Silaheterocyclen IX. Darstellung und Charakterisierung von 2,4-Dineopentyl-1,3-disilacyclobutanen

Article abstract of DOI:10.1016/0022-328X(90)87197-L

The E/Z-isomers of 2,4-dineopentyl-1,3-disilacyclobutanes (R¹R²SiCHCH2^tBu)2 are obtained in good yields from the reaction of diorganovinylchlorosilanes R¹R²Si(Cl)CH=CH2 with Li^tBu in non-polar solvents.This synthetic route becomes less attractive as the number of chlorosubstituents at the vinylsilane increases: Thus, tetrachloro-2,4-dineopentyl-1,3-disilacyclobutane (2) cannot be prepared from Cl3SiCH=CH2 (1) and Li^tBu in a preparative scale.Addition of a twice-molar amount of NEt3 to the mixture of 1/Li^tBu results in the formation of this basic disilacyclobutane as the sole reaction product in nearly quantitative yield.Evidently the bis-donor stabilized neopentylsilene (Et3N)2<*>Cl2Si=CHCH2^tBu (δ), whose reactivity is comparable for this clean reaction.These experimental findings are in good agreement with the cycloaddition behaviour of δ.Careful refunctionalization of the tetrakissubstituted disilacyclobutane 6 with gaseous HCl at low temperature is an alternative route to 2, which can be transformed into the H-, F- and organo-substituted derivatives by substitution reactions.However, the preparation of disilacyclobutanes of the type by selective replacement of the chloroatoms failed.These compounds can be obtained from the reaction of the corresponding vinylchlorosilanes with Li^tBu in the presence of NEt3 as the Lewis base in good yields.