Cross-metathesis vs. silylative coupling of vinyl alkyl ethers with vinylsilanes catalyzed by a ruthenium–carbene complex (Grubbs catalyst)
作者:Bogdan Marciniec、Małgorzata Kujawa、Cezary Pietraszuk
DOI:10.1039/b003442h
日期:——
Grubbs
complex, (PCy3)2Cl2RuCHPh (I) is a very effective catalyst of the cross-disproportionation of vinyl-trisubstituted silanes H2CCHSiR3
[where R3=Me3, PhMe2, (OEt)3] with vinyl alkyl ethers H2CCHORâ²
[where Râ²=ethyl, propyl, butyl, t-butyl,
t-pentyl, 2-(ethyl)hexyl, cyclohexyl, trimethylsilyl] to yield a mixture of (E+Z) 1-silyl-2-alkoxyethenes. The
reaction occurs quantitatively under milder conditions (60°C) than the analogous one catalyzed by RuâH
and/or RuâSi complexes reported previously (80°C). The stoichiometric reaction of (I) and (PCy3)2Cl2RuCH2 (III) with vinyl
ethyl ether leads to the formation of (PCy3)2Cl2RuCH(OEt) (II), inactive in the stoichiometric reaction with vinylsilanes but very active in the catalytic process. Experiments with the use of deuterated vinylsilanes indicate the non-metallacarbene mechanism of the reaction and provide evidence for the initiation of RuâH bond formation
ia the
hydrovinylation with vinylsilanes.
Grubbs 复合物 (PCy3)2Cl2RuCHPh (I) 是乙烯基三取代硅烷 H2CCHSiR3 [其中 R3=Me3, PhMe2、(OEt)3] 与乙烯基烷基醚 H2CCHORâ² [其中 Râ²= 乙基、丙基、丁基、叔丁基、叔戊基、2-(乙基)己基、环己基、三甲基硅基]发生交叉歧化反应,生成 (E+Z) 1-硅基-2-烷氧基乙烯混合物。与之前报道的由 RuâH 和/或 RuâSi 复合物催化的类似反应(80°C)相比,该反应是在更温和的条件下(60°C)定量发生的。(I)和(PCy3)2Cl2RuCH2 (III)与乙烯基乙醚的化学计量反应会生成(PCy3)2Cl2RuCH(OEt) (II),在与乙烯基硅烷的化学计量反应中没有活性,但在催化过程中非常活跃。使用氚代乙烯基硅烷进行的实验表明了该反应的非金属碳化机制,并为 RuâH 键在与乙烯基硅烷的氢乙烯化反应中开始形成提供了证据。