylated pose slowly at room temperature into the starting furans and product [C13SiCH(SiMe3)

1994organo-silicon compounds, nonmetal heterocycles organo-silicon compounds, nonmetal heterocycles S 0067 -205Silaheterocycles.Part 26. Facile Synthesis of Silicon Dichloro Substituted 3-Vinyl-1-silacyclobutanes from Silene/Butadiene (2 + 2) Cycloaddition Reactions: Model Compounds for Vinylsilacyclobutane . fwdarw. Silacyclohexene Rearrangements.-The reaction between the in situ formed silene (III) and various 1,3-butadienes, leading almost exclusively to monosilacyclobutanes, represents a facile synthesis for these products, which are useful building blocks for the preparation of new Si-containing materials. They also serve as models for mechanistic studies. The reaction between (III) and the dienes does not proceed stereospecifically. On thermolysis the E isomers of the 3-vinylsilacyclobutanes undergo ring expansion to the (4 + 2) cycloadducts, while the Z isomers undergo retro "ene" reactions affording allylvinylsilanes via ring cleavage. Appropriate substituents of a cycloadduct as for example (XVII)/(XVIII) disfavor the latter reaction and lead to the unexpected formation of nearly only (94%) the Diels-Alder products, containing (XIX) as the major derivative together with the three other possible isomers (79:5: 5:5). -(SEWALD, N.; ZICHE, W.; WOLFF, A.; AUNER, N.; Organometallics 12 (1993) 10, 4123-4134; Anorg.-Chem.

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