Figure 5 - available from: Research on Chemical Intermediates
This content is subject to copyright. Terms and conditions apply.
Source publication
Indole derivatives have attracted significant attention in organic synthesis and bioactivity research owing to their substantial biological activity. In the present study, several 3-naphthylindole analogues were synthesized by direct arylation of 1-diazonaphthalene-2-(1H)-ones by rhodium(II)-catalyzed cross-coupling reaction and their antioxidant a...
Similar publications
Essential oils are mixtures of potent compounds with biological effects, such as those with antioxidant, antimicrobial, antitumor and/or anti-inflammatory effects. In this paper, the antioxidant and antimicrobial activity of essential oils of different types of commercial pepper was tested. Essential oils are prepared by hydrodistillation. Polyphen...
Ducrosia anethifolia (D. anethifolia) is a drought-tolerant plant widely distributed over Arar valley at the Northern region of Saudi Arabia. The aerial parts of this plant were investigated for its phytochemical constituents, antioxidant and antibacterial potential. GC-MS analysis of the ethyl acetate fraction of methanol extract revealed the pres...
Objective: In this study it was aimed to examine antiquorum sensing, antioxidant activities by using root and aerial parts extracts of Tragopogon oligolepis. Also phenolic content was detected using HPLC analysis.Material-Method: Antioxidant activity was detected by DPPH, FRAP methods and phenolic content HPLC. Antiquorum sensing activity was inves...
Today, the use of essential oils is increasing day by day, and it is considered as raw materials in many industries. Therefore, this study aims to identify the essential oil profile, antioxidant and antimicrobial activity of Rosa canina L. and Rosa pimpinellifolia L. reveal their potential use in the industry. Essential oils that were obtained in 2...
Araucaria angustifolia var. angustifolia and Araucaria angustifolia var. indehiscens, seeds (common pinhão and monkey pinhão) are consumed after cooking, coats and water represent waste. In this work, pinhão was submitted to different cooking conditions, the water extracts were analyzed to determine and identify their phenolic compounds content, an...
Citations
... They are broadly present as core structural components in bioactive natural products, organic functional materials and pesticides [1][2][3][4] . As one of the prominent subclass, axially chiral 3-arylindole and its derivatives are valuable candidates used to derive bioactive molecules [5][6][7][8] and chiral catalysts [Scheme 1A] [9] . In line with the progression of axial chirality chemistry, the design and synthesis of axially chiral 3-arylindole frameworks have also emerged Scheme 1. ...
The direct enantioselective construction of axially chiral 3-arylindole frameworks via nucleophilic addition of 2-substituted indoles to iminoquinones has been achieved with high efficiencies under mild chiral phosphoric acid (CPA) catalytic conditions. The utility of this method was demonstrated in successful scale-up syntheses without compromising the product yields and enantioselectivities. The oxidation of products yields axially chiral heteroaryl-p-quinone monoimine, which could be subjected to structural diversification via addition of nucleophiles.
A highly enantio- and diastereoselective dynamic kinetic resolution (DKR) of configurationally labile 3-aryl indole-2-carbaldehydes is described. The DKR proceeds via a Rh-catalyzed intermolecular asymmetric reductive aldol reaction with acrylate esters, with simultaneous generation of three stereogenic elements. The strategy relies on the labilization of the stereogenic axis that takes place thanks to a transient Lewis acid–base interaction (LABI) between the formyl group and a thioether moiety strategically located at the ortho′ position. The atropisomeric indole products present a high degree of functionalization and can be further converted to a series of axially chiral derivatives, thereby expanding their potential application in drug discovery and asymmetric catalysis.
A mild method for an efficient synthesis of C3-naphthyl indoles from o-alkynylacetophenones has been developed. This Ag-catalyzed transformation is assisted by the acetal formed under the reaction condition employing trimethyl...
The first chiral phosphoric acid (CPA) catalyzed cycloaddition-elimination cascade reaction of 2-naphthol- and phenol-derived enecarbamates with azonaphthalenes has been established, providing a highly atroposelective route to an array of axially chiral aryl-C3-benzoindoles in excellent yields with excellent enantioselectivities. The success of this strategy derives from the stepwise process involving CPA-catalyzed asymmetric formal [3 + 2] cycloaddition and subsequent central-to-axial chirality conversion by elimination of a carbamate. In addition, the practicality of this reaction had been verified by varieties of transformations towards functionalized atropisomers.
The past two decades have witnessed unprecedented development and advancement of chiral phosphoric acid catalysis. Therefore, it is not surprising that the attempts to synthesize enantioenriched axially chiral compounds via chiral phosphoric acid catalysis have achieved fruitful results in recent years although this area of research is still in its infancy. A number of structurally important heterocycles with chiral atropisomerism have been successfully designed and prepared by chiral phosphoric acid promoted transformations involving diverse strategies: including direct coupling, de novo formation of a heterocyclic ring and functionalization of prochiral or racemic substrates. In this minireview, we would like to highlight the advances in the field of atropisomeric heterocycles construction enabled by chiral phosphoric acid catalysis. In addition, this Minireview is organized based on the different types of atropisomeric heterocyclic frameworks generated covering quinoline, pyrrole, indole, benzimidazole, quinazolinone, isoindolinone, urazole, pyrazole and so on. We hope that this Minireview will motivate continuous interest on chiral phosphoric acid catalyzed atroposelective reactions.
A chemoselective dearomatization of the less reactive benzenoid unit in β-naphthol was developed. Spirocyclization with a reductant constructs a pivotal structure for drug candidates. One-pot oxidative conversion enabled the tandem dearomatization of β-naphthol, producing conjugated tetraenone variants. The potential utility of the product as an F--selective anion sensor was also demonstrated. Theoretical studies revealed the intermediacy of silver-carbenoid species leading to chemoselective spirocyclization over arene cyclopropanation.
A catalytic asymmetric synthesis of 3,3’-bisindoles bearing single axial chirality has been established via chiral phosphoric acid (CPA) catalyzed enantioselective addition reaction of 3,3’-bisindoles with ninhydrin-derived 3-indolylmethanols. The selection of ninhydrin-derived 3-indolylmethanols as suitable electrophiles is based on the consideration that the symmetric and bulky moiety of ninhydrin would increase the steric congestion around the axis to generate stable axial chirality and avoid the generation of central chirality. By this approach, a series of 3,3’-bisindoles bearing single axial chirality were synthesized via dynamic kinetic resolution (DKR) process in generally acceptable yields and considerable enantioselectivities. In addition, an in-depth investigation on the property (stability and rotation barrier) of the synthesized axially chiral 3,3’-bisindoles were carried out, thus providing useful information for this class of axially chiral frameworks. This approach makes use of the strategy of dynamic kinetic resolution of 3,3’-bisindoles, therefore expanding the generality and applicability of this strategy for catalytic asymmetric synthesis of 3,3’-bisindoles bearing single axial chirality.
A copper-catalyzed direct asymmetric coupling of C2 sterically-hindering-group-substituted indoles with quinone and naphthoquinone esters was developed by using the spirocyclic pyrrolidine oxazoline (SPDO) ligand, which was accomplished by metal catalysis for the first time. Diverse structures of axially chiral 3-arylindoles were obtained with good to high enantioselectivities in good to high yields. This protocol can be expanded to implement β-coupling with naphthoquinone esters, providing an alternative way to prepare β-substituted derivatives of both naphthols and naphthoquinones.
of main observation and conclusion
An atroposelective synthesis of a new class of 3,3’‐bisindoles bearing axial and central chirality has been established via catalytic asymmetric addition reactions using isatin‐derived imines as electrophiles (23 examples, up to 80% yield, >95:5 dr, 98:2 er). This approach takes advantage of chiral phosphoric acid‐catalyzed dynamic kinetic resolution of 2‐substituted 3,3’‐bisindoles via the nucleophilic addition of such substrates with isatin‐derived imines. In this approach, isatin‐derived imines acted as a class of competent electrophiles due to their high reactivity and bulky size, which provided an easy access to axially chiral 3,3'‐bisindoles incorporated with a biologically important chiral 3‐aminooxindole unit. This approach has greatly expanded the generality and applicability of the strategy of dynamic kinetic resolution of 2‐substituted 3,3’‐bisindoles for the synthesis of enantioenriched 3,3’‐bisindole derivatives bearing both axial and central chirality.
This article is protected by copyright. All rights reserved.
