PLATINUM-CATALYZED REACTIONS OF 3,4-BENZO-1,1,2,2-TETRAETHYL-1,2-DISILACYCLOBUT-3-ENE

Treatment of 3,4-benzo-1,1,2,2-tetraethyl-1,2-disilacyclobutene (1) with a catalytic amount of (eta2-ethylene)bis(triphenylphosphine)platinum(0) in refluxing benzene gave 1-(diethylphe-nylsilyl)-2-(diethylsilyl)benzene (2) and cis-4,5-benzo-1,1,3-triethyl-2-methyl-1,3-disilacyclopent-4-ene (3) in 10 % and 67 % yields. The platinum-catalyzed reaction of 1 with ethylene produced 5,6-benzo-1,1,4,4-tetraethyl-1,4-disilacyclohex-5-ene, while with styrene and 1-hexene, compound 1 afforded 4,5-benzo-1,3-disilacyclopent-4-ene derivatives. A similar reaction of 1 with a-methylstyrene produced an adduct arising from hydrosilylation of 3 to alpha-methylstyrene. The reaction of 1 with phenylacetylene, diphenylacetylene, phenyl(trimethylsilyl)acetylene, and 3-hexyne in the presence of a platinum catalyst yielded the respective 5,6-benzo-1,4-. disilacyclohexa-2,5-dienes. With benzaldehyde, 1 gave a 5,6-benzo-2-oxa-1,4-disilacyclohex-5-ene derivative.