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
A heterotrimetallic Pd–Sm–Pd complex for asymmetric Friedel–Crafts alkylations of pyrroles with nitroalkenes
作者:Guoqi Zhang
DOI:10.1039/c2ob25074h
日期:——
Catalytic asymmetric FriedelâCrafts alkylations of pyrroles and nitroalkenes were carried out by using a novel heterotrimetallic PdâSmâPd catalyst based on a simple chiral ligand 1, to give the adducts with high yields and up to 93% ee.
Asymmetric Friedel–Crafts reaction of N-heterocycles and nitroalkenes catalyzed by imidazoline–aminophenol–Cu complex
作者:Naota Yokoyama、Takayoshi Arai
DOI:10.1039/b904275j
日期:——
Catalytic asymmetric FriedelâCrafts reaction of pyrrole with nitroalkenes was smoothly catalyzed by newly synthesized nitro-substituted imidazolineâaminophenol (1b)âCu complex to give the adduct with up to 92% ee.
Chiral Bro̷nsted Acid-Catalyzed Asymmetric Friedel−Crafts Alkylation of Pyrroles with Nitroolefins
作者:Yi-Fei Sheng、Qing Gu、An-Jiang Zhang、Shu-Li You
DOI:10.1021/jo9013029
日期:2009.9.4
A highly efficient Friedel-Crafts reaction of pyrroles with nitroolefins by a chiral phosphoric acid was realized. With 5 mol % of catalyst, reactions conducted at rt afforded the 2-substituted or 2,5-disubstituted pyrroles in up to 94% ee for a wide range of substrates.
Asymmetric Friedel−Crafts Alkylation of Pyrroles with Nitroalkenes Using a Dinuclear Zinc Catalyst
作者:Barry M. Trost、Christoph Müller
DOI:10.1021/ja711080y
日期:2008.2.1
The catalytic enantioselective and atom economic Friedel-Crafts alkylation of pyrroles with nitroalkenes under mild reaction conditions using a dinuclear zinc catalyst is reported. The versatility of the reaction is demonstrated by the conversion of a number of differentially substituted nitroalkenes with differentially substituted pyrroles. Tandem addition reactions to form 2,5-disubstituted pyrroles are also demsonstrated. All pyrrole alkylations have been carried out without using N-protecting groups, which also enhances the efficiency by which substituted pyrroles may be synthesized. The reactions result in good yields and excellent enantioselectivities.