Dearomatization of normal paraffin by adsorption process using synthesized NaX zeolite

Linear alkyl benzenes （LABs） are the main materials for detergent production. The presence of aromatic compounds in this material can decrease the quality of the final product and enhance the deactivation rate of catalysts. In this research we used zeolite NaX for de-aromatization of the recycled paraffin from the alkylation unit of an LAB production complex. The effect of different parameters on the removal efficiency of adsorbent was studied and optimized. To study the re-usability of the adsorbent, the breakthrough curves were obtained by using a fixed bed column filled with the adsorbent. The results indicated that the adsorbent capacity remained unchanged after three regeneration cycles. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. It was concluded that the Langmuir model agreed well with the experimental data. The calculated thermodynamic parameters of the adsorption showed that the adsorption process was spontaneous and exothermic. The reaction rate was estimated by the pseudo-second order kinetic model.

Sustainable electrochemical dearomatization for the synthesis of diverse 2,3-functionalized indolines

Herein,we achieved a green and efficient dearomatization for the synthesis of 2,3-functionalized polycyclic indolines in an electrochemical way.This avoiding of external oxidants and metals approach allowed various nucleophilic sources(Nu¼anilines,TMSN3 and ROH)to perform the products,representing an environmentally benign means.Additionally,the continuous flow electrosynthesis and synthetic transformations also reveal the strong practicality of electrochemistry in organic synthesis.

Metal-free nucleophilic 7,8-dearomatization of quinolines:Spiroannulation of aminoquinoline protected amino acids

Atom-and step-economy in IBX assisted diversity-oriented synthesis is achieved with a versatile AQ auxiliary α-amino acid analogs offering rapid access to polycyclic spiro-quinolines featuring a quaternary stereocenter in 20%–91% yields under mild conditions via 7,8-dearomatization of quinolines. Free of a preinstalled activation group is highlight of this intramolecular oxidation spiroannulation tandem reaction. This type of N-heterospirocycles, traditionally difficult to access, may open the door to a potentially interest scaffold for synthetic and medicinal chemistry.

Br■nsted acid-catalyzed asymmetric dearomatization of indolyl ynamides: Practical and enantioselective synthesis of polycyclic indolines

Catalytic asymmetric dearomatization of indoles and alkynes has received much attention in the past decade because this strategy offers an attractive and alternative way for the efficient synthesis of valuable chiral polycyclic indolines. However, these reactions have been mostly limited to transition-metal catalysts, and the related chiral Br■nsted acid catalysis has been scarcely reported. Herein, we disclose a chiral phosphoric acid-catalyzed asymmetric dearomatization of indolyl ynamides by direct activation of alkynes. This metal-free method enables the practical and atom-economical construction of an array of valuable chiral polycyclic indolines in moderate to good yields with high enantioselectivities.

Asymmetric Dearomatization of Electron-Deficient Heteroarenes by a Phosphine-Catalyzed[3+2]Annulation with Vinylcyclopropanes

Asymmetric dearomatization reactions of various electron-deficient heteroarenes,including benzofurans,benzothiophenes,and indoles,have been described.Through a phosphine-catalyzed[3+2]annulation with vinylcyclopropanes,readily available heteroarene feedstocks undergo smooth dearomatization reactions,delivering a diverse array of valuable chiral cyclopentabenzodihydrofuran and cyclopentaindoline scaffolds in a highly diastero-and enantioselective manner.Notably,the employment of cyclopropanes in phosphine-mediated annulation for the dearomatization of electron-deficient arenes is unknown.

Construction of highly congested quaternary carbon centers by NHC catalysis through dearomatization

A NHC-catalyzed hypervalent iodine reagents and transition-metal free redox-neutral dearomatization of phenols is reported.This protocol provides an efficient access for highly congested quaternatry carbon centers construction.It also features operationally simplicity,mild reaction conditions and good functional group tolerance.Moreover,the reported procedure can be easily emplified to 1 g scale.Mechanism study reveals the dearomative transformation possibly undergoes a single electron transfer process with NHC radical cation as a reactive intermediate.

Asymmetric Fluorinative Dearomatization of Tryptophol Derivatives by Chiral Anion Phase-Transfer Catalysis

An asymmetric fluorinative dearomatization reaction of tryptophol derivatives was developed via chiral anion phase-transfer catalysis. Vari- ous fluorinated furoindolines were obtained in moderate to excellent yields and enantioselectivity in the presence of Selectfluor. The preliminary mecha- nistic studies suggested the existence of an in situ formed tryptophol boronic ester plays a critical role in determining the enantioselectivity. This method features the facile introduction of a fluorine atom in a highly enantioselective manner and construction of two contiguous quaternary stereogenic cen- ters.

Copper-Catalyzed Oxidative Dearomatization of 2-Naphthols via Etherification

Copper-catalyzed intermolecular oxidative-etherification type dearomatization reaction of 2-naphthols was developed.With air as the terminal oxidant,the reaction proceeded in excellent yields under mild conditions.In addition,the reaction between two different naphthol substrates occurred smoothly.A series of multifunctionalized β-naphthalenones,important scaffold existed widely in natural products and biologically active molecules,were synthesized efficiently.

Palladium-catalyzed diarylative dearomatization of indoles with aryl thioesters

We report herein a palladium-catalyzed diarylative dearomatization of indole by employing thioester and arylboronic acid as the aryl electrophiles.The reaction involved a decarbonylation/migratory insertion/terminal Suzuki coupling procedure.Substrates bearing various functional groups are well tolerated in the reaction,affording the diarylated indoline skeletons in moderate to good yields.

Diastereoselective 2,3-diazidation of indoles via copper(Ⅱ)-catalyzed dearomatization

The copper-catalyzed directed dearomatization of indoles with the assistance of directing groups has been developed for the synthesis of 2,3-diazido indolines with good yields and excellent diastereoselectivities in aqueous solution.The resultant 2,3-diazides can be smoothly converted to other functional groups,including vicinal diamines,triazoles and benzotriazoles,in a single step.

A tandem asymmetric oxidation-oxa-Michael sequence for dearomatization ofβ-naphthols

A catalytic asymmetric hydroxylative dearomatization reaction has been disclosed,and the products can smoothly transform into spiroannulation adducts by simply treated with a base under mild conditions.Novel in-situ generated magnesium catalytic methods are developed by application of combinational ligands.Related concise transformaitons of the spiroannulation adducts have been carried out.

Catalytic asymmetric brominative dearomatization reaction of benzofurans

A catalytic asymmetric brominative dearomatization reaction of benzofuran derivatives was achieved by using hydroquinidine 1,4-phthalazinediyl diether [（DHQ）_2PHAL] as the catalyst and N-bromoacetamide（NBAc） as the brominating reagent. A series of brominated spiro[benzofuran-2,5＇-oxazoles] bearing two contiguous stereogenic centers were obtained in high yields（up to 99%） with excellent enantioselectivity（up to 97% ee）.

Electrochemical Oxidation Dearomatization of Anisol Derivatives toward Spiropyrrolidines and Spirolactones

Spiro compounds are widely prevalent in biological activities and natural products.However,developing new strategies for their efficient synthesis and derivatization remains a challenge.Outstanding progress has been made in the synthesis of spiro compounds through dearomatization of aromatic compounds,most of them are mediated by the hypervalent iodine reagents.Herein,we report a method of anodic oxidation spiroamination and spirolactonization of anisole derivatives with concomitant cathodic reduction of protons in the absence of hypervalent iodine reagents.A wide variety of spiropyrrolidines and spirolactones with diverse functional groups made useful scaffolds in this transformation,with yields up to 97%.Moreover,hectogram-scale synthesis could supply target product with 83% yield in a flow electrochemical cell using carbon paper as the anode and nickel plate as the cathode,demonstrating the potential application of this method.

Catalytic Asymmetric[4+1]Spiroannulation ofα-Bromo-βNaphthols with Azoalkenes by an Electrophilic Dearomatization/S_(RN)1-Debromination Approach

An enantioselective[4+1]spiroannulation ofαbromo-β-naphthols with azoalkenes has been developed for the one-step construction of a new class of pyrazoline-based spirocyclic molecules.Using chiral Cu(II)/Box catalysts,asymmetric induction was achieved with high levels of enantioselectivity[up to 99:1 enantiomeric ratio(er)].Notably,α-chloroandα-iodo-substitutedβ-naphthols were also tolerated by this reaction.Mechanistic studies disclosed that this process was triggered by electrophilefacilitated dearomatization ofα-bromo-β-naphthols and followed by the debromination via SRN 1-subsitution with in situ-formed N-nucleophile.The chiral copper(II)-species,bound with azoalkene moiety,was assumed to control the enantiodiscrimination over the naphthoxy C-radical that was generated from the debromination step.Moreover,the potential utility of this protocol was greatly amplified by the derivatization of spirocyclic products through oxidative dearomatization of the other aromatic ring in the naphthyl fragment,providing a rather attractive route for the rapid generation of synthetically more valuable doubly dearomatized architectures.

Palladium-Catalyzed Asymmetric Domino Heck/Carbocyclization/Suzuki Reaction:A Dearomatization of Nonactivated Naphthalenes

Herein,we report a novel palladium(Pd)-catalyzed asymmetric domino Heck/carbocyclization/Suzuki reaction of N-(2-bromoaryl)-2-naphthylacrylamides.The reaction involves a novel and enantioselective dearomative 1,2-insertion of the naphthalene group,thus providing a unique dearomatization strategy of nonactivated naphthalenes.A new phosphoramidite ligand L12,which displayed excellent reactivity and enantioselectivity in the reaction,has been developed.

Spirocyclizative Remote Arylcarboxylation of Nonactivated Arenes with CO_(2) via Visible-Light-Induced Reductive Dearomatization

Visible-light-induced reductive dearomatization of nonactivated arenes is a very challenging transformation and remains in its infancy.Herein,we report a novel strategy to achieve a visible-light-induced spirocyclizative remote arylcarboxylation of nonactivated arenes including naphthalenyl-and phenyl-bearing aromatics with CO_(2) under mild conditions through a radical-polar crossover cascade(RPCC).This reductive dearomatization protocol rapidly delivers a broad range of spirocyclic and valuable carboxylic acid derivatives from readily accessible aromatic precursors with generally good regioselectivity and chemoselectivity.

Highly Diastereo-and Enantioselective Synthesis of Quinuclidine Derivatives by an Iridium-Catalyzed Intramolecular Allylic Dearomatization Reaction

Asymmetric construction of quinuclidine derivatives has been realized by an iridium-catalyzed allylic dearomatization reaction.The catalytic system,derived from[Ir(cod)Cl]2 and the Feringa ligand,tolerates a broad range of substrates.A large array of quinuclidine derivatives can be obtained under mild conditions in good to excellent yields(68%–96%),diastereoselectivity(up to>20/1 dr),and enantioselectivity(up to>99%ee).These pro-ducts feature versatile functional group diversity and can undergo diverse transformations.A model that accounts for the origin of the stereoselectivity has been proposed based on density functional theory(DFT)calculations.

Dearomatized Isoprenylated Acylphloroglucinol Derivatives with Potential Antitumor Activities from Hypericum henryi

A series of dearomatized isoprenylated acylphloroglucinols derivatives,hyperhenols A-E(1-5),as well as seven known analogues(6-12),were characterized from Hypericum henryi.Their structures were determined by combination of NMR,ECD spectroscopy,and X-ray difraction analysis.Compounds 1 and 6-8 were tested to exhibit potential antitumor properties,of which 6 and 7 inhibited cell growth through inducing apoptosis and cell cycle arrest.In addition,these compounds could induce autophagy and PINK1/Parkin-mediated mitophagy in cancer cell lines,as well as suppress lung cancer A549 cells metastasis in vitro.

Catalytic asymmetric dearomative azo-Diels–Alder reaction of 2-vinlyindoles

Due to the high electrophilic nature of azo-dienophiles, azo-Diels–Alder proceeds rapidly even without the need of a catalyst and is therefore regarded as the “click reaction”. This spontaneity causes strong background reaction and poses a daunting challenge to chemists for developing the catalytic asymmetric version. Reported herein is the first catalytic asymmetric dearomative azo-Diels–Alder reaction between2-vinylindoles and triazoledione. This protocol makes use of the high energy barrier of dearomatization to avert the strong background reaction of azo-Diels–Alder reaction, allowing the implementation of the projected reaction at ambient temperature. Density functional theory calculations have been performed to gain insights into the reaction mechanism and the origins of the enantioselectivity. By using this method,a variety of tetracyclic indole derivatives have been readily prepared in good to excellent yields and with excellent diastereo-and enantio–selectivities(33 examples, up to 97% yield and >99% ee, >20:1 dr).

Recent advances in catalytica symmetric Buchner reaction

Bichner reaction,as a unique type of expansive dearomatization,has become a practical strategy for the straightforward assembly of valuable functionalized cycloheptatrienes from ubiquitous aromatic precursors.Although the asymmetric version has been investigated since the early 1990s,enantioselective Bichner reaction is still limited by the catalyst type and substrate scope.This review aims to propose the limitation and possible development direction of this field by summarizing the evolution of catalytic asymmetric Bichner reaction,which is organized on the basis of intra-and intermolecular reactions.Considering the different metal carbene precursors,the reactions are further classified by carbene sources.