Visible-light-promoted radical cyclisation of unactivated alkenes in benzimidazoles: synthesis of difluoromethyl- and aryldifluoromethyl-substituted polycyclic imidazoles

• Yujun Pang,
• Jinglan Yan,
• Nawaf Al-Maharik,
• Qian Zhang,
• Zeguo Fang and
• Dong Li

Beilstein J. Org. Chem. 2025, 21, 234–241, doi:10.3762/bjoc.21.15

• CF2HCO2H or PhCF2COOH, along with benzimidazoles bearing unactivated alkenes and PhI(OAc)2 as substrates, and proceeded without the need of any base, metal catalyst, photocatalyst or additive. In total, 24 examples were examined, and all of them successfully underwent cyclization reaction to produce the

• derivatives exhibit improved pharmacokinetic properties [17], which has further sparked interest in their development. Consequently, constructing benzimidazoles bearing the CF2H and PhCF2 groups has garnered significant attention. However, despite this growing interest, only a limited number of research

• groups have reported the direct difluoromethylation/cyclization reaction of benzimidazoles with alkenes for the syntheses of difluoromethylated tricyclic benzimidazoles to date. For example, in 2023, Chen and co-workers pioneered an electrochemical approach for the difluoromethylation and cyclization

Negishi-coupling-enabled synthesis of α-heteroaryl-α-amino acid building blocks for DNA-encoded chemical library applications

• Matteo Gasparetto,
• Balázs Fődi and
• Gellért Sipos

Beilstein J. Org. Chem. 2024, 20, 1922–1932, doi:10.3762/bjoc.20.168

• , showing that N-protection is not mandatory for this transformation. 3-Bromo- and 3-chloroindazoles offered moderate yields (39% and 48% for 2p and 2q, respectively), while 5-substituted 2r was isolated with 82% yield. In contrast to pyrazoles and indazoles, benzimidazoles and imidazoles required the

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ³-iodanes

• Thomas J. Kuczmera,
• Pim Puylaert and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

• detected as a side reaction via mass spectrometry. Vinyl alcohols were also studied, giving carvone (4v) in 74% yield without oxidation of the double bonds. Finally, other heterocyclic benzylic alcohols were investigated, which led to undesired chlorinations in the case of benzimidazoles 3w and 3x and

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• in the presence of sodium metabisulfite (Na2S2O5) [29] to obtain the corresponding substituted benzimidazoles (III) in essentially quantitative yield (Scheme 1). In the absence of Na2S2O5, but under otherwise similar conditions, we obtained in some cases the imines in which one of the amino groups

• condenses with the aldehyde but where the subsequent second condensation and oxidation does not take place, i.e., structures of type IV (Scheme 1), which are known to be converted to benzimidazoles by various oxidants and/or catalysts [30][31][32]. The benzimidazoles were then doubly methylated with

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• system using a benzimidazole sacrificial donor. As we have discussed, examples of recycling benzimidazoles already exist which makes them excellent candidates for donor recycling. In contrast to those developed for water splitting, one of the first visible light-driven Z-scheme for carbon dioxide

• are being developed in non-aqueous solvents. Amines, disulfide-forming thiolates, and NADH derivatives, such as benzimidazoles and acridines, are used as sacrificial donors. Other families of compounds used in other applications such as non-aqueous RFBs, dye-sensitized solar cells, and LOHCs will also

• likely that the same recycling methods could be extended to the rest of the benzimidazole family. Benzimidazoles are being adopted in organic photoreductions [30], and have been shown to increase the efficiency of carbon dioxide reduction systems using ruthenium-based photocatalytic systems [48][72

Synthesis and reactivity of azole-based iodazinium salts

• Thomas J. Kuczmera,
• Annalena Dietz,
• Andreas Boelke and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27

• benzimidazoles gave the expected products 5an–ap in 50–60% yield. The pyrazole-substituted salt 5aq was obtained with 65% yield. Using an electron-rich 5,6-dimethylbenzimidazole substrate yielded dimethylated product 5ar in 85% yield. Unfortunately, even under harsher reaction conditions, the corresponding

One-pot synthesis of 2-arylated and 2-alkylated benzoxazoles and benzimidazoles based on triphenylbismuth dichloride-promoted desulfurization of thioamides

• Arisu Koyanagi,
• Yuki Murata,
• Shiori Hayakawa,
• Mio Matsumura and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 1479–1487, doi:10.3762/bjoc.18.155

• as a promoter afforded various 2-aryl- and 2-alkylbenzoxazoles in moderate to excellent yields under mild reaction conditions. This method could also be applied to the synthesis of benzimidazoles and benzothiazoles. This study presents the first use of triphenylbismuth dichloride to produce

• constructing azoles with an amine functional group at the 2-position, such as benzoxazole or benzoimidazole, but are unsuitable for the syntheses of 2-arylated or 2-alkylated benzoxazoles and benzimidazoles. In fact, only two reports cover the subject. Jackson et al. carried out the intramolecular ring-closure

• -aminophenol with benzimidoyl chloride, which is produced by the desulfurization and chlorination of thioamides promoted by Ph3BiCl2 without a base. The developed protocol is also applied to prepare 2-substituted benzimidazoles using N-tosyl-1,2-phenylenediamines as substrates. Results and Discussion We

Dissecting Mechanochemistry III

• Lars Borchardt and
• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1454–1456, doi:10.3762/bjoc.18.150

• an appropriate oxidant for C–N couplings towards the synthesis of 1,2-disubstituted benzimidazoles and quinazolin-4(3H)-one derivatives under mechanochemical conditions, as evidenced by Mal and co-workers (Scheme 5) [9]. However, the findings within Mechanochemistry III span beyond the synthesis or

DDQ in mechanochemical C–N coupling reactions

• Shyamal Kanti Bera,
• Rosalin Bhanja and
• Prasenjit Mal

Beilstein J. Org. Chem. 2022, 18, 639–646, doi:10.3762/bjoc.18.64

• -Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is a commonly known oxidant. Herein, we report that DDQ can be used to synthesize 1,2-disubstituted benzimidazoles and quinazolin-4(3H)-ones via the intra- and intermolecular C–N coupling reaction under solvent-free mechanochemical (ball milling) conditions. In

• the presence of DDQ, the intramolecular C(sp2)–H amidation of N-(2-(arylideneamino)phenyl)-p-toluenesulfonamides leads to 1,2-disubstituted benzimidazoles and the one-pot coupling of 2-aminobenzamides with aryl/alkyl aldehydes resulted in substituted quinazolin-4(3H)-one derivatives in high yields

• toward the synthesis of 1,2-disubstituted benzimidazoles [39] under mechanochemical (ball milling) conditions (Figure 1a). In addition, the one-pot coupling of 2-aminobenzamides with aryl/alkyl aldehydes in the presence of DDQ resulted in substituted quinazolin-4(3H)-one [40] derivatives (Figure 1b

Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• transformations. For example, bromoacetylenes were demonstrated to add imidazoles, imidazolines [12], and benzimidazoles [13][14] to give vinyl bromides. Sulfonamides reacted with bromoacetylenes to deliver N-bromovinyl-p-toluenesulfonamides that under Heck reaction conditions afforded N-(p-toluenesulfonyl

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• moderate yield with >90% enantioselectivity (Scheme 20c) and tolerable diastereoselectivity (4:1) [73]. The optically enriched benzimidazoles are N-heterocycles which are of great interest as drug-like molecules [75], and exhibit biological activities such as anticancer, antiviral, antifungal, and

• benzimidazoles. In the presence of CPA 7, the corresponding products 65 were obtained with the highest selectivity (up to 96% ee) at full conversion while catalyst CAT 1 (Scheme 21) afforded 65 with up to 94% ee at 96% conversion. The highly substituted axially chiral benzimidazoles 65 were all formed with

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

Synthesis of imidazo[1,5-a]pyridines via cyclocondensation of 2-(aminomethyl)pyridines with electrophilically activated nitroalkanes

• Dmitrii A. Aksenov,
• Nikolai A. Arutiunov,
• Vladimir V. Maliuga,
• Alexander V. Aksenov and
• Michael Rubin

Beilstein J. Org. Chem. 2020, 16, 2903–2910, doi:10.3762/bjoc.16.239

• ], benzimidazoles 6 [40][41], diazines 7 [42][43], or imidazolines 8 (Scheme 1) [44]. We have also shown that a nucleophilic attack on the phosphorylated nitronate species 2 can be carried out with the participation of N-acylhydrazides or thiosemicarbazides to afford the 1,3,4-oxadiazoles 9 [45] and the 1,3,4

Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• ]. Benzimidazoles are an important class of organic materials, and many derivatives of these group are biologically active [6][7][8][9]. The benzimidazole moiety “ […] is isosteric with indole and purine nuclei, which are present in a number of fundamental cellular components and bioactive compounds. Indeed, a

• investigational therapeutic agents, including antitumorals and antivirals […]” [8]. Interestingly, most fluorine-containing benzimidazoles contain the fluorinated substituent either on the aromatic ring or on a side chain connected to the aromatic ring; examples of benzimidazoles containing a fluoroalkyl group

• connected to a nitrogen atom of the imidazole segment are relatively rare. Known examples include benzimidazoles carrying NCF3 [10], NCF2H [11][12][13], NRf (Rf = CF2Cl, CF2Br, CF2CFClH, CF=CFClF) [14][15], and hexafluoroisopropyl groups attached to the nitrogen atom [16]. Recently, we reported a new method

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• , India Department of Physics, S.V.D. College, Kadapa-516003, Andhra Pradesh, India 10.3762/bjoc.16.156 Abstract Natural dolomitic limestone (NDL) is employed as a heterogeneous green catalyst for the synthesis of medicinally valuable benzimidazoles, dihydropyrimidinones, and highly functionalized

• : benzimidazoles; dihydropyrimidinones; highly substituted pyridines; natural dolomitic limestone; ultrasound irradiation; Introduction Nitrogen heterocycles are recognized as “privileged medicinal scaffolds” because these compounds are found in a wide variety of bioactive natural products and pharmaceuticals [1

• ][2][3]. Among them, benzimidazoles, dihydropyrimidinones, and pyridines have emerged as promising and valuable structural units in many pharmaceutical lead compounds (Figure 1) [4][5][6][7][8][9]. Hence, there is a great need for the development of a green and sustainable synthetic route to the

Anthelmintic drug discovery: target identification, screening methods and the role of open science

• Frederick A. Partridge,
• Ruth Forman,
• Carole J. R. Bataille,
• Graham M. Wynne,
• Marina Nick,
• Angela J. Russell,
• Kathryn J. Else and
• David B. Sattelle

Beilstein J. Org. Chem. 2020, 16, 1203–1224, doi:10.3762/bjoc.16.105

• Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, United Kingdom 10.3762/bjoc.16.105 Abstract Helminths, including cestodes, nematodes and trematodes, are a huge global health burden, infecting hundreds of millions of people. In many cases, existing drugs such as benzimidazoles

• (Table 2, Figure 1) [30]. Unfortunately, drug resistance against benzimidazoles 1 and 2 and other anthelmintics have been detected in veterinary parasites, with mutations in the beta-tubulin gene [31][32]. To date there is limited evidence of resistance to benzimidazoles in human STHs [33], although

• . Additionally, the emergence of drug resistance is a concern with some reports of infections that respond poorly to PZQ in areas where there has historically been heavy use of the drug [45]. However, as is the case for benzimidazoles, there is no clear confirmation that clinically relevant praziquantel

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• activation (carbonyl C–H bonds of formamides). Some of the amides or ethers found to be compatible with this method are shown in Scheme 26. A wide range of heteroarenes 114 was also found compatible with this method, including substituted benzothiazole substrates, substituted benzimidazoles, and thiazoles

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• . Subsequently, a range of hybrid molecules, including triazole–benzimidazoles 50–53, triazole–benzothiazole 54, and triazole–benzoxazole 55, was prepared under the above-mentioned conditions (Scheme 8). The benefits of this catalytic system were mild reaction conditions, low catalyst loadings, a diverse set of

Thermal stability of N-heterocycle-stabilized iodanes – a systematic investigation

• Andreas Boelke,
• Yulia A. Vlasenko,
• Mekhman S. Yusubov,
• Boris J. Nachtsheim and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2019, 15, 2311–2318, doi:10.3762/bjoc.15.223

• thermal stability of pyrazoles and indazoles (6–8) in direct comparison to triazoles (2–5) is very likely connected with the lower C/N ratio. Benzimidazoles 9–11 showed increased ΔHdec values (58.5–76.4 kJ/mol) in comparison with pyrazoles 6–8. Broad decomposition peaks (up to 14 °C peak width – see

Synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles: Cs₂CO₃-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium

• Mio Matsumura,
• Yuki Kitamura,
• Arisa Yamauchi,
• Yoshitaka Kanazawa,
• Yuki Murata,
• Tadashi Hyodo,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2019, 15, 2029–2035, doi:10.3762/bjoc.15.199

• University, 1314-1 Shido, Sanuki, Kagawa 769-2193, Japan 10.3762/bjoc.15.199 Abstract The synthesis of benzimidazo[2,1-b]benzoselenoazoles is described. The novel ring-closure reaction of 1-(2-bromoaryl)benzimidazoles with Se powder is promoted by Cs2CO3 (2 equiv) in DMF at 150 °C. Moreover, the obtained

• metal catalyst. We present in this paper the synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles under transition metal-free conditions by the Cs2CO3-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium. Results and Discussion We initially focused our attention on determining the optimal

• 1,2-DCE resulted in inefficient reactions (Table 1, entries 2 and 11–15). Under aerobic conditions, a significant decrease in the yield of product 2a was observed (Table 1, entry 16). We also attempted the cyclization of 1-(2-bromophenyl)benzimidazoles 1a using other chalcogen powders. However, the

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

• -arylmethyl-substituted benzimidazoles, in yields up to 90%. The reaction intermediates, protonated species derived from starting benzimidazoles in TfOH, were thoroughly studied by means of NMR and DFT calculations and plausible reaction mechanisms are discussed. Keywords: benzimidazoles; cations; Friedel

• –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

• superelectrophile. These two kinds of species may react with benzene leading to products of the transformation of the carbonyl group into a diphenylmethyl one (Figure 2) [19]. To the best of our knowledge, no data on the generation of superelectrophilic species from carbonyl-substituted benzimidazoles and their

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• generation of iminyl radical intermediate 31 by homolytic cleavage of the C–N bond which was followed by reductive elimination and oxidation to yield final compound 21. Inspired by the work of Wang et al. [15] who have exploited a Cu(II)-catalyst for the construction of pyrido[1,2-a]benzimidazoles Li and Xie

• carbonate as a base under aerobic conditions. Along with the synthesis of pyrido[1,2-a]benzimidazoles 78, they have reported the synthesis of benzimidazo[1,2-a]quinoline 79 and benzimidazo[1,2-a]isoquinoline 80 in good to excellent yields. They have used differently substituted arylboronic acids 77 as one

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

• in Table 2. Whereas the biological data, for example against S. aureus or MRSA shows a decreased activity for all azaindole derivatives (compare 1 with 27 or 28) as observed for isosteric benzimidazoles [20], an increased activity for all methylated derivatives (compare pairs of 1/3, 27/28, and 29/30

Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Katarzyna Urbaniak,
• Marcin Jasiński,
• Vladyslav Bakhonsky,
• Peter R. Schreiner and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2019, 15, 497–505, doi:10.3762/bjoc.15.43

• adamantylations of some benzimidazoles and imidazoles have already been reported [31], similar reactions with heterocyclic N-oxides have not been published yet. For that reason, in the final part of the study, a preliminary experiment aimed at the O-adamantylation of imidazole N-oxide 7a was carried out under

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• pyridine as an additive (Scheme 6) [46]. Similarly, benzothiazoles also efficiently underwent hydroheteroarylation by using suitable ligands [47]. The reaction was successfully extended to indoles and benzimidazoles 7 bearing a removable 2-pyrimidyl (2-pym) directing group with alkynes at ambient