Carbazole-functionalized hyper-cross-linked polymers for CO₂ uptake based on Friedel–Crafts polymerization on 9-phenylcarbazole

• Dandan Fang,
• Xiaodong Li,
• Meishuai Zou,
• Xiaoyan Guo and
• Aijuan Zhang

Beilstein J. Org. Chem. 2019, 15, 2856–2863, doi:10.3762/bjoc.15.279

• a high surface area and a high total pore volume. The BET specific surface areas of P3 was up to 769 m2 g−1 with narrow pore size distribution and the CO2 adsorption capacity of P11 was up to 52.4 cm3 g−1 (273 K/1.00 bar). Keywords: 9-phenylcarbazole; CO2 uptake; Friedel–Crafts polymerization

• to monomer, the reaction temperature T1, the amount of used catalyst and the concentration of reactants. Additionally, the CO2 uptake of the obtained polymers was explored. Results and Discussion The synthesis of HCPs is shown in Scheme 1 and Table 1. Using the Friedel–Crafts reaction, 11 samples (P1

• carbon. Based on the above peaks in the solid state NMR, the Friedel–Crafts polymerization product was confirmed. TGA analysis The thermal stability of HCPs was investigated by TGA tests (Figure 3 and Supporting Information File 1, Figure S3). A slight weight loss at 100 °C was observed for P2, P4, P5

Acid-catalyzed rearrangements in arenes: interconversions in the quaterphenyl series

• Sarah L. Skraba-Joiner,
• Carter J. Holt and
• Richard P. Johnson

Beilstein J. Org. Chem. 2019, 15, 2655–2663, doi:10.3762/bjoc.15.258

• explain odd results from Friedel–Crafts reactions [19] and this type of process is sometime referred to as a Baddeley rearrangement. Many examples of alkyl group migration have been described [19]. Phenyl groups migrate easily and degenerate phenyl shifts in biphenyl were confirmed by isotopic labeling

Effect of ring size on photoisomerization properties of stiff stilbene macrocycles

• Sandra Olsson,
• Óscar Benito Pérez,
• Magnus Blom and
• Adolf Gogoll

Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233

• well-established reactions (Scheme 2). The indanone is formed by intramolecular Friedel–Crafts acylation of 2 under microwave radiation as reported by Oliverio et al. [23]. The second step is the demethylation of indanone methyl ether 3 by aluminium trichloride in toluene at reflux [24]. Two indanone

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• fluorination methods to these building blocks, such as Friedel–Crafts-type electrophilic halogenation [10][11], Sandmeyer-type reactions of diazonium salts [12], and halogenations of preformed organometallic reagents [13], commonly involve multiple steps, harsh reaction conditions, and the use of

Friedel–Crafts approach to the one-pot synthesis of methoxy-substituted thioxanthylium salts

• Kenta Tanaka,
• Yuta Tanaka,
• Mami Kishimoto,
• Yujiro Hoshino and
• Kiyoshi Honda

Beilstein J. Org. Chem. 2019, 15, 2105–2112, doi:10.3762/bjoc.15.208

• . Keywords: Friedel–Crafts reaction; metal-free conditions; one-pot synthesis; photoredox catalyst; thioxanthylium salt; Introduction Thioxanthylium salts are one of the important structural motifs found in biologically active compounds and photochemical materials [1][2][3][4][5][6][7][8]. Owing to these

• the synthesis of thioxanthylium salts and investigate their physical properties, we report the Friedel–Crafts approach as an efficient synthetic method of methoxy-substituted thioxanthylium salts (Scheme 1c). Results and Discussion Initially, we screened the reaction of bis(3,5-dimethoxyphenyl

• °’ = −0.79 V vs Fc/Fc+) afforded a negative shift compared to 4b (E°’ = −0.56 V vs Fc/Fc+). It is obviously indicated that the methoxy groups lower the reduction potential by their strong electron-donating effect. Conclusion We have developed the Friedel–Crafts approach as an efficient method to synthesize

A review of the total syntheses of triptolide

• Xiang Zhang,
• Zaozao Xiao and
• Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

• -phenylethylamine (49) to generate key tricyclic intermediates 51 and 52, a Pd(II)-catalyzed carbonylation–lactonization reaction of 9 to construct the butenolide (D-ring), and a Friedel–Crafts isopropylation to install the C-13 isopropyl group. Still, the construction of the C-5 trans junction A-/B-ring was

Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkyl-substituted benzimidazoles with arenes in the superacid CF₃SO₃H. NMR and DFT studies of dicationic electrophilic species

• Dmitry S. Ryabukhin,
• Alexey N. Turdakov,
• Natalia S. Soldatova,
• Mikhail O. Kompanets,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1962–1973, doi:10.3762/bjoc.15.191

• nab., 7/9, Saint Petersburg, 199034, Russian Federation 10.3762/bjoc.15.191 Abstract Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkylbenzimidazoles with arenes in the Brønsted superacid TfOH resulted in the formation of the corresponding Friedel–Crafts reaction products, 2-diarylmethyl and 2

• cations I', III', and VIII' in TfOH (Table 2). The peaks of the nitrogen atoms N1 and N3 appear in a rather narrow range of 148.7–158.9 ppm due to charge delocalization between these two nitrogen atoms for the corresponding resonance forms. Then, we carried out Friedel–Crafts reactions of benzimidazoles 1

• . Then, we studied reactions of 2-hydroxyalkylbenzimidazoles 3a–c, 4, 7, and 8. It was found that these reactions needed extremely harsh reaction conditions, heating in neat TfOH at 140 °C in glass high pressure tubes (Table 4, Scheme 2). Only at this high temperature the formation of Friedel–Crafts

Molecular basis for the plasticity of aromatic prenyltransferases in hapalindole biosynthesis

• Takayoshi Awakawa and
• Ikuro Abe

Beilstein J. Org. Chem. 2019, 15, 1545–1551, doi:10.3762/bjoc.15.157

• Aromatic prenyltransferases (PTases) are enzymes that catalyze Friedel–Crafts reactions between aromatic compounds and isoprenoid diphosphates. In hapalindole biosynthesis, the aromatic PTases AmbP1 and AmbP3 exhibit surprisingly plastic selectivities. AmbP1 not only transfers the geranyl group on the C-3

• AmbP1 and AmbP3 functions, elucidated through their X-ray crystal structures. The knowledge presented here will contribute to the understanding of aromatic PTase reactions and will enhance their uses as biocatalysts. Keywords: crystal structure; cyanobacteria; Friedel–Crafts reaction; hapalindole

• ; prenyltransferase; Introduction Aromatic prenyltransferases (PTases) catalyze Friedel–Crafts reactions between aromatic prenyl acceptors and isoprenoid diphosphate prenyl donors to construct C–C, C–O, or C–N bonds, which enrich the structural diversity of aromatic natural products [1][2]. Their reactions are

Superelectrophilic carbocations: preparation and reactions of a substrate with six ionizable groups

• Sean H. Kennedy,
• Makafui Gasonoo and
• Douglas A. Klumpp

Beilstein J. Org. Chem. 2019, 15, 1515–1520, doi:10.3762/bjoc.15.153

• proposed involving tetra-, penta-, or hexacationic species. Keywords: cation; Friedel–Crafts; heterocycle; superacid; superelectrophile; Introduction During the 1970s and 80s, Olah and co-workers described the novel chemistry of highly-charged organic cationic species. This work lead to the concept of

Mechanochemical Friedel–Crafts acylations

• Mateja Đud,
• Anamarija Briš,
• Iva Jušinski,
• Davor Gracin and
• Davor Margetić

Beilstein J. Org. Chem. 2019, 15, 1313–1320, doi:10.3762/bjoc.15.130

• Mateja Dud Anamarija Bris Iva Jusinski Davor Gracin Davor Margetic Ruđer Bošković Institute, Bijenička cesta 54, HR-10002 Zagreb, Croatia 10.3762/bjoc.15.130 Abstract Friedel–Crafts (FC) acylation reactions were exploited in the preparation of ketone-functionalized aromatics. Environmentally more

• studied by in situ Raman and ex situ IR spectroscopy. Keywords: ball milling; Friedel–Crafts reaction; mechanochemistry; Introduction The Friedel–Crafts reaction (FCR) is a very powerful tool in organic chemistry for the synthesis of aromatic ketones. It is of great industrial importance and widely used

• of in situ IR spectroscopy in solution [63]. Conclusion In conclusion, the experimental results demonstrate that Friedel–Crafts acylations could be effectively carried out under solid state ball-milling conditions. The reaction takes place by the initial complexation of the carbonyl group of the

Robust perfluorophenylboronic acid-catalyzed stereoselective synthesis of 2,3-unsaturated O-, C-, N- and S-linked glycosides

• Madhu Babu Tatina,
• Xia Mengxin,
• Rao Peilin and
• Zaher M. A. Judeh

Beilstein J. Org. Chem. 2019, 15, 1275–1280, doi:10.3762/bjoc.15.125

• activation of alcohols [24], epoxide opening [25][26], Friedel–Crafts alkylations [27], dehydrative glycosylation [28] and many other reactions [29][30][31]. The robustness and mildness of organoboronic acid catalysts in comparison to traditional strong Lewis and Brønsted acid catalysts inspired us to

Mechanochemical synthesis of hyper-crosslinked polymers: influences on their pore structure and adsorption behaviour for organic vapors

• Sven Grätz,
• Sebastian Zink,
• Hanna Kraffczyk,
• Marcus Rose and
• Lars Borchardt

Beilstein J. Org. Chem. 2019, 15, 1154–1161, doi:10.3762/bjoc.15.112

• Universität Darmstadt, Darmstadt, Germany 10.3762/bjoc.15.112 Abstract This study elucidates a mechanochemical polymerization reaction towards a hyper-crosslinked polymer as an alternative to conventional solvent-based procedures. The swift and solvent-free Friedel–Crafts alkylation reaction yields a porous

• , they are formed by a non-directed aromatic substitution (Friedel–Crafts alkylation) either by intramolecular functional groups or using external crosslinkers. These reactions yield very high crosslinking degrees in amorphous framework structures and hence, enable highest specific BET (Brunauer–Emmett

• POPs (porous organic polymers) [4] are currently in the focus of research. The modular bottom-up building concept of these organic materials allows for tailoring of materials properties towards desired applications. POPs synthesis can be achieved by a huge variety of reactions ranging from Friedel

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• with the nucleophilic aromatic ring in a Friedel–Crafts alkylation process, thus incorporating the carbon atom in a formal C(sp2)–H/C(sp3)–H cross-dehydrogenative coupling. Finally, an oxidation of sulfide 7 to sulfoxide 8 and the subsequent attack of amide 2 with cleavage of the C–S bond and formation

• , that rearranges to afford cationic isoindolinone moiety 95. Then, benzene derivative 86 would react by a Friedel–Crafts type reaction to form diaryl γ-lactam 88. When ketone 89 is used instead of arene 86, the enol form would act as nucleophile and upon reaction with carbocation 95, compounds 90 could

• be isolated. Finally, cyclopropyl ketone 91 would first rearrange by copper catalysis and the so-obtained furane derivative 96 would add to the carbocation in 95, followed by Friedel–Crafts cyclization, thus generating the polycyclic isoindolinones 92 in a formal hetero [4 + 2] cycloaddition process

Heck- and Suzuki-coupling approaches to novel hydroquinone inhibitors of calcium ATPase

• Robert J. Kempton,
• Taylor A. Kidd-Kautz,
• Soizic Laurenceau and
• Stefan Paula

Beilstein J. Org. Chem. 2019, 15, 971–975, doi:10.3762/bjoc.15.94

• silfen [11]. Alkylation of 4 under typical Friedel–Crafts conditions gave 5. In the case of 5a, the 1H NMR of the crude product, while clearly showing that it was the desired 4-substituted isomer (1H singlets at δ 6.89 and 7.02), also exhibited an impurity (doublets at δ 6.83 and 7.12, J = 3.0 Hz

• cytosolic calcium levels and on the viability of both cancer and healthy cells. Thapsigargin- and hydroquinone-based SERCA inhibitors. Friedel–Crafts alkylation of 4. Heck cross-coupling reactions. Suzuki approach to a tethered hydroquinone. Supporting Information Supporting Information File 369

Synthesis and SAR of the antistaphylococcal natural product nematophin from Xenorhabdus nematophila

• Frank Wesche,
• Hélène Adihou,
• Thomas A. Wichelhaus and
• Helge B. Bode

Beilstein J. Org. Chem. 2019, 15, 535–541, doi:10.3762/bjoc.15.47

• initiated. The syntheses of the appropriate azatryptamine derivatives (17, 18, 25, and 26) were achieved from the non-expensive and commercially available 4- and 7-azaindole (13 and 20), respectively. First, 13 and 20 were converted in a Friedel–Crafts acylation with chloroacetyl chloride (ClCH2COCl) and

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• -acyl- or 1,2,3,5-tetra-O-acyl-D-ribofuranose is used, as fully acylated ribofuranoses require the usage of Friedel–Crafts catalysts to be activated as glycosylation reagents. As it is shown in Figure 2, reactions between compounds A and B may result in two anomeric α- and β-forms of nicotinamide

• on the glycosylation of silylated heterocyclic bases with acylated (halo)ribofuranoses and Friedel–Crafts catalysts. The main advantage of this method is that the silylation converts polar, often poorly soluble, heterocyclic bases into lipophilic silyl derivatives, resulting in homogeneous reaction

• mixtures [24]. In the Vorbrüggen version of the silyl Hilbert–Johnson method, trimethylsilyl trifluoromethanesulfonate (TMSOTf) is used as a Friedel–Crafts catalyst. The TMSOTf-mediated glycosylation of Nam (1a) with tetra-O-acetyl-β-D-ribofuranose was first proposed by Tanimori et al. in 2002 [29] (Scheme

Gold-catalyzed ethylene cyclopropanation

• Silvia G. Rull,
• Andrea Olmos and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2019, 15, 67–71, doi:10.3762/bjoc.15.7

• additives [11], alkylating reagent in the Friedel–Crafts synthesis of indanones [12] or as synthon toward the introduction of cyclopropyl moieties in compounds with medicinal or biological interest [13][14]. In view of the lack of examples of direct conversions of ethylene into cyclopropanecarboxylates, and

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• 1 h [67]. The hypercrosslinked supermicroporous polymer (HMP-1, 113) was also designed and prepared by iron(III) chloride catalyzed Friedel–Crafts alkylation of carbazole (111) with α,α′-dibromo-p-xylene (112). In the next step, HMP-1 (113) was sulfonated by Cl-SO3H to form HMP-1-SO3H material 114

• copolymer synthesized by Friedel–Crafts alkylation of triphenylamine (115) with dibromo-p-xylene 112 was prepared (Scheme 21). After the sulfonation process, the resulted material has been employed as a heterogeneous, reusable, and environmentally benign catalyst in the multicomponent synthesis of

Gold-catalyzed post-Ugi alkyne hydroarylation for the synthesis of 2-quinolones

• Xiaochen Du,
• Jianjun Huang,
• Anton A. Nechaev,
• Ruwei Yao,
• Jing Gong,
• Erik V. Van der Eycken,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2018, 14, 2572–2579, doi:10.3762/bjoc.14.234

• derivatives with most recent strategies focusing on the implementation of transition metal-catalyzed C–H activation methods [35][36]. One of the common approaches towards 2-quinolones 2 involves the intramolecular Friedel–Crafts hydroarylation [37][38] of N-arylamides of 3-substituted propynoic acids 1

• outcome under similar settings (Scheme 1a). Consequently, several catalytic methods were developed to extend the scope of this Friedel–Crafts process to substrates such as 1c and 1d featuring highly electron-rich N-aryl moieties (Scheme 1b) [42][43][44]. Finally, following the success of the above

• . Another important highlight of the developed process is that it strongly benefits from the employment of fluorinated alcohols as environmentally benign solvents. Scope of the protocol. Synthesis of 2-quinolones 2 through intramolecular Friedel–Crafts hydroarylation of N-aryl propargylamides 1. Strategy

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• -mediated glycosylation led us to apply the reaction to the synthesis of carbocyclic nucleosides. In addition, we were also encouraged by the study of Ochiai, who developed the Friedel–Crafts reaction via umpolung of allylsilanes using hypervalent-iodine reagents [61] and the pioneering work on C–N bond

• developed. Since the Friedel–Crafts type reaction involved carbocation intermediate, the reaction always gave a mixture of products. Unfortunately, the reaction was not efficient. However, it is worthy that the oxidative coupling reaction contains a novel type of C–N bond formation and would help to

Synthesis of chiral 3-substituted 3-amino-2-oxindoles through enantioselective catalytic nucleophilic additions to isatin imines

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 1349–1369, doi:10.3762/bjoc.14.114

• additions to isatin imines have been developed, including Mannich reactions, aza-Morita–Baylis–Hillman reactions, Friedel–Crafts reactions, aza-Henry reactions, additions of heteronucleophiles, Strecker reactions, among others. The goal of this review is to update the catalytic asymmetric synthesis of

• –Hillman reactions, Friedel–Crafts reactions, aza-Henry reactions, domino reactions initiated by nucleophilic additions to isatin imines, and miscellaneous reactions. Most of the reactions depicted in this review have been promoted by a wide variety of chiral organocatalysts but chiral metal catalysts have

• ) were obtained in the reaction of the N-benzyl 5-Br substituted substrate (R1 = 5-Br, R2 = Bn). Enantioselective Friedel–Crafts reactions The Friedel–Crafts reaction is widely employed in total synthesis [63][64][65]. In 2015, Pedro et al. reported the first asymmetric Friedel–Crafts reaction of N-Boc

A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

• Anna Czarnecka,
• Emilia Kowalska,
• Agnieszka Bodzioch,
• Joanna Skalik,
• Marek Koprowski,
• Krzysztof Owsianik and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105

• was observed instead [23]. Diarylmethanes were also obtained in the Friedel–Crafts reactions of arenes with primary benzyl alcohols, aryl acetals, and benzyl esters [1]. Benzyl fluorides (in 1,1,1,3,3,3-hexafluoroisopropanol in the presence of a catalytic amount of trifluoroacetic acid [24]) as well

• as benzotrifluorides (employed in hydrodefluorinative Friedel–Crafts alkylations catalyzed by alumenium ions [25]) were interesting, alternative substrates for alcohols, acetals and esters. A large group of synthetic procedures for the synthesis of diarylmethanes are deoxygenations of secondary

Rapid transformation of sulfinate salts into sulfonates promoted by a hypervalent iodine(III) reagent

• Elsa Deruer,
• Vincent Hamel,
• Samuel Blais and
• Sylvain Canesi

Beilstein J. Org. Chem. 2018, 14, 1203–1207, doi:10.3762/bjoc.14.101

• such as thiophene or anisole. It should be stressed that the formation of substituted aromatic systems through a Friedel–Crafts type process [36] is an argument in favor of the formation of the electrophilic sulfonium species 3 (Scheme 1). In the presence of thiophene, compounds 9 were obtained in 23

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• chloride (SOCl2) which underwent intramolecular Friedel–Crafts reaction in presence of Lewis acid to give 3-methyl-1-phenyl-1H-indeno[2,1-e]pyrazolo[3,4-b]pyrazin-5-one (233). Compound 233 was used to synthesize several other indenopyrazolopyrazinone derivatives by reaction with active methylene compounds