We report the first asymmetric sulfa-Michael addition (SMA) reactions using chiral N-heterocycliccarbene (NHC) as a non-covalent organocatalyst. We demonstrate that a triazolium salt derived NHC functions as an excellent...
Enantioselective Synthesis of Substituted Indoles Through Zirconium(IV)-Catalyzed Friedel–Crafts Alkylation
作者:José Pedro、Gonzalo Blay、Isabel Fernández、Carlos Vila
DOI:10.1055/s-0032-1317161
日期:——
Abstract The chiral complex of (R)-3,3′-Br2-BINOL and zirconium tert-butoxide catalyzes the Friedel–Craftsalkylation of indoles with enones bearing an alkyl or fluorinated group at the β-position to give indoles having a side chain at the C3 position with a tertiary stereogenic center in good yields and with excellent enantioselectivities. The chiral complex of (R)-3,3′-Br2-BINOL and zirconium tert-butoxide
Metal‐bound water molecules have recently been recognized as a new facet of soft Lewis acid catalysis. Herein, a chiral palladium aqua complex was constructed that enables carbon–hydrogen bonds of indoles to be functionalized efficiently. We embraced a chiral 2,2′‐bipyridine as both ligand and hydrogen‐bond donor to configure a robust, yet highly Lewis acidic, chiral aqua complex in water. Whereas the
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 enantioselectiveFriedel–Craftsalkylation 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
A Dual-Catalysis Approach to Enantioselective [2 + 2] Photocycloadditions Using Visible Light
作者:Juana Du、Kazimer L. Skubi、Danielle M. Schultz、Tehshik P. Yoon
DOI:10.1126/science.1251511
日期:2014.4.25
Then a second—a chiral Lewis acid—catalyst directs the product stereochemistry. A major advantage of the dual reactions is that each catalyst can be tuned independently. A two-catalyst combination offers long-sought selectivity in intermolecular coupling of olefins to form four-membered rings. [Also see Perspective by Neier] In contrast to the wealth of catalytic systems that are available to control the