阳离子钨氧-亚烷基-N-杂环卡宾配合物：高活性烯烃复分解催化剂。
Cationic tungsten-oxo-alkylidene-N-heterocyclic carbene complexes: highly active olefin metathesis catalysts.
机构信息
§Institute of Polymer Chemistry and ‡Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
出版信息
J Am Chem Soc. 2015 May 20;137(19):6188-91. doi: 10.1021/jacs.5b03788. Epub 2015 May 7.
The synthesis, structure, and olefin metathesis activity of the first neutral and cationic W-oxo-alkylidene-N-heterocyclic carbene (NHC) catalysts are reported. Neutral W-oxo-alkylidene-NHC catalysts can be prepared in up to 90% isolated yield. Depending on the ligands used, they possess either an octahedral (Oh) or trigonal bipyramidal ligand sphere. They can be activated with excess AlCl3 to form cationic olefin metathesis-active W-complexes; however, these readily convert into neutral chloro-complexes. Well-defined, stable cationic species can be prepared by stoichiometric substitution of one chloro ligand in the parent, neutral W-oxo-alkylidene-NHC complexes with Ag(MeCN)2B(Ar(F))4 or NaB(Ar(F))4; B(Ar(F))4 = B(3,5-(CF3)2-C6H3)4. They are highly active olefin metathesis catalysts, allowing for turnover numbers up to 10,000 in various olefin metathesis reactions including alkenes bearing nitrile, sec-amine, and thioether groups.
本文报道了首例中性和阳离子 W-氧代-亚烷基-N-杂环卡宾（NHC）催化剂的合成、结构和烯烃复分解活性。中性 W-氧代-亚烷基-NHC 催化剂的最高产率可达 90%。根据所使用的配体，它们具有八面体（Oh）或三角双锥配位球体。它们可以用过量的 AlCl3 激活，形成阳离子烯烃复分解活性 W-配合物；然而，这些配合物容易转化为中性氯配合物。通过在母体中性 W-氧代-亚烷基-NHC 配合物中用 Ag(MeCN)2B(Ar(F))4 或 NaB(Ar(F))4（B(Ar(F))4=B(3,5-(CF3)2-C6H3)4）取代一个氯配体，可以制备出稳定的、定义明确的阳离子物种。它们是高活性的烯烃复分解催化剂，在各种烯烃复分解反应中，包括含有腈、仲胺和硫醚基团的烯烃，其周转数高达 10,000。
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