SILICON CARBON UNSATURATED-COMPOUNDS .35. THERMOLYSIS OF 3,4-BENZO-1,1,2,2-TETRAETHYLDISILACYCLOBUTENE

Thermolysis of 3,4-benzo-1,1,2,2-tetraethyl-1,2-disilacyclobutene (1) at 250-degrees-C gave 4,5,7,8-dibenzo-1,1,2,2,3,3,6,6-octaethyl-1,2,3,6-tetrasilacycloocta-4,7-diene (4). Similar thermolysis of 1 with tert-butyl alcohol produced 1-(tert-butoxydiethylsilyl)-2-tau(diethylsilyl)benzene. The reaction of compound 1 with phenylacetylene, 1-hexyne, and dimethyl acetylenedicarboxylate afforded the respective [4 + 21 cycloadducts arising from o-quinodisilane and the acetylenes. Similarly, heating 1 with benzaldehyde and formaldehyde yielded the corresponding [4 + 2] cycloadducts, while with methyl vinyl ketone 1 gave an eight-membered cyclic compound, 7,8-benzo-1,1,6,6-tetraethyl-3-methyl-2-oxa-1,6-disilacycloocta-3,7-diene.