1ST ISOLATION OF 6-MEMBERED CYCLIC ACETYLENE - SYNTHESIS AND REACTION OF TETRASILACYCLOHEXYNES

Six-membered cyclic acetylenes, namely 1,1,2,2,3,3,4,4-octaalkyl-1,2,3,4-tetrasilacyclohexynes (1), have been synthesized directly by the reaction of 1,4-dichlorooctaalkyltetrasilanes with acetylene di-Grignard reagent followed by GC purification. It is found that the tetrasilacyclohexyne 1a is thermally stable: t1/2 = 8 h (decane, 174-degrees-C). Reactions of 1a with dicobalt octacarbonyl, 2,3-dimethyl-1,3-butadiene, phenyl azide, and diphenyldiazomethane give the corresponding cyclo-adducts, respectively.