Highly enantioselective Friedel–Crafts alkylation of indole with electron deficient trans-β-nitroalkenes using Zn(II)–oxazoline–imidazoline catalysts
摘要:
The catalytic asymmetric Friedel-Crafts alkylation of indole with trans-beta-nitroolefins has been developed via the catalysis of Zn(II)-oxazoline-imidazoline complexes. The reaction furnished nitroalkylated indoles in excellent yields (up to 95%) and with high enantioselectivities (up to 99% ee). The effects of solvent, temperature, the metal-triflate, and the ligand structure on the reaction are discussed. The substrates of the reaction can be substituted aromatic nitroolifins. The higher reactivity and enantioselectivity of the reaction could be due to the activation and asymmetric induction of chiral Lewis acids coordinated by the nitroolefin through a 1,3-metal bonded intermediate. (C) 2013 Elsevier Ltd. All rights reserved.
A Library of Chiral Imidazoline–Aminophenol Ligands: Discovery of an Efficient Reaction Sphere
作者:Takayoshi Arai、Naota Yokoyama、Akira Yanagisawa
DOI:10.1002/chem.200701439
日期:2008.2.27
ligands. Further reductive alkylation using salicylaldehydes 7-10 provided a series of imidazoline-aminophenol ligands (L9-L24). Analysis by solid-phase catalysis/circular dichroism high-throughput screening of a copper-catalyzed Henry reaction revealed that ligand L25, comprising a (S,S)-diphenylethylenediamine-derived imidazoline, (S)-phenylethylamine, and dibromophenol, was highly efficient, thus providing
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 Bis(oxazolidine)pyridine–Copper-Catalyzed Enantioselective Friedel–Crafts Alkylation of Indoles with Nitroalkenes
作者:Takayoshi Arai、Toru Sato
DOI:10.1055/s-0033-1340311
日期:——
asymmetric Friedel–Crafts reaction of indoles with nitroalkenes was catalyzed by the stereochemically tunable bis(oxazolidine)pyridine (PyBodine)–Cu(OTf)2 complex. Using the PyBodine(Val)–Cu(OTf)2 catalyst gave the Friedel–Crafts adducts with highly enantioselective manner. For the 1,4-bis[(E)-2-nitrovinyl]benzene, the reaction proceeded in a meso-trick manner to give the chiral double Friedel–Crafts adduct