Friedel-Crafts Alkylation Reaction Of Indoles Research Articles

Superhydrophobic MOF/polymer composite with hierarchical porosity for boosting catalytic performance in an humid environment.

The poor hydrostability of most reported metal-organic frameworks (MOFs) has become a daunting challenge in their practical applications. Recently, MOFs combined with multifunctional polymers can act as a functional platform and exhibit unique catalytic performance; they can not only inherit the outstanding properties of the two components but also offer unique synergistic effects. Herein, an original porous polymer-confined strategy has been developed to prepare a superhydrophobic MOF composite to significantly enhance its moisture or water resistance. The selective nucleation and growth of MOF nanocrystals confined in the pore of PDVB-vim are closely related to the structure-directing and coordination-modulating properties of PDVB-vim. The resultant MOF/PDVB-vim composite not only produces superior superhydrophobicity without significantly disturbing the original features but also exhibits a novel catalytic activity in the Friedel-Crafts alkylation reaction of indoles with trans-β-nitrostyrene because of the accessible sites and synergistic effects.

Asymmetric Ruthenium-Catalyzed Hydrogenation of Terpyridine-Type N-Heteroarenes: Direct Access to Chiral Tridentate Nitrogen Ligands.

The first enantioselective hydrogenation of terpyridine-type N-heteroarenes has been successfully developed by using Ru(diamine) complexes as catalysts, providing partially reduced chiral pyridine-amine-type products in high yield (up to 93%) with excellent diastereo- and enantioselectivity (up to 94:6 dl/meso, > 99% ee). These pyridine-amine-type compounds can be served as a new class of chiral multidentate nitrogen-donor ligands, which were successfully applied to the Cu-catalyzed asymmetric Friedel-Crafts alkylation reaction of indoles with nitroalkenes.

キラルブレンステッド酸触媒の創製と新展開

Development of efficient chiral catalyst continues to be an important challenge in the fields of synthetic organic chemistry and medicinal chemistry. Although metal-based Lewis acid catalysts had been extensively studied for the activation of carbonyl group and imine, chiral Brønsted acid has emerged in the beginning of 21st century. We synthesized chiral phosphoric acid, derived from (R)-BINOL, and demonstrated its catalytic activity in the Mannich-type reaction as a chiral Brønsted acid in 2004. Chiral phosphoric acid functioned as bifunctional catalyst bearing both basic site and Brønsted acidic site. The 3,3’-substituents play an important role. Since then, chiral phosphoric acid catalysis has become a popular research area, and its utility has been remarkably expanded. In this article, we will describe the development of chiral phosphoric acid and recent progress of the chiral phosphoric acid catalysis from our research group, in particular following topics; 1) transfer hydrogenation reaction of ketimines by use of benzothiazoline as a hydrogen donor, and oxidative kinetic resolution of indolines, 2) Friedel-Crafts alkylation reaction of indoles, and 3) enantioselective synthesis of chiral biaryls by bromination and transfer hydrogenation. In addition, several tips for using chiral phosphoric acid are also described.

Asymmetric Friedel–Crafts Alkylation of α-Substituted β-Nitroacrylates: Access to β2,2-Amino Acids Bearing Indolic All-Carbon Quaternary Stereocenters

A highly enantioselective Friedel-Crafts alkylation reaction of indoles with acyclic α-substituted β-nitroacrylates is developed under the catalysis of Ni(ClO4)2-bisoxazoline complex at 1 mol % catalyst loading, affording chiral indolic β-nitroesters bearing all-carbon quaternary stereocenters in excellent yields and ees of up to 97%. Transformation of one of the products to β(2,2)-amino ester and tetrahydro-β-carboline through nitro reduction and sequential Pictet-Spengler cyclization was exemplified.

Facile synthesis of 5H-benzo[b]carbazol-6-yl ketones via sequential reaction of Cu-catalyzed Friedel-Crafts alkylation, iodine-promoted cyclization, nucleophilic substitution and aromatization.

A convenient method to access 5H-benzo[b]carbazol-6-yl ketones via a sequential Cu-catalyzed Friedel-Crafts alkylation reaction of indoles with 2-(2-(alkynyl)benzylidene)malonates and iodine-promoted electrophilic cyclization followed by nucleophilic substitution and aromatization was developed. The products of the functional 5H-benzo[b]carbazol-6-yl ketones were obtained with up to 98% yield.

Cu(OTf)2-Catalyzed Asymmetric Friedel–Crafts Alkylation Reaction of Indoles with Arylidene Malonates Using Bis(sulfonamide)-Diamine Ligands

A highly efficient Cu-catalyzed asymmetric Friedel-Crafts alkylation reaction of indoles with arylidene malonates using simple, stable, and easily prepared bis-sulfonamide diamine ligands was developed. The desired products were obtained in up to 99% yield with 96% ee.

Highly Enantioselective Construction of Trifluoromethylated All-Carbon Quaternary Stereocenters via Nickel-Catalyzed Friedel–Crafts Alkylation Reaction

A highly enantioselective Friedel-Crafts alkylation reaction of indoles with β-CF(3)-β-disubstituted nitroalkenes was achieved using a Ni(ClO(4))(2)-bisoxazoline complex as a catalyst, which afforded indole-bearing chiral compounds with trifluoromethylated all-carbon quaternary stereocenters in good yields with excellent enantioselectivities (up to 97% ee). The transformation of one of the products into first a trifluoromethylated tryptamine and then a trifluoromethylated tetrahydro-β-carboline by sequential nitro reduction and Pictet-Spengler cyclization were realized with complete preservation of enantiopurity.

ChemInform Abstract: Synthesis of Functionalized Indoles with a Trifluoromethyl‐Substituted Stereogenic Tertiary Carbon Atom Through an Enantioselective Friedel—Crafts Alkylation with β‐Trifluoromethyl‐α,β‐enones.

Chiral complexes of BINOL-based ligands with zirconium tert-butoxide catalyze the Friedel-Crafts alkylation reaction of indoles with beta-trifluoromethyl-alpha,beta-unsaturated ketones to give functionalized indoles with an asymmetric tertiary carbon center attached to a trifluoromethyl group. The reaction can be applied to a large number of substituted alpha-trifluoromethyl enones and substituted indoles. The expected products were obtained with good yields and ees of up to 99%.

Synthesis of Functionalized Indoles with a Trifluoromethyl‐Substituted Stereogenic Tertiary Carbon Atom Through an Enantioselective Friedel–Crafts Alkylation with β‐Trifluoromethyl‐α,β‐enones

Chiral complexes of BINOL-based ligands with zirconium tert-butoxide catalyze the Friedel-Crafts alkylation reaction of indoles with beta-trifluoromethyl-alpha,beta-unsaturated ketones to give functionalized indoles with an asymmetric tertiary carbon center attached to a trifluoromethyl group. The reaction can be applied to a large number of substituted alpha-trifluoromethyl enones and substituted indoles. The expected products were obtained with good yields and ees of up to 99%.

Efficient Lewis acid-assisted Brønsted acid (LBA) catalysis in the iron-catalyzed Friedel-Crafts alkylation reaction of indoles

Abstract Lewis acid-assisted Brønsted acid (LBA) catalysis was proposed for the iron-catalyzed Friedel-Crafts alkylation of indoles with chalcones. This proposal was supported by the ESI-MS and cyclic voltammetry. The addition of acac to the iron-catalyzed Friedel-Crafts alkylation of indoles with chalcones created a powerful catalytic system, which makes the alkylation reactions occur easily under mild conditions.

The Role of the Indole in Important Organocatalytic Enantioselective Friedel-Crafts Alkylation Reactions

With the development of catalytic asymmetric methodologies directed to the synthesis of biologically active molecules during the last years, organocatalysis has emerged as a powerful tool. The organocatalytic approach is complementary to transition metal-based catalysis within the field of asymmetric synthesis and several research groups have achieved great aims in this area by the first time. The enantioselective Friedel-Crafts alkylation reaction of indoles is a powerful and direct method for preparing enantiomerically pure 3- or 2-substituted indolyl compounds and a number of organocatalyzed syntheses of these indolyl substrates have been developed in recent years. Due to the abundance of indole moieties in enantiomerically pure biologically interesting natural compounds asymmetric strategies have arisen as important processes of synthesis. These important alkylation processes including the addition of indole to α,β-unsaturated carbonyl compounds, nitroalkenes and imines as well as their applications will be discussed in this review.

Catalytic enantioselective addition of indoles to arylnitroalkenes: An effective route to enantiomerically enriched tryptamine precursors

A new valuable catalytic protocol for the preparation of synthetically useful beta-indolyl nitro compounds bearing benzhydryl stereocenters is presented. The combined use of catalytic amounts of a commercially available chiral [SalenAlCl] complex and pyridine allowed, for the Friedel-Crafts alkylation reaction of indoles with aromatic nitro-olefins to be carried out in good yields and enantioselectivity (up to 63% ee).