Siliciumorganische verbindungen: LXXVIII. Reduktive silylierung von konjugierten trienen zu 1,6-disilyl-dienen

The reductive silylation of 1,3,5-hexatriene (I) with trimethylsilyl chloride and magnesium affords 74% disilylhexadienes, consisting of 8% 1,4-bis(trimethylsilyl)-2,5-hexadiene (II) and 92% 1,6-bis(trimethylsilyl)-2,4-hexadiene (III). The isomers IIIa, IIIb and IIIc can be separated via the Dieis—Alder adducts. Maleic anhydride reacts with IIIa and IIIb to give the bis[(trimethylsilyl)methyl] derivatives of 4-cyclohexene-1,2-dicar?ylic acid anhydride (IVa and IVb), whereas IIIc does not react with maleic anhydride. By a reductive silylation reaction 3-methyl-l,3,5-hexatriene (V) gives the 1,6-bis-silylated 2,4-hexadienes VIa and VIb, which with maleic anhydride give the adducts VIIa and VIIb.