Takeda Takeshi, Kuroi Shuichi, Ozaki Makoto, Tsubouchi Akira
Department of Applied Chemistry, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
Org Lett. 2004 Sep 2;6(18):3207-10. doi: 10.1021/ol0486066.
[reaction: see text] The Cp(2)TiP(OEt)(3)-promoted reaction of 2-(alk-1-yn-1-yl)-2-(trialkylsilyl)-1,3-dithianes with 1-alkenes regioselectively produced [(trialkylsilyl)ethynyl]cyclopropanes with a formal allylic rearrangement. The reaction of the thioacetals with ketones proceeded with the same regioselectivity to produce 1-(trialkylsilyl)alk-3-en-1-ynes predominantly. It is suggested that these reactions proceed via the formation of titanium alpha-(silylethynyl)carbene complexes Cp(2)Ti=C(R)CCSi in preference to their regioisomers, alpha-silylalkynylcarbene complexes Cp(2)Ti=C(Si)CCR.
[反应：见正文] 在Cp(2)TiP(OEt)(3)促进下，2-(链-1-炔-1-基)-2-(三烷基甲硅烷基)-1,3-二硫杂环己烷与1-烯烃的反应区域选择性地生成具有形式上烯丙基重排的[(三烷基甲硅烷基)乙炔基]环丙烷。硫代缩醛与酮的反应以相同的区域选择性进行，主要生成1-(三烷基甲硅烷基)链-3-烯-1-炔。有人认为，这些反应优先通过形成钛α-(甲硅烷基乙炔基)卡宾配合物Cp(2)Ti=C(R)CCSi而不是其区域异构体α-甲硅烷基炔基卡宾配合物Cp(2)Ti=C(Si)CCR来进行。
