Conformational change in a urea catalyst induced by sodium cation and its effect on enantioselectivity of a Friedel-Crafts reaction
作者:Arjun K. Chittoory、Gayatri Kumari、Sudip Mohapatra、Partha P. Kundu、Tapas K. Maji、Chandrabhas Narayana、Sridhar Rajaram
DOI:10.1016/j.tet.2014.03.068
日期:2014.5
indeed in an unfavorable conformation. Infrared and Raman spectroscopic studies show that sodium binds the catalyst through the carbonyl and sulfonyl groups. Simulated IR and Raman spectra match well with the experimentally recorded spectra, thereby corroborating the proposed conformational change. This result shows that weak Lewis acids can be used to tune the conformation of hydrogen-bonding catalysts
Monodentate N-Ligand-Directed Bifunctional Transition-Metal Catalysis: Highly Enantioselective Friedel-Crafts Alkylation of Indoles with Nitroalkenes
作者:Fengfeng Guo、Guoyin Lai、Shunshun Xiong、Sujing Wang、Zhiyong Wang
DOI:10.1002/chem.201000540
日期:2010.6.11
A role beyond base: A highly efficient, asymmetric Friedel–Craftsalkylation of indoles with nitroalkenes is presented that uses simple nitrogen compounds combined with Schiff base zinc(II) complexes as bifunctional catalysts (see scheme). The nitrogen compounds here play a crucial role as ligands as well as their traditional role as bases.
Rhodium-Catalyzed Asymmetric Addition of Arylboronic Acids to Indolylnitroalkenes
作者:Junwei Xing、Guihua Chen、Peng Cao、Jian Liao
DOI:10.1002/ejoc.201101648
日期:2012.2
bioactive structures. Most approaches to access chiral indolylnitroethanes involve organocatalyzed or metal-catalyzed asymmetric FriedelCrafts reaction of indoles with nitroalkenes. We have developed an efficient approach to optically pure a-aryl-3-indolylnitroethanes through rhodium-catalyzed asymmetric 1,4-addition of arylboronicacids to indolylnitroalkenes. Excellent yields (up to 99?%) and enantiomeric
A New Type of Bis(sulfonamide)-Diamine Ligand for a Cu(OTf)<sub>2</sub>-Catalyzed Asymmetric Friedel–Crafts Alkylation Reaction of Indoles with Nitroalkenes
作者:Jing Wu、Xincheng Li、Fan Wu、Boshun Wan
DOI:10.1021/ol201914r
日期:2011.9.16
Chiral bis(sulfonamide)-diamine served as new type of ligand for a Cu(OTf)2-catalyzed asymmetricFriedel–Craftsalkylation reaction of indoles with nitroalkenes. The desired products were obtained with up to 99% yield and 97% ee.
Orthogonal Enantioselectivity Approaches Using Homogeneous and Heterogeneous Catalyst Systems: Friedel-Crafts Alkylation of Indole
作者:Hun Young Kim、Sungkyung Kim、Kyungsoo Oh
DOI:10.1002/anie.201001484
日期:2010.6.14
With or without support? The complementary homogeneous and heterogeneouscatalystsystems have been developed for the catalytic asymmetric Friedel–Craftsalkylation of indoles with nitroalkenes, in which either of the enantiomeric products 2 could be selectively obtained under the suitable reaction conditions (i.e. with or without an added solid support; see scheme).