NMR Spectroscopic Characterization and DFT Calculations of Zirconium(IV)-3,3′-Br<sub>2</sub>–BINOLate and Related Complexes Used in an Enantioselective Friedel–Crafts Alkylation of Indoles with α,β-Unsaturated Ketones
作者:Gonzalo Blay、Joan Cano、Luz Cardona、Isabel Fernández、M. Carmen Muñoz、José R. Pedro、Carlos Vila
DOI:10.1021/jo3013594
日期:2012.12.7
Experimental and theoretical studies on the structure of several complexes based on (R)-3,3′-Br2–BINOL ligand and group (IV) metals used as catalysts in an enantioselective Friedel–Crafts alkylation of indoles with α,β-unsaturated ketones have been carried out. NMR spectroscopic studies of these catalysts have been performed, which suggested that at room temperature the catalysts would form a monomeric
基于(R)-3,3'-Br 2 -BINOL配体和第(IV)族金属的几种配合物结构的实验和理论研究,用于对映体的α,β-不饱和吲哚的对映选择性Friedel-Crafts烷基化反应酮已被进行。已经对这些催化剂进行了NMR光谱研究,这表明在室温下,对于Ti IV,催化剂将形成单体结构,对于Zr IV和Hf IV,催化剂将形成二聚结构。密度泛函理论(DFT)的计算清楚地证实了这些实验光谱学研究的结论。具有双桥基序的二聚体结构[Zr IV 2(μ-(R)-3,3'-Br 2 -BINOL)2 ],其中每个联萘酚配体充当金属中心之间的桥(Novak模型)比带有双桥基序的二聚体结构[Zr IV 2(μ-O )更稳定t Bu)2 ],其中叔丁醇基团起桥连配体的作用(小林模型)。研究了Friedel-Crafts烷基化的吲哚结构。最后,提出了Friedel-Crafts反应的合理机理和催化剂作用方式的立