共查询到20条相似文献,搜索用时 0 毫秒
1.
Complexes of BINOL-based ligands with Zr(OtBu)4 catalyze the Friedel-Crafts alkylation reaction of indoles and pyrrole with nonchelating beta-substituted alpha,beta-enones at room temperature affording the expected products with good yields and ee above 95% in most of the studied examples. 相似文献
2.
Palomo C Oiarbide M Kardak BG García JM Linden A 《Journal of the American Chemical Society》2005,127(12):4154-4155
Remarkably high and regular enantioselectivities are obtained in Friedel-Crafts alkylation reactions involving alpha'-hydroxy enone templates and Cu(II)-bis(oxazoline) complexes as catalysts. The simple elaboration of adducts provides a route to enantioenriched aldehydes, carboxylic acids, and ketones containing the pyrrole and indole frameworks. 相似文献
3.
A procedure for the enantioselective alkylation of indole at the 2-position with simple non-chelating enones is described for the first time. Reaction between 4,7-dihydroindole and enones in the presence of zirconium(IV)-BINOL complexes, followed by a p-benzoquinone oxidation gives indoles alkylated at the 2-position with good yields and moderate enantioselectivities. 相似文献
4.
[reaction: see text] The Friedel-Crafts reaction is an important reaction for the formation of new C-C bonds. Recently, catalytic enantioselective Friedel-Crafts reaction of alkylidene malonates has been reported. However, the substituents in alkylidene malonates are limited. To explore new substituents such as carboxyl and carbonyl groups, catalytic enantioselective Friedel-Crafts reactions of reactive ethenetricarboxylates and acyl-substituted methylenemalonates 1 were investigated. The reaction of 1 with indoles in the presence of catalytic amounts of chiral bisoxazoline copper(II) complex (10%) in THF at room temperature gave alkylated products in high yields and up to 95% ee. The enantioselectivity can be explained by the secondary orbital interaction on approach of indole to the less hindered side of the 1-Cu(II)-ligand complex. 相似文献
5.
6.
The use of an equimolar amount of pyrrolidine and HClO4 (30 mol%) was found to be effective in promoting the conjugate addition of indoles to (E)-alpha,beta-unsaturated ketones, affording the corresponding beta-indolyl ketones in excellent yields. 相似文献
7.
An operationally simple and entirely green protocol for heteropoly acid (10 mg) catalyst conjugate addition of indoles and pyrrole to unsaturated carbonyl compounds and nitroalkene in water at ambient temperature in good to excellent yields has been developed. 相似文献
8.
[reaction: see text] A novel asymmetric Friedel-Crafts alkylation of indoles with nitroalkenes catalyzed by Zn(II)-bisoxazoline complexes has been developed. The nitroalkylated indoles are synthesized in excellent yields and high enantioselectivities (up to 90% ee). The effects of ligand structure, metal salt, and solvent on the reaction are discussed. The substrates of the reaction can be aromatic, heteroaromatic, and even aliphatic nitroalkenes. The high reactivity and selectivity of the reaction are presumptively attributed to the activation and asymmetric induction of chiral Lewis acids coordinated by nitroalkene substrates through a 1,3-metal bonding model. 相似文献
9.
Catalytic enantioselective radical conjugate addition reactions using alpha'-phosphoric enone templates have been studied. The C 2-symmetric bisoxazoline-zinc(II) complex proves to be effective for high enantioselectivities and chemical yields. In addition, intermediate alpha-carbonyl alkyl radicals could be trapped with allyltributylstannane to afford anti-isomers as major products with high enantioselectivities. 相似文献
10.
11.
An organocatalytic Friedel-Crafts alkylation of indoles with α,β-unsaturated ketones was found to be efficiently accelerated under high-pressure conditions with a low loading of chiral primary amine salts with good yield and enantioselectivity up to 90%. This approach also allows, for the first time, selected indole derivatives containing quaternary stereogenic centers to be obtained from prochiral β,β-disubstituted enones with an enantioselectivity up to 80%. 相似文献
12.
A new class of chiral phosphoric acids with spirobiindane as scaffold were conveniently synthesized from (S)-1,1'-spirobiindane-7,7'-diol ((S)-SPINOL) and employed to catalyze the asymmetric Friedel-Crafts reaction of indoles with imines to afford 3-indolyl methanamines. High yields (68-97%) and excellent enantioselectivities (up to 99% ee) were obtained. 相似文献
13.
Substituted indole scaffolds are often utilized in medicinal chemistry as they regularly possess significant pharmacological activity. Therefore the development of simple, inexpensive and efficient methods for alkylating the indole heterocycle continues to be an active research area. Reported are reactions of trichloroacetimidate electrophiles and indoles to address the challenges of accessing alkyl decorated indole structures. These alkylations perform best when either the indole or the imidate is functionalized with electron withdrawing groups to avoid polyalkylation. 相似文献
14.
15.
[reaction: see text] Enantioselective additions of pyrroles to alpha,beta-unsaturated 2-acyl imidazoles catalyzed by the bis(oxazolinyl)pyridine-scandium(III) triflate complex (1) have been accomplished. The alpha,beta-unsaturated 2-acyl imidazoles were synthesized in high yields through Wittig olefination. A short, enantioselective synthesis of the alkaloid (+)-heliotridane has been accomplished utilizing this methodology and a 2-acyl imidazole cleavage and cyclization. This methodology was then extended to the one-pot asymmetric synthesis of 2-substituted indoles. 相似文献
16.
A method for Cu-catalyzed asymmetric conjugate addition (ACA) of dialkylzinc reagents to tetrasubstituted five- and six-membered cyclic enones that afford quaternary all-carbon stereogenic centers in up to 95% ee is reported. Catalytic ACAs are practical and efficient. Reactions proceed to >98% conversion in undistilled commercial grade toluene in the presence of 2 mol % of an air-stable Cu salt (CuCN) and a readily available chiral ligand. Enantioselective ACA reactions deliver products that can be readily functionalized to afford a variety of synthetically versatile compounds in high optical purity. 相似文献
17.
The alkylation of indole and 2-methylindole with alkyl halides in the presence of a complex catalyst — dipyridinezinc chloride — was investigated. Nitromethane was used as the solvent. 3-Alkylindoles were obtained in 30–80% yields in all cases. The reaction mechanism is discussed. Data from the PMR and mass spectra are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 921–924, July, 1978. 相似文献
18.
[Structure: see text] Highly enantioselective Friedel-Crafts alkylation of simple and aromatic ethers (4a-l) with 3,3,3-trifluoropyruvate (3) was accomplished by using chiral (4R,5S)-DiPh-BOX(1b)-Cu(OTf)2 complex (1 mol %) as a catalyst under solvent-free conditions. Excellent yields and enantioselectivities (90-93% ee, after recrystallization up to 99% ee) of the Friedel-Crafts alkylation products were obtained. 相似文献
19.
Rare earth halides supported on mineral supports (K10 montmorillonite and silica) were investigated as catalysts for Friedel-Crafts alkylations. This project concerns the replacement of the widely used Lewis acid AlCl3 in Friedel-Crafts reactions by environmentally friendly catalysts in that they circumvent the production of aluminum waste. The catalytic activity of these heterogeneous catalysts was established in a series of alkylations of aromatic compounds. 相似文献