Catalytic carbonyl Z-dienylation via multicomponent reductive coupling of acetylene to aldehydes and α-ketoesters mediated by hydrogen:: Carbonyl insertion into cationic rhodacyclopentadienes
Catalytic carbonyl Z-dienylation via multicomponent reductive coupling of acetylene to aldehydes and α-ketoesters mediated by hydrogen:: Carbonyl insertion into cationic rhodacyclopentadienes
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DOI：
10.1021/ja0664786
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发表时间：
2006-12-20
影响因子：
15
通讯作者：
Krische, Michael J.
中科院分区：
文献类型：
--
作者：
Kong, Jong Rock;Krische, Michael J.
醛或α-酮酯在阳离子Rh催化剂存在下，在常温常压下暴露于等体积的乙炔和氢气中，可得到羰基Z-丁二烯基化产物，该产物通过四个分子的多组分偶联而产生： 两个乙炔分子，一个邻近的二羰基化合物分子和一个元素氢分子。这些集体数据表明，一种催化机理涉及到通过乙炔氧化二聚得到的阳离子罗达环戊二烯中间体中的羰基插入。生成的氧杂环庚二烯通过正式的σ键歧化反应进行氢解裂解，得到的产物是羰基加成和阳离子Rh(I)，从而结束催化循环。研究了在α-酮酯-6杂碳硼酸盐存在下1，6-二炔14的加氢反应，提出了催化机理。这些多组分偶联首次使用乙炔气体，这是一种基本的化学原料，用于金属催化的还原C-−-C键的形成。
Exposure of aldehydes or α-ketoesters to equal volumes of acetylene and hydrogen gas at ambient temperature and pressure in the presence of cationic rhodium catalysts provides products of carbonylZ-butadienylation, which arise via multicomponent coupling offourmolecules: two molecules of acetylene, a molecule of vicinal dicarbonyl compound, and a molecule of elemental hydrogen. The collective data suggest a catalytic mechanism involving carbonyl insertion into a cationic rhodacyclopentadiene intermediate derived via oxidative dimerization of acetylene. Hydrogenolytic cleavage of the resulting oxarhodacycloheptadiene via formal σ-bond metathesis provides the product of carbonyl addition and cationic rhodium(I) to close the catalytic cycle. Studies involving the hydrogenation of 1,6-diyne14ain the presence of α-ketoester6acorroborate the proposed catalytic mechanism. These multicomponent couplings represent the first use of acetylene gas, a basic chemical feedstock, in metal-catalyzed reductive C−C bond formation.