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

• –Crafts reaction; triflic acid; Introduction Imidazoles and benzimidazoles are important heterocyclic scaffolds in pharmaceuticals and agrochemicals [1][2][3][4][5][6][7][8][9][10]. They also have applications in the fields of dyes, chemo-sensing, and fluorescent materials [3]. (Benz)imidazoles are a

• . 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

• 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

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

• 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

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

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

• ) 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

• Friedel–Crafts reaction of N-Boc-isatin imines 3 with 6-hydroxyquinolines 48 promoted by the cinchona alkaloid-derived thiourea 40 [68]. The process was performed in toluene at room temperature to give the corresponding chiral 3-amino-2-oxindoles 49 bearing a quinoline moiety in moderate to excellent

• with 1 and 2-naphthols catalyzed by a cinchona alkaloid-derived thiourea. Friedel–Crafts reactions of N-alkoxycarbonyl-isatin imines with 1 and 2-naphthols catalyzed by a cinchona alkaloid-derived squaramide. Friedel–Crafts reaction of N-Boc-isatin imines with 6-hydroxyquinolines catalyzed by a

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

• Friedel–Crafts reaction on enantiomerically labelled [2H1]benzyl fluoride. Results and Discussion Highly enantiomerically enriched 7-[2H1]-(R)-benzyl fluoride ((R)-1) was synthesised in two steps from benzaldehyde (2), as described previously [11]; the procedure is summarised in Scheme 1. Aldehyde 2 was

• nucleophile, coupled with the stronger hydrogen bond donor in the Friedel–Crafts reaction allows the solvent-separated ion-pair mechanism to predominate, significantly eroding the stereointegrity of the biarylmethane products 10. However, the products were not racemic, showing that the nucleophilic attack

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

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

• temperature. Results and Discussion All the sugar-based porous organic polymers (SugPOP-1–3) were synthesized by Friedel–Crafts reaction using FDA as an external cross-linker in a similar way. The preparation routes are shown in Scheme 1. Using benzylated monosaccharides as monomers and FDA as the cross

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

• form 1-indanones 18 in good yields (60–90%) (Scheme 7) [19]. A one-step synthesis of 1-indanones 22 through the NbCl5-induced Friedel–Crafts reaction, has been described by Barbosa et al. in 2015 [20]. The reaction was carried out using 3,3-dimethylacrylic acid (19), aromatic substrate 20 and highly

• –Crafts reaction. These compounds are stable at room temperature, easily prepared, functionalized, handled and purified. Thus, the intramolecular Friedel–Crafts acylation of aromatics with Meldrum's acid derivatives 65, catalyzed by metal trifluoromethanesulfonates such as Sc(OTf)3, Dy(OTf)3, Yb(OTf)3

Superelectrophilic activation of 5-hydroxymethylfurfural and 2,5-diformylfuran: organic synthesis based on biomass-derived products

• Dmitry S. Ryabukhin,
• Dmitry N. Zakusilo,
• Mikhail O. Kompanets,
• Anton A.Tarakanov,
• Irina A. Boyarskaya,
• Tatiana O. Artamonova,
• Mikhail A. Khohodorkovskiy,
• Iosyp O. Opeida and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 2125–2135, doi:10.3762/bjoc.12.202

• 5-HMF and 2,5-DFF were characterized by NMR spectroscopy in TfOH and studied by DFT calculations. These reactions show possibilities of organic synthesis based on biomass-derived 5-HMF and 2,5-DFF. Keywords: 2,5-diformylfuran; Friedel–Crafts reaction; 5-hydroxymethylfurfural; superacids; zeolites

• -(chloromethyl)furfural (1b) and 5-(bromomethyl)furfural (1c), both of which are also promising biomass-derived products [58][59], were reacted with benzene under the action of various acids (Table 3). In all cases 5-(phenylmethyl)furfural (3a) as Friedel–Crafts reaction product was obtained. Thus, only the

Hydroxy-functionalized hyper-cross-linked ultra-microporous organic polymers for selective CO₂ capture at room temperature

• Partha Samanta,
• Priyanshu Chandra and
• Sujit K. Ghosh

Beilstein J. Org. Chem. 2016, 12, 1981–1986, doi:10.3762/bjoc.12.185

• polymers (HCPs) are a subclass of this type of porous materials. Recently, hyper-cross-linked MOPs are emerged as a new subclass, synthesized by hyper-cross linking of basic small organic building blocks by Friedel–Crafts reaction in the presence of the Lewis acid FeCl3 (as catalyst) and formaldehyde

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• , Luo and Cheng were able to catalyze an enantioselective Friedel–Crafts reaction between indole 136 and α-substituted acrolein 137 (Scheme 31). Acroleins containing a benzyl α-substituent performed best in the reaction with 2-methylindole (72–95% yield, 93.5:6.5 to 97:3 er). Alkyl and alkenyl

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• with arylboronic [132][133][134], arylbismuth [135], and arylsilicon [136] reagents. Although carbocations react with arenes through electrophilic aromatic hydrogen substitution in a Friedel–Crafts reaction, the potential for metal cations to participate in similar chemistry has been far less widely

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• external Brønsted acid. Proposed transition state TS7 for the Friedel–Crafts reaction of indole and α,β-unsaturated acyl phosphonates catalyzed by ent-4. Possible transition states TS8 and TS9 in the asymmetric addition of indoles 2 to the β,γ-unsaturated α-ketoesters 26 catalyzed by ent-4. Transition

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

• Laura A. Bryant,
• Rossana Fanelli and
• Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

• the two enantiomers of 32 will react more rapidly with nitromethane in the presence of the cupreidine catalyst CPD-33. As these enantiomers equilibrate via 35 in the presence of the catalyst, a dynamic kinetic asymmetric reaction occurs (Scheme 9b). Friedel–Crafts reaction Pedro and co-workers have

• utilized a 9-OH benzoyl derivatised cupreine CPN-38 to effect a Friedel-Crafts reaction of 2-naphthols 36 with benzoxathiazine 2,2-dioxides 37 (Scheme 10). These cyclic imides, derived from salicylic aldehydes, have a rigid structure which prevents E/Z-isomerization, allowing for greater control over the

• . A cupreidine derived catalyst induces a dynamic kinetic asymmetric transformation. Cupreine derivative 38 has been used in an organocatalytic asymmetric Friedel–Crafts reaction. Examples of 6’-OH cinchona alkaloid catalyzed processes include: (a) Deng’s addition of dimethyl malonate into

Mycothiol synthesis by an anomerization reaction through endocyclic cleavage

• Shino Manabe and
• Yukishige Ito

Beilstein J. Org. Chem. 2016, 12, 328–333, doi:10.3762/bjoc.12.35

• reduction, and intramolecular Friedel–Crafts reaction [29][30] (Scheme 2). In particular, the reaction of pyranosides bearing acetyl substituents on the carbamate groups showed complete anomerization [32]. We expected that anomerization via endocyclic cleavage would be useful for mycothiol synthesis

Hydroquinone–pyrrole dyads with varied linkers

• Hao Huang,
• Christoffer Karlsson,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 89–96, doi:10.3762/bjoc.12.10

• also investigated (vide infra), but did not produce satisfactory results. Settambolo et al. [20] reported a synthetic route starting from an acylation of pyrrole by phenylacetyl chloride via a Friedel–Crafts reaction, followed by reduction by NaBH4, and elimination to give the vinylpyrrole product

Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid

• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Anna Gajda,
• Tadeusz Gajda,
• Anna Makal,
• Arnaud Brosseau and
• Rémi Métivier

Beilstein J. Org. Chem. 2015, 11, 2451–2458, doi:10.3762/bjoc.11.266

• observed features of solid-state emission of this compound (vide suppra). Conclusion We demonstrated the feasibility of the Friedel–Crafts reaction with 1-(isothiocyanato)alkylphosphonates by using pyrene as an arene. The pyrenyl thioamidoalkylphosphonates formed in this reaction can be readily transformed

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

Triazol-substituted titanocenes by strain-driven 1,3-dipolar cycloadditions

• Andreas Gansäuer,
• Andreas Okkel,
• Lukas Schwach,
• Laura Wagner,
• Anja Selig and
• Aram Prokop

Beilstein J. Org. Chem. 2014, 10, 1630–1637, doi:10.3762/bjoc.10.169

• with classical organic acylation reactions (Friedel–Crafts reaction, esterification, amide synthesis, Scheme 1). Some of these complexes have been used as organometallic gelators [19][20], as a novel class of cytostatic compounds [26], and catalysts for unusual radical cyclizations [27][28][29][30][31

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

• sequence as shown in Scheme 27-ii [82]. Firstly, a Friedel–Crafts reaction produced the para-substituted phenol in 42% yield. Then, the phenol group was transformed in diethyl aryl phosphate with an AT reaction in 99% yield. Finally, the reduction of the phosphate was achieved in 74% yield. Similar

New hydrogen-bonding organocatalysts: Chiral cyclophosphazanes and phosphorus amides as catalysts for asymmetric Michael additions

• Helge Klare,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2014, 10, 224–236, doi:10.3762/bjoc.10.18

• defined geometry. Introducing a new motif, Shea et al. have synthesized achiral tridentate (thio)phosphorus triamides and assessed their catalytic activity relative to the established (m-(CF3)2-Ph)2thiourea [18]. In the Friedel–Crafts reaction of N-methylindole with β-nitrostyrene and the Baylis–Hillman