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

Stereochemical outcomes of C–F activation reactions of benzyl fluoride

• Neil S. Keddie,
• Pier Alexandre Champagne,
• Justine Desroches,
• Jean-François Paquin and
• David O'Hagan

Beilstein J. Org. Chem. 2018, 14, 106–113, doi:10.3762/bjoc.14.6

• C–F activation of benzylic fluorides for nucleophilic substitutions and Friedel–Crafts reactions, using a range of hydrogen bond donors such as water, triols or hexafluoroisopropanol (HFIP) as the activators. This study examines the stereointegrity of the C–F activation reaction through the use of

• ]. Protocols using water/isopropanol [3], optimally coordinated triols [4][5], and hexafluoroisopropanol (HFIP) [6][7] as the corresponding hydrogen bond donors have shown considerable success. This mode of activation has been demonstrated for amination [3][4][5] and Friedel–Crafts reactions [6][7] on benzylic

• substantial F···HOR hydrogen bond interactions, rather than through electrostatic stabilisation only [3]. This stabilisation was suggested to lead to a purely associative bimolecular (SN2) mechanism. The authors also studied the C–F activated Friedel–Crafts reactions [6][7] using very strong hydrogen bond

Ring-size-selective construction of fluorine-containing carbocycles via intramolecular iodoarylation of 1,1-difluoro-1-alkenes

• Takeshi Fujita,
• Ryo Kinoshita,
• Tsuyoshi Takanohashi,
• Naoto Suzuki and
• Junji Ichikawa

Beilstein J. Org. Chem. 2017, 13, 2682–2689, doi:10.3762/bjoc.13.266

• latter case, the domino-Friedel–Crafts-type cyclization proceeded via the cleavage of two carbon–fluorine bonds to afford polycyclic aromatic hydrocarbons [15][16][17][18][19][20][21]. Both types of cationic cyclization proceeded exclusively at the carbon atoms α to the fluorine substituents, because the

• intermediates [23][24][25][26][27]. Thus, we examined and eventually achieved complete control over the regioselectivity at the carbon atoms in β-position as well as those in α-position to the fluorine in the intramolecular Friedel–Crafts-type iodoarylation of 1,1-difluoro-1-alkenes bearing a biaryl group

Synthesis of 1,3-cis-disubstituted sterically encumbered imidazolidinone organocatalysts

• Jan Wallbaum and
• Daniel B. Werz

Beilstein J. Org. Chem. 2017, 13, 2577–2583, doi:10.3762/bjoc.13.254

• accessible from amino acids, are widely used in these kinds of reactions [13][14][15][16][17][18]. More recent examples demonstrate the applicability in various reactions like diastereoselective α-fluorination [19], total syntheses [20][21], cross-dehydrogenative couplings [22], selectivity-reversed Friedel

• –Crafts alkylation [23] and in combination with photoredox catalysis (Scheme 1a) [24]. The enantioselective α-alkylation was achieved by merging the common photoredox catalyst Ru(bpy)3Cl2 with imidazolidinone catalyst 3a·TfOH, controlling the stereochemistry of the radical addition via an intermediate

Pyrene–nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies

• Artur Jabłoński,
• Yannic Fritz,
• Hans-Achim Wagenknecht,
• Rafał Czerwieniec,
• Tytus Bernaś,
• Damian Trzybiński,
• Krzysztof Woźniak and
• Konrad Kowalski

Beilstein J. Org. Chem. 2017, 13, 2521–2534, doi:10.3762/bjoc.13.249

• various aryl starting materials [24][25][26]. In this work, the starting material 1-(3-chloropropionyl)pyrene (1), was obtained via Friedel–Crafts reaction of pyrene with 3-chloropropionyl chloride [27]. Subsequently, the pyrenyl–nucleobase conjugates 2 and 3 were obtained by reactions of 1-(3

A novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines

• Benedikt C. Melzer and
• Franz Bracher

Beilstein J. Org. Chem. 2017, 13, 1564–1571, doi:10.3762/bjoc.13.156

• ) [17], which start with the synthesis of 1-(2-bromoaryl)isoquinolines using Bischler–Napieralski chemistry, followed by tedious replacement of the bromine substituent by cyanide (for modern variants, see ref. [18][19]), and subsequent conversion to a carboxylate and Friedel–Crafts-type cyclization

• starting from an isoquinoline bearing an ester group at C-8. In a photoredox-catalyzed direct C–H arylation a 4-methoxyphenyl residue from a methoxyphenyldiazonium salt was introduced at C-1, and after ester hydrolysis intramolecular Friedel–Crafts acylation afforded menisporphine (2). In continuation of

• type of intramolecular Friedel–Crafts-type acylations, and trifluoromethanesulfonic acid [25] is superior to polyphosphoric acid [26][27] for the synthesis of polycyclic ketones. Unfortunately, direct cyclization of esters 10a–c using this reagent failed completely, despite numerous variations of the

Sugar-based micro/mesoporous hypercross-linked polymers with in situ embedded silver nanoparticles for catalytic reduction

• Qing Yin,
• Qi Chen,
• Li-Can Lu and
• Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 1212–1221, doi:10.3762/bjoc.13.120

• .13.120 Abstract Porous hypercross-linked polymers based on perbenzylated monosugars (SugPOP-1–3) have been synthesized by Friedel–Crafts reaction using formaldehyde dimethyl acetal as an external cross-linker. Three perbenzylated monosugars with similar chemical structure were used as monomers in order

• -linkers [4], and self-polycondensation of small molecular monomers [5]. Since the Tan group proposed the new synthetic strategy that "knits" low functionality rigid aromatic compounds with formaldehyde dimethyl acetal (FDA) as an external cross-linking agent through a Friedel–Crafts reaction to synthesize

• synthesized using a Friedel–Crafts hypercross-linking reaction via knitted perbenzylated monosugars by FDA. Three perbenzylated monosugars Sug-1–3 having similar chemical structure were used as monomers to tune the porosity and PSD. The SSA values of the obtained porous polymer are around 1000 m2 g−1. As the

Regioselective (thio)carbamoylation of 2,7-di-tert-butylpyrene at the 1-position with iso(thio)cyanates

• Anna Wrona-Piotrowicz,
• Marzena Witalewska,
• Janusz Zakrzewski and
• Anna Makal

Beilstein J. Org. Chem. 2017, 13, 1032–1038, doi:10.3762/bjoc.13.102

• , although substitution at the 1-position prevails. For ethoxycarbonyl isothiocyanate, apart from the 1-substituted thioamide, 1,8-disubstituted thioamide and 2,7-di-tert-butylpyrene-1-carbonitrile are formed (especially at longer reaction times). Keywords: amide; Friedel–Crafts; isocyanate; isothiocyanate

• , 6 and 8 of 1. However, Friedel–Crafts alkylation of 1 with an excess of sterically hindered tert-butyl chloride leads to 2,7-di-tert-butylpyrene (2) [8]. This compound, owing to the presence of two bulky and electron-donating tert-butyl groups, displays different reactivity towards electrophiles. It

• has been reported that nitration and bromination of 2 take place at the 1-position (however, the bromine atom in 1-bromopyrene can migrate into the 4-position in the presence of AlCl3) [8][9], whereas Friedel–Crafts acylation and Vilsmeier formylation take place at the 4-position [10]. We recently

Automating multistep flow synthesis: approach and challenges in integrating chemistry, machines and logic

• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2017, 13, 960–987, doi:10.3762/bjoc.13.97

• and one separation step. In the first step, a Friedel–Crafts acylation of isobutylbenzene (1 equiv) and propionyl chloride (1.17 equiv) in the presence of AlCl3 as Lewis acid was carried out in a tubular reactor. The residence time is one minute, and the temperature is maintained at 87 °C. The outlet

Metal-free hydroarylation of the side chain carbon–carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid

• Anna S. Zalivatskaya,
• Dmitry S. Ryabukhin,
• Marina V. Tarasenko,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya,
• Elena V. Grinenko,
• Ludmila V. Osetrova,
• Eugeniy R. Kofanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2017, 13, 883–894, doi:10.3762/bjoc.13.89

• , N4,C-diprotonated forms of oxadiazoles are the electrophilic intermediates in this reaction. Keywords: Friedel–Crafts reaction; hydroarylation; oxadiazoles; superelectrophilic activation; triflic acid; Introduction Oxadiazoles are an important class of heterocyclic compounds and great attention has

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• neurodegenerative diseases and as effective insecticides, fungicides and herbicides. Keywords: biological activity; Diels–Alder reaction; Friedel–Crafts reaction; 1-indanones; Nazarov reaction; Introduction In the last few years, 1-indanone derivatives and their structural analogues have been widely used in

• 11 (X = H/OH) and 2-(trifluoromethyl)acrylic acid (10) as a result of a Friedel–Crafts alkylation. An efficient and scalable one-pot process for the preparation of 1-indanones from benzoic acids has been described by Huang et al. [18]. In this synthesis, acyl chlorides formed in the reaction of

• benzoic acids 15 with thionyl chloride, reacted with ethylene and the resulting intermediates underwent an intramolecular Friedel–Crafts alkylation to form 1-indanones 16 (Scheme 6). Both arylpropionic and 3-arylacrylic acids 17 underwent cyclization in the presence of polyphosphoric and sulfuric acids to

A novel method for heterocyclic amide–thioamide transformations

• Walid Fathalla,
• Ibrahim A. I. Ali and
• Pavel Pazdera

Beilstein J. Org. Chem. 2017, 13, 174–181, doi:10.3762/bjoc.13.20

• heating isatine with malonic acid followed by esterification of the produced quinoline carboxylic acid with methanol in the presence of sulfuric acid at 80 °C for 6 h. 4-Arylphthalazin-1(2H)-ones A7 and A8 [24][25] were prepared by Friedel–Crafts acylation reaction of N-aminophthalimide with either

cis-Diastereoselective synthesis of chroman-fused tetralins as B-ring-modified analogues of brazilin

• Dimpee Gogoi,
• Runjun Devi,
• Pallab Pahari,
• Bipul Sarma and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2016, 12, 2816–2822, doi:10.3762/bjoc.12.280

• Abstract We have synthesized a series of cis-6a,7,8,12b-tetrahydro-6H-naphtho[2,1-c]chromen-6a-ols as B-ring-modified analogues of (±)-brazilin. A completely regio- and cis-diastereoselective intramolecular Friedel–Crafts epoxy–arene cyclization of 1-tetralone-derived glycidyl ethers catalyzed by Brønsted

• studied during the past 15 years [19]. Moreover, on many occasions natural product-like molecules exhibit more potent biological activities than the parent natural products [20]. Meanwhile, the intramolecular Friedel–Crafts epoxy–arene (IFCEA) cyclization has been well-established as a powerful tool for

• diastereoselectivity (Scheme 2, upper panel). Thus, we were concerned about the possibility of getting a mixture of 5 and 9 under the planned IFCEA cyclization of 6. However, a literature survey indicated that cis-diastereoselective synthesis of related tetracyclic molecules via intramolecular Friedel–Crafts