Ruthenium-catalyzed propargylic substitution reactions of propargylic alcohols with oxygen-, nitrogen-, and phosphorus-centered nucleophiles.
Ruthenium-catalyzed propargylic substitution reactions of propargylic alcohols with oxygen-, nitrogen-, and phosphorus-centered nucleophiles.
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DOI：
10.1002/chem.200400833
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发表时间：
2005-02
期刊：
影响因子：
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通讯作者：
Y. Nishibayashi;M. Milton;Youichi Inada;M. Yoshikawa;I. Wakiji;M. Hidai;S. Uemura
中科院分区：
文献类型：
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作者：
Y. Nishibayashi;M. Milton;Youichi Inada;M. Yoshikawa;I. Wakiji;M. Hidai;S. Uemura
介绍了铼催化炔丙醇与杂原子中心亲核试剂的炔丙基取代反应的研究范围和局限性。氧、氮和磷为中心的亲核试剂如醇、胺、酰胺和氧化膦可用于该催化反应。只有硫醇根桥联的双钌配合物才能作为该反应的催化剂。一些化学计量反应和催化反应的结果表明，催化炔丙基取代反应是通过原位形成的亚丙二烯络合物进行的，其中亲核试剂对亚丙二烯C（γ）原子的攻击是关键步骤。对炔丙醇与几种对位取代苯胺反应的相对速率常数的研究表明，苯胺对丙二烯叉基C（γ）原子的进攻不参与反应的速率控制步骤，而是由苯胺进攻C（γ）原子后形成的炔基络合物的共轭苯胺的酸性决定的，被认为是决定该催化反应速率的最重要因素。通过使用硫醇根桥联的二钌配合物促进该催化反应的关键点被认为是在催化循环中二钌配合物上的亚乙烯基配体与另一个炔丙醇之间的配体交换步骤的容易性。在该催化反应中，只有硫醇根桥联的双钌配合物相对于其它单钌配合物更容易促进配体交换步骤的原因应该是一个Ru部分（其不参与丙二烯叉基形成）作为电子池或移动的配体作用于另一个Ru位点。这里提出的催化过程提供了一个通用的，直接的，和一个步骤的方法，炔丙醇的炔丙基取代的对比，到目前为止，众所周知的化学计量和逐步尼古拉斯反应。
The scope and limitations of the ruthenium-catalyzed propargylic substitution reaction of propargylic alcohols with heteroatom-centered nucleophiles are presented. Oxygen-, nitrogen-, and phosphorus-centered nucleophiles such as alcohols, amines, amides, and phosphine oxide are available for this catalytic reaction. Only the thiolate-bridged diruthenium complexes can work as catalysts for this reaction. Results of some stoichiometric and catalytic reactions indicate that the catalytic propargylic substitution reaction proceeds via an allenylidene complex formed in situ, whereby the attack of nucleophiles to the allenylidene C(gamma) atom is a key step. Investigation of the relative rate constants for the reaction of propargylic alcohols with several para-substituted anilines reveals that the attack of anilines on the allenylidene C(gamma) atom is not involved in the rate-determining step and rather the acidity of conjugated anilines of an alkynyl complex, which is formed after the attack of aniline on the C(gamma) atom, is considered to be the most important factor to determine the rate of this catalytic reaction. The key point to promote this catalytic reaction by using the thiolate-bridged diruthenium complexes is considered to be the ease of the ligand exchange step between a vinylidene ligand on the diruthenium complexes and another propargylic alcohol in the catalytic cycle. The reason why only the thiolate-bridged diruthenium complexes promote the ligand exchange step more easily with respect to other monoruthenium complexes in this catalytic reaction should be that one Ru moiety, which is not involved in the allenylidene formation, works as an electron pool or a mobile ligand to another Ru site. The catalytic procedure presented here provides a versatile, direct, and one-step method for propargylic substitution of propargylic alcohols in contrast to the so far well-known stoichiometric and stepwise Nicholas reaction.