Friedel-Crafts Alkenylation Research Articles

Spherical hollow mesoporous silica supported phosphotungstic acid as a promising catalyst for α-arylstyrenes synthesis via Friedel-Crafts alkenylation

In this work, a spherical hollow mesoporous silica (SHMS) with high surface area (902 m2/g) and large mesopore volume (1.31 cm3/g) was prepared via a facile and scalable two-step soft-hard dual template-assisted sol-gel approach (OSDSG) by using glucose-derived carbon nano/micro particles (NMCP) as a hard template and cetyltrimethylammonium bromide (CTAB) as a soft template, respectively, in which the size-preselected carbon submicro-particle was used to replace ploymer sphere, and no extra precious additives like n-octadecyltrimethoxysilane (C18TMS). Supported phosphotungstic acid (PTA) catalysts on SHMS (PTA/SHMS) and on previously reported spherical mesoporous silica (PTA/SMS) with 25 wt% of PTA loading were prepared and employed as solid acid catalysts for diverse reactions. Transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray diffraction (XRD), and NH3 temperature-programmed desorption (NH3-TPD) techniques were employed to characterize the nature of carriers and supported PTA catalysts for revealing the structure-performance relationship. The developed PTA/SHMS catalyst demonstrates much higher catalytic activity than PTA/SMS for diverse reactions including alkenylation, esterification, alkylation, and benzylation, ascribed to the strengthened mass transfer and enlarged exposure degree of acidic sites to reactants those resulting from unique hollow and mesoporous morphology. Moreover, PTA/SHMS catalyst also exhibits outstanding catalytic performance for the diverse α-arylstyrenes via solid acid-mediated alkenylation. PTA/SHMS could be considered as a practical solid acid catalyst for diverse transformations.

Diversity‐Oriented Synthetic Endeavors of Newly Designed Ferrier and Ferrier‐Nicholas Systems Derived from 1‐C‐Alkynyl‐2‐deoxy‐2‐C‐Methylene Pyranosides

Novel pyranose derivatives that display Ferrier‐ and Ferrier‐Nicholas‐like reactivity have been designed. These systems: 1‐C‐alkynyl‐2‐deoxy‐2‐C‐methylene pyranosides (Ferrier), and their corresponding dicobalthexacarbonyl alkenyl derivatives (Ferrier‐Nicholas), which can be accessed by a concise synthetic route from commercially available tri‐O‐acetyl‐d‐glucal, allow the incorporation of two nucleophiles (at positions C‐3 and C‐2′) in the pyranose ring. The study of these systems has resulted in the discovery of novel reaction patterns that allow, among others, access to open‐chain derivatives, branched pyranosides, 1,6‐anhydro derivatives and, when reacting with indole, access to a new family of tetracyclic indole‐containing carbohydrate derivatives, namely, cyclohepta[b]indole‐fused glycals. The latter are, most likely, formed by a bis Ferrier‐type rearrangement followed by an unusual intramolecular 7‐endo‐dig Friedel–Crafts alkenylation of one of the indole moieties by the C‐1 alkyne.

Synthesis of spiroindenyl-2-oxindoles by montmorillonite K-10-catalyzed tandem Friedel-Crafts alkenylation/hydroarylation of propargylic alcohols with sterically hindered and electron-rich arenes

Various spiroindenyl-2-oxindoles have been synthesized in a one-pot reaction from isatin-derived propargylic alcohols with sterically hindered and electron-rich arenes such as 2-phenylindole and 1,3,5-trimethoxybenzene. The reaction involved montmorillonite K-10-catalyzed tandem Friedel-Crafts alkenylation and a following hydroarylation of an allene intermediate.

Supported phosphotungstic acid catalyst on mesoporous carbon with bimodal pores: A superior catalyst for Friedel-Crafts alkenylation of aromatics with phenylacetylene

Supported phosphotungstic acid (PTA) catalysts on diverse carriers containing the modified commercially available activated carbon (AC), classical mesoporous carbon via SBA-15 hard template method (CMK-3), and the mesoporous carbon with high surface area and bimodal pores through evaporation-induced tri-constituent co-assembly approach (MC) by using a facile wet impregnation method were employed as solid acid catalysts for Friedel-Crafts alkenylation of p-xylene with phenylacetylene. N2 adsorption–desorption, X-ray diffraction (XRD), and NH3 temperature-programmed desorption (NH3-TPD) characterization techniques were employed to reveal the structure-performance relationship. PTA/MC exhibits much superior catalytic performance to the previously reported PTA/AC, and even to PTA/CMK-3. The PTA/MC catalysts were optimized by varying the PTA loading, and the optimum PTA loading is 35%. The close to 100% of conversion towards phenylacetylene can be achieved in the presence of 2.67% of the 35% PTA/MC solid acid catalyst. It is also found that catalytic properties of the solid acids are strongly depended on acidic properties that affected by the textural properties of supports and PTA loading, as well as the accessibility of active sites affected by specific surface area and pore structure of catalyst. Moreover, the 35wt.% PTA/MC catalyst has demonstrated outstanding catalytic performance for the Friedel-Crafts alkenylation of diverse aromatics to their corresponding α-arylstyrenes.

Tuning of the textural features and acidic properties of sulfated mesoporous lanthana-zirconia solid acid catalysts for alkenylation of diverse aromatics to their corresponding α-arylstyrenes

The textural features and acidic properties of sulfated mesoporous lanthana-zirconia solid acids (SO42−/meso-La0.1Zr0.9Oδ) were efficiently tuned by modifying the conditions used to prepare the meso-La0.1Zr0.9Oδ composites, such as the molar ratio of the template to La and Zr metal ions (Nt/m), molar ratio of ammonia to La and Zr metal ions (Na/m), hydrothermal temperature (Thydro), and hydrothermal time (thydro). The effect of the textural features and acidic properties on the catalytic performance of solid acid catalysts for alkenylation of p-xylene with phenylacetylene was investigated. Various characterization techniques such as N2 physisorption, X-ray diffraction, NH3 temperature-programmed desorption, and thermogravimetric analysis were employed to reveal the relationship between the nature of catalyst and its catalytic performance. It was found that the catalytic performance significantly depended on the textural features and acidic properties, which were strongly affected by preparation conditions of the meso-La0.1Zr0.9Oδ composite. Appropriate acidic sites and high accessibility were required to obtain satisfactory catalytic reactions for this reaction. It was also found that the average crystallite size of t-ZrO2 affected by the preparation conditions had significant influence on the ultrastrong acidic sites of the catalysts. The optimized SO42−/meso-La0.1Zr0.9Oδ catalyst exhibited much superior catalytic activity and coke-resistant stability. Moreover, the developed SO42−/meso-La0.1Zr0.9Oδ catalyst demonstrated excellent catalytic performance for alkenylation of diverse aromatics with phenylacetylene to their corresponding α-arylstyrenes. Combining the previously established complete regeneration of used catalysts by a facile calcination process with the improved catalytic properties, the developed SO42−/meso-La0.1Zr0.9Oδ solid acid could be a potential catalyst for industrial production of α-arylstyrenes through clean and atom efficient solid-acid-mediated Friedel-Crafts alkenylation of diverse aromatics with phenylacetylene.

Supported phosphotungstic acid catalyst on modified activated carbon for Friedel–Crafts alkenylation of diverse aromatics to their corresponding α-arylstyrenes

The supported phosphotungstic acid catalysts on modified activated carbon (PTA/AC) prepared by a facile wet impregnation method were employed for Friedel–Crafts alkenylation of diverse aromatics with phenylacetylene to synthesize their corresponding α-arylstyrenes. Reaction results demonstrate that the fabricated PTA/AC catalyst with 30wt.% PTA loading exhibits outstanding catalytic performance. The 100% conversion of phenylacetylene with 95.7% selectivity towards α-(2,5-dimethylphenyl) styrene can be achieved over the developed 30wt.% PTA/AC catalyst under optimized reaction conditions, and no visible loss in catalytic performance can be observed after it suffers from several times recycling. The various characterization techniques including X-ray diffraction, N2 adsorption–desorption, Fourier transform infrared spectroscopy, and NH3 temperature-programmed desorption were employed to reveal the relationship between the catalysts nature and catalytic properties. Moreover, the results on the scope of aromatics for the Friedel–Crafts alkenylation illustrate that the developed PTA/AC alkenylation catalyst can be efficiently catalyze the diverse aromatics and even for the electron deficient chlorobenzene. The developed PTA/AC catalyst, using the modified low-cost and sustainable AC as support, may be a robust and promising candidate for highly-efficient and clean α-arylstyrenes production through Friedel–Crafts alkenylation of diverse aromatics including electron-donating and electron-withdrawing groups substituted benzene derivatives as well as heterocyclic and polypolycyclic arenes with phenylacetylene.

Brønsted acid mediated alkenylation and copper-catalyzed aerobic oxidative ring expansion/intramolecular electrophilic substitution of indoles with propargyl alcohols: a novel one-pot approach to cyclopenta[c]quinolines.

Copper-catalyzed oxidative ring-expansion/intramolecular electrophilic substitution of 3-dienylindoles leading to cyclopenta[c]quinolines and 3-indenylindoles under aerobic conditions is described. The precursors, 3-dienylindoles, are formed via Friedel-Crafts alkenylation followed by isomerization reactions of 2-substituted indoles with tertiary propargyl alcohols under Brønsted acid mediation. The methyl (sp(3)-C) group present in the propargyl alcohol becomes a part of a six-membered ring in the final ring-expansion products, the cyclopenta[c]quinolines which are fluorescence active. Based on these observations, a novel one-pot strategy for ring expansion from indole to cyclopenta[c]quinoline is discovered.

Sc(OTf)3-Catalyzed Synthesis of Indoles and SnCl4-Mediated Regioselective Hydrochlorination of 5-(Arylamino)pent-3-yn-2-ones

Highly substituted indole derivatives bearing alkyl and aryl moieties can be prepared by Sc(OTf)(3)-catalyzed Friedel-Crafts alkenylation of 5-(arylamino)pent-3-yn-2-ones. In addition, a method for regioselective hydrochlorination of 5-(arylamino)pent-3-yn-2-ones mediated by SnCl(4) in moderate to good yields (up to 84%) has been developed. The resulting exclusive Z-selectivity of the C-Cl bond can be further exploited using cross C-N coupling reactions.

TfOH-promoted transformation from 2-alkynylphenyl isothiocyanates to quinoline-2-thiones or indoles

A variety of 4-arylquinoline-2-thiones and 3-arylthieno[2,3- b]indoles were synthesized in high yields via TfOH-promoted tandem Friedel–Crafts alkenylation–cyclization reactions of 2-alkynylphenyl isothiocyanates.

ChemInform Abstract: Synthesis of Quinoline‐2‐thiones via Tandem Indium(III)‐Promoted Friedel—Crafts Alkenylation—Cyclization of 2‐Alkynylphenyl Isothiocyanates.

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ChemInform Abstract: Thermodynamically and Kinetically Controlled Friedel—Crafts Alkenylation of Arenes with Alkynes Using an Acidic Fluoroantimonate(V) Ionic Liquid as Catalyst.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Metal Triflate Catalyzed Regio‐ and Stereoselective Friedel—Crafts Alkenylation of Arenes with Alkynes in an Ionic Liquid: Scope and Mechanism.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Metal Triflate‐Catalyzed Regio‐ and Stereoselective Friedel–Crafts Alkenylation of Arenes with Alkynes in an Ionic Liquid: Scope and Mechanism

AbstractIn the metal triflate‐catalyzed hydroarylation of alkynes, employing an ionic liquid dramatically enhanced the catalytic activities, resulting in broadening the scope of substrates (arenes and alkynes). In some cases, even reactions that were not possible in conventional organic solvents proceeded smoothly in ionic liquids. Moreover, the ionic liquid phase containing catalyst could be readily recovered by simple decantation of the organic layer after reaction and reused for the following runs without any significant loss of activity. Mechanistic studies including 13C NMR analysis of reaction intermediates and isotope experiments confirmed for the first time that this type of reaction proceeds via vinyl cationic intermediates.

Thermodynamically- and kinetically-controlled Friedel–Crafts alkenylation of arenes with alkynes using an acidic fluoroantimonate(v) ionic liquid as catalyst

By employing superacidic fluoroantimonate ionic liquid (IL), [bmim][Sb(2)F(11)], as catalyst, not only thermodynamically-controlled but also kinetically-controlled Friedel-Crafts alkenylations of arenes with alkynes have been realized for the first time.

Synthesis of Ene‐ynamide Derivatives Starting from Baylis—Hillman Adducts: Isomerization with the Aid of π‐Cation Interaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Ene-ynamide Derivatives Starting from Baylis-Hillman Adducts: Isomerization with the Aid of π-Cation Interaction

Recently, we have developed a facile synthetic method of 9-phenyl-7H-benzocycloheptene derivatives from the alkynyl moiety-containing Baylis-Hillman adducts, which involved intramolecular Friedel-Crafts alkenylation reaction of triple bond-tethered methyl cinnamates. We also reported the synthesis of iodoenol lactones from the same substrates via the typical iodolactonization protocol. During the investigation we envisaged that we could prepare the corresponding lactam derivatives from the acetates of the Baylis-Hillman adducts by using similar strategy as shown in Scheme 1. However, during the investigation for the synthesis of lactam derivatives from 3, we found the formation of isomerized conjugated ene-ynamide derivatives 4 unexpectedly and wish to report herein the results (Scheme 1). Conjugated or non-conjugated ene-ynamides are frequently used as synthetic intermediates, and as a key backbone of β-turn mimetics, tweezers-type host molecules, and a basic unit of molecular nanostructures. The triple bond-containing amide derivatives 3 were prepared from the corresponding ester 2. Hydrolysis of 2 in aq THF with LiOH and the following condensation with appropriate amines by using 1,1'-carbonyldiimidazole afforded 3 in moderate yields (61-82%) and the results are summarized in Table 1. Initially, we tried many reaction conditions including I2/NaHCO3, I2/K2CO3, I2/LiHMDS (lithium bis(trimethylsilyl)amide) in order to synthesize the original target compounds, lactam derivatives. But, all the efforts resulted in failure for the synthesis of lactam derivatives. Thus, as a next choice, we examined the possibility for the lactamization in the presence of a strong base such as NaH, n-BuLi, or LiHMDS without the aid of electrophile like iodine. However, we observed the unusual formation of conjugated ene-ynamide 4a in low yield from 3a instead of the desired lactam derivative when we used LiHMDS, unexpectedly. Intrigued by the results we examined the isomerization conditions deeply and finally we could increase the yield of 4a up-to 60%, under the influence of LiHMDS (1.1 equiv, THF). The structure of 4a was conformed by IR, H, C, and mass spectroscopy. The synthesis of ene-ynamide is very important as mentioned above, thus we examined the isomerization reactions of 3b-e and the results are summarized in Scheme 1 and in Table 1. As shown, the isomerization for 3a-c occurred effectively with the aid of LiHMDS (1.1 equiv.) in THF at room temperature. Use of less amounts of LiHMDS resulted in dramatic decrease in yields. The isomerization of 3d and 3e did not occur, however, under the same conditions (condition A). After devoting much efforts we finally found that the combination

Dramatic Enhancement of Catalytic Activity in an Ionic Liquid: Highly Practical Friedel–Crafts Alkenylation of Arenes with Alkynes Catalyzed by Metal Triflates

Eine einfache und hoch effiziente Variante der Friedel-Crafts-Alkenylierung von Arenen beruht auf dem Einsatz eines Metalltriflat-Katalysators in einer ionischen Flüssigkeit (siehe Schema, bmim=1-Butyl-3-methylimidazolium, Tf=Trifluormethansulfonyl). So wird die katalytische Aktivität deutlich erhöht und die Bildung von Nebenprodukten zurückgedrängt. Mit diesem System gelangen einige Reaktionen, die in gängigen organischen Lösungsmitteln nicht möglich sind.

Dramatic Enhancement of Catalytic Activity in an Ionic Liquid: Highly Practical Friedel–Crafts Alkenylation of Arenes with Alkynes Catalyzed by Metal Triflates

Dramatic Enhancement of Catalytic Activity in an Ionic Liquid: Highly Practical Friedel–Crafts Alkenylation of Arenes with Alkynes Catalyzed by Metal Triflates

Synthesis of Methyl 9‐Phenyl‐7H‐benzocycloheptene‐6‐carboxylates from Baylis—Hillman Adducts: Use of Intramolecular Friedel—Crafts Alkenylation Reaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of methyl 9-phenyl-7 H-benzocycloheptene-6-carboxylates from Baylis–Hillman adducts: use of intramolecular Friedel–Crafts alkenylation reaction

We developed a facile synthetic method for 9-phenyl-7 H-benzocycloheptene derivatives from the Baylis–Hillman adducts. Our method involved intramolecular Friedel–Crafts alkenylation reaction of triple bond-tethered methyl cinnamates.