Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• ; indanones; trichloromethyl group; triflic acid; Introduction Superelectrophilic activation of organic compounds under the action of strong Brønsted and Lewis acids is an effective method for the synthesis of various carbocycles and heterocycles, and polyfunctional compounds (see books [1][2] and reviews [3

• conjugated enones afford O,C-diprotonated forms under superelectrophilic activation conditions. These dications can participate in electrophilic aromatic substitution reactions with arenes ([11] and references therein). Recently, we have shown that the reaction of (E)-5,5,5-trichloropent-3-en-2-one [Cl3CCH

• , we initiated this study on transformations of 1-aryl-4,4,4-trichlorobut-2-en-1-ones under superelectrophilic activation conditions (Scheme 1b). The main goals of this work were the investigation of the protonation of CCl3-enones (1-aryl-4,4,4-trichlorobut-2-en-1-ones) by NMR spectroscopy and DFT

AlBr₃-Promoted stereoselective anti-hydroarylation of the acetylene bond in 3-arylpropynenitriles by electron-rich arenes: synthesis of 3,3-diarylpropenenitriles

• Yelizaveta Gorbunova,
• Dmitry S. Ryabukhin and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2663–2667, doi:10.3762/bjoc.17.180

• ]. Recently, we have shown that reactions of 3-arylpropenenitriles (cinnamonitriles, ArCH=CHCN) with arenes (Ar′H) under the superelectrophilic activation by the Brønsted superacid CF3SO3H (TfOH, triflic acid) or the strong Lewis acid AlBr3 result in the formation of 3,3-diarylpropanenitriles (Ar(Ar′)CHCH2CN

Synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

• Andrey I. Puzanov,
• Dmitry S. Ryabukhin,
• Anna S. Zalivatskaya,
• Dmitriy N. Zakusilo,
• Darya S. Mikson,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2417–2424, doi:10.3762/bjoc.17.158

• bond of these oxadiazoles quantitatively resulted in E/Z-vinyl triflates. The reactions of the cationic intermediates have been studied by DFT calculations and the reaction mechanisms are discussed. Keywords: acetylene-oxadiazoles; Friedel–Crafts reaction; hydroarylation; superelectrophilic activation

• the transformations of these heterocyclic compounds in electrophilic media. The main goals of this work were the synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and the study of their reactions with/without arenes under the conditions of superelectrophilic activation by the Brønsted superacid CF3SO3H

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

• superacids or coordination by a Lewis superacid to produce a di- (tri- or higher) cationic species, the study of superelectrophilic activation became a very active area of research [11][12][13]. The acid-catalyzed condensation of ketones and aldehydes with aromatic compounds is known as the hydroxyalkylation

• , superelectrophilic activation of the carbonyl group was achieved for 5-formyl and 5-acetylimidazoles in triflic acid CF3SO3H (TfOH) by Klumpp [19]. It was proposed that the triflic acid initially protonated the imidazole ring and an equilibrium was established with the O-protosolvated form or the dicationic

• reactions exist. Based on our previous studies on the chemistry of heterocycles under superelectrophilic activation [22][23][24], we undertook this research on reactions of benzimidazole derivatives in (super)acids. The main goal of this work was the study of reactions of substituted benzimidazoles 1–8

Generation of 1,2-oxathiolium ions from (arysulfonyl)- and (arylsulfinyl)allenes in Brønsted acids. NMR and DFT study of these cations and their reactions

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov,
• Olesya V. Khoroshilova and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2018, 14, 2897–2906, doi:10.3762/bjoc.14.268

• )allenes 1a,b under superelectrophilic activation with TfOH or AlX3 (X = Cl, Br). The corresponding cations Aa,b generated from 1a,b in TfOH were subjected to quenching with various nucleophiles followed by hydrolysis (Scheme 7). In all the cases, allyl alcohols 7a,b were isolated (see X-ray structure of

• . Reactions of (arylsulfinyl)allenes 1a,b under superelectrophilic activation. Selected 1H and 13C NMR data for cations Aa,b and Ba–h, P1, P2 derived at the protonation of the corresponding allenes at room temperature in TfOH and D2SO4. Selected electronic characteristics of cations Aa, Ba generated from

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

• investigation of their properties are of ongoing interest in chemistry and medicine. Based on our previous works on reactions of cinnamides [24] and 5-styryl-2H-tetrazoles [25] with arenes under superelectrophilic activation with Brønsted or Lewis superacids, we turned our attention towards the hydroarylation

• of the C=C double bond in 5-styryl-substituted oxadiazoles, such as (E)-5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles 1 (Scheme 1). The main goals of the current work were to investigate the reactions of oxadiazoles 1 with different arenes under the conditions of superelectrophilic activation and to

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

• -derived products. Superelectrophilic activation is the generation of highly reactive di-, tri- (or even higher) cationic species by protonation and protosolvation of organic molecules with low nucleophilic Brønsted superacids, such as CF3SO3H (TfOH) or FSO3H [32]. The same activation may be achieved with

• and Lewis superacids. Previously superelectrophilic activation of aldehyde groups was achieved for heteroaromatic aldehydes [34][35][36][37], substituted benzaldehydes and o-phthalic dicarboxaldehyde [38]. Based on these findings, one would expect the activation of an aldehyde group of 5-HMF and 2,5

• diarylmethyl-substituted furans, which are otherwise hardly available molecules [39][40][41][42][43][44][45][46] and used for the synthesis of bioactive compounds [47]. Thus, the superelectrophilic activation of 5-HMF and 2,5-DFF could be of great value for organic synthesis. Results and Discussion The

Reactions of N,3-diarylpropiolamides with arenes under superelectrophilic activation: synthesis of 4,4-diaryl-3,4-dihydroquinolin-2(1H)-ones and their derivatives

• Larisa Yu. Gurskaya,
• Diana S. Belyanskaya,
• Dmitry S. Ryabukhin,
• Denis I. Nilov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 950–956, doi:10.3762/bjoc.12.93

• superelectrophilic activation of the N-formyl group by TfOH in the reaction with benzene resulted in the formation of N-(diphenylmethyl)-substituted dihydroquinolinones. Keywords: alkynes; quinolinones; Friedel–Crafts reactions; superacids; superelectrophilic activation; Introduction Quinoline derivatives are a

• [4][5]. Many of these synthetical protocols are based on alkynes, which are widely used for the preparation of various carbo- and heterocycles [6][7][8][9][10]. Based on our works on the synthesis of 4-arylquinolin-2(1H)-ones from acetylene compounds under superelectrophilic activation conditions [11

• finally cyclized to 4,4-diaryl-3,4-dihydroquinolin-2(1H)-ones 2. It should be noted that quinolinones 3 do not react with arenes with formation of compounds 2 under superelectrophilic activation, and starting materials 3 remain unreacted [12][13]. Such 4,4-diaryl-3,4-dihydroquinolin-2-(1H)-ones 2 are very

Molecular rearrangements of superelectrophiles

• Douglas A. Klumpp

Beilstein J. Org. Chem. 2011, 7, 346–363, doi:10.3762/bjoc.7.45

• isoalkanes in aprotic solvents (SO2, SO2ClF, or CH2Cl2). To account for the observed increasing electrophilic reactivities, Olah proposed the concept of superelectrophilic activation [7]. It was suggested that the superacidic media interacts with the non-bonding electron pairs of the acetyl cation (1), to

• generate a protosolvated superelectrophile (2 or 3, Scheme 1). Protosolvation of the acetyl cation produces an electrophile with increasing dicationic character and consequently superelectrophilic reactivity. Since Olah’s proposal of superelectrophilic activation, the role of dicationic intermediates has

• . Thus, superelectrophiles tend to rearrange by reaction steps similar to monocationic rearrangements. Superelectrophilic activation of the acetyl cation. Ring opening of diprotonated 2-oxazolines. AlCl3-promoted ring opening of isoxaolidine 16. Ring-opening reactions of cyclopropyl derivatives