Treatment of triphenylbismuth difluoride with alkenyltrimethylsilanes 1 or trimethylsilyl cyanide–alkenyltrialkylstannanes 3 in the presence of boron trifluoride–diethyl ether gave the corresponding alkenyltriphenylbismuthonium 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 transferered both the vinyl and phenyl moieties to these nucleophiles to afford the sulfones 7–10 or the sulfides 12, 13, respectively. In the presence of a palladium catalyst, the salt 2e underwent the Heck-type reaction with ethyl acrylate 17 to afford the dienoate 18 and cinnamate 19 in moderate yields. Action of KOBut on the salt 2b yielded p-tolylacetylene 22, while a similar reaction with the salt 2e in the presence of the styrenes 23 gave the cyclopropanes 24. A Hammett study of the latter reaction has suggested a possible involvement of an alkylidenecarbene as the intermediate in these base-promoted reactions.
三苯基二
氟化
铋与烯基三甲基
硅烷1或三甲基
硅氰基-烯基三烷基
锡烷3在
三氟化硼-
乙醚存在下反应,以中等至良好收率得到相应的烯基
三苯基铋鎓四
氟硼酸盐2。盐2e的X射线晶体学分析证实了中心
铋原子扭曲的四面体几何结构。当与亚砜5或
硫醇盐11处理时,盐2容易将
乙烯基和苯基部分转移到这些亲核试剂上,分别得到砜7-10或
硫化物12、13。在
钯催化剂的存在下,盐2e与
丙烯酸乙酯17发生 Heck 型反应,以中等收率得到二烯酸酯18和
肉桂酸酯19。KOBut 对盐2b的作用产生了对甲
苯乙炔22,而在
苯乙烯23的存在下,盐2e的类似反应得到了
环丙烷24。后一反应的 Hammett 研究表明,这些碱促进的反应中可能涉及一个烯基碳烯中间体。