FIRST SYNTHESIS, X-RAY STRUCTURE-ANALYSIS AND REACTIONS OF ALKENYLTRIPHENYLBISMUTHONIUM SALTS

Treatment of triphenylbismuth difluoride with alkenyltrimethylsilanes 1 or trimethylsilyl cyanide-alkenyltrialkylstannanes 3 in the presence of boron trifluoride-diethyl ether gave the corresponding alkenyltrip henylbismuthonium tetrafluoroborates 2 in moderate to good yields, An X-ray crystallographic analysis of the salt 2e confirmed the distorted tetrahedral geometry of the central bismuth atom, When treated with a sulfinate 5 or the thiolate 11, the salts 2 readily transferred both the vinyl and phenyl moieties to these nucleophiles to afford the sulf ones 7-10 or the sulfides 12, 13, respectively, In the presence of a p alladium catalyst, the salt 2e underwent the Heck-type reaction with e thyl acrylate 17 to afford the dienoate 18 and cinnamate 19 in moderat e yields, Action of KOBu(t) on the salt 2b yielded p-tolylacetylene 22 , while a similar reaction with the salt 2e in the presence of the sty renes 23 gave the cyclopropanes 24, A Hammett study of the latter reac tion has suggested a possible involvement of an alkylidenecarbene as t he intermediate in these base-promoted reactions.