| Research Abstract |
In this paper we report the platinum-catalyzed reactions of isopmpy-substituted benzodisilacyclobutene. The reactions of 3, 4-benzo-1, 1, 2, 2-tetra(isopropy1)-l, 2-disi1acyclobut-3-ene (1) with phenylacetylene and 1-hexyne in the presence of a catalytic amount of (eta^2-ethylene)bis(tripheny1phosphine)platinum(O) at 200ﾟC for 24h gave two types of 1 : 1 ackiucts, 2-phenyl- and 2-butyl-substituted 5, 6-benzo-1 , 1 , 4, 4-tetra(isopropyl)- 1 , 4-disilacyclohexa-2, 5-diene and 2-benzylidene- and 2-pentylidene-substituted 4, 5-benzo- 1, 1 , 3, 3-tetra(isopropyl)-1, 3-disilacyclopent-4ene, respectively. With mesityl- and dimethylphenylsilylacetylene, 1 afforded 2-(mesityl)methylene- and 2-(dimethylphenylsilyl)- methylene4, 5-benzo-1, 1, 3 , 3-tetra(isopmpyl)-1 , 3disilacyclopent-4-ene. Similar reaction of i with trimethylsilyl-acetylene produced an adduict ansing from sp-hybridized C-H bond activation of the acetylene, together with a benzodisilacyclopentene derivative. The reaction of 1 w
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ith dephenylacetylene yielded a 2, 3-diphenyl-5, 6-benzodisilacyclohexa-2, 5-diene derivative, while with methyiphenylacetylene and 2-hexyne, 1 gave 2-benzylidene- and 2-butylidene-5, 6-benzo-1 , 4-cisilacyclohex-5-ene, along with the benzodisilacyclohexa-2, 5-diene deriivatives. Similar treatment of 1 with methyl(trimethylsilyl)acetylene produced a 5, 6-benzo-2-(trimethylsilyl)methylenedisilacyclohexene derivative.
We also report the synthesis and platinum- and palladium-catalyzed reactions of benzobis(disilacyclobutene). Benzo[1 , 2 : 4, 5]bis(1, 1 , 2, 2-tetraethyl-1 , 2-disilacyclobut-3-ene) (2) was synthesized by the reaction of1, 2, 4, 5-tetrabmmobenzene with magnesium in the presence of diethyifluorosilane in THF.The reaction of 1 with diphenylacetylene in the presence of a catalytic amount of (eta^2-ethylene)bis(triphenylphosphine)platinum(O) in relluxing benzene gave a 1 : 2-adduct, benzo[1 , 2 : 4, 5]bis(1, 1, 4, 4-tetraethyl -2, 3-diphenyl- 1 , 4-disilacyclohexa-2, 5-diene) in 91% yield. Similar platinum(O)-catalyzed reaction of 1 with 3-hexyne and acetylene in refluxing benzene afforded the respective 1 : 2-adducts, benzo[1 , 2 : 4, 5]bis(disilacyclohexadiene) derivatives in excellent yields. Benzobis(disilacyclobutene) 1 also reacted with diphenylacetylene, 3-hexyne, and acetylene in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium(O) to give the corresponding 1 : 2 adducts in excellent yields. Less
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