Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds

• Vasudevan Dhayalan

Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200

• asymmetric reactions and are functional transformations in synthetic organic chemistry. Especially, 1,2,3-triazole-based NHCs are generally more reactive and stronger σ-donors than imidazole or thiazole analogues. Triazolium NHC enhances their ability to stabilize reactive radical intermediates or acyl anion

• , tolerates a variety of functional groups, and offers a wide substrate scope. Under the optimized conditions, Rb2CO3 provided better results than DMAP and Cs2CO3. The acyl azolium complex B was synthesized from acyl imidazole 9 using an NHC and Rb2CO3 as the base. Considering the redox potential of 4CzIPN

Enantioselective radical chemistry: a bright future ahead

• Anna C. Renner,
• Sagar S. Thorat,
• Hariharaputhiran Subramanian and
• Mukund P. Sibi

Beilstein J. Org. Chem. 2025, 21, 2283–2296, doi:10.3762/bjoc.21.174

• method for the enantioselective α-C(sp3) alkenylation of ketones containing imidazole auxiliaries (Scheme 10) [24]. The transformation was catalyzed by a chiral-at-rhodium Lewis acid 42. A variety of ketone electrophiles 40 and alkenyl trifluoroborate nucleophiles 41 were converted to the corresponding α

C2 to C6 biobased carbonyl platforms for fine chemistry

• Jingjing Jiang,
• Muhammad Noman Haider Tariq,
• Florence Popowycz,
• Yanlong Gu and
• Yves Queneau

Beilstein J. Org. Chem. 2025, 21, 2103–2172, doi:10.3762/bjoc.21.165

Photochemical reduction of acylimidazolium salts

• Michael Jakob,
• Nick Bechler,
• Hassan Abdelwahab,
• Fabian Weber,
• Janos Wasternack,
• Leonardo Kleebauer,
• Jan P. Götze and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153

• representative substrate in two steps from benzoyl chloride, imidazole and methyl trifluoromethanesulfonate. In an initial reaction, this species was reacted under photoredox conditions in the presence of [Ir(dF(CF3)ppy)2(dtbpy)]PF6 (2 mol %, dF(CF3)ppy = 3,5-difluoro-2-[5-(trifluoromethyl)-2-pyridine, dtbpy

Enantioselective desymmetrization strategy of prochiral 1,3-diols in natural product synthesis

• Lihua Wei,
• Rui Yang,
• Zhifeng Shi and
• Zhiqiang Ma

Beilstein J. Org. Chem. 2025, 21, 1932–1963, doi:10.3762/bjoc.21.151

• ) and vinyl acetate, affording the corresponding monoacetate. Subsequent reaction with tert-butyldiphenylsilyl chloride (TBDPSCl) and imidazole provided compound 119 in 94% yield over two steps with 97% ee. Next, compound 120 was obtained in six steps from 119. A stereoselective aldol reaction installed

Photoswitches beyond azobenzene: a beginner’s guide

• Michela Marcon,
• Christoph Haag and
• Burkhard König

Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143

• wavelength (P-type) or through thermal back isomerisation (T-type). As a general rule, the absorption can be red-shifted by the choice of electron-donating rings (pyrrole, thiophene), while electron-withdrawing rings (pyridine, pyrimidine, pyrazole, imidazole, thiazole) give the opposite effect [12

• pronounced red-shift of the E-isomer was observed for the pyrrole derivative 66 [81], showing that the hydrogen bond between pyrrole and carbonyl also plays a role (Scheme 21, left). The band separation also provides almost quantitative PSS in both directions. The imidazole derivative 67 (Scheme 21, right

Unique halogen–π association detected in single crystals of C–N atropisomeric N-(2-halophenyl)quinolin-2-one derivatives and the thione analogue

• Mai Uchibori,
• Nanami Murate,
• Kanako Shima,
• Tatsunori Sakagami,
• Ko Kanehisa,
• Gary James Richards,
• Akiko Hori and
• Osamu Kitagawa

Beilstein J. Org. Chem. 2025, 21, 1748–1756, doi:10.3762/bjoc.21.138

• diverse C–N atropisomeric compounds possessing carboxamide, imide, lactam, sulfonamide, indole, pyrrole, imidazole, carbazole and amine skeletons have been reported by many groups [1][2][3][4][5][6][7][8][9]. C–N atropisomers are attractive compounds from the viewpoint of not only synthetic organic

Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade

• Feng Zhou,
• Chuansong Duanmu,
• Yanxing Li,
• Jin Li,
• Haiqing Xu,
• Pan Wang and
• Kai Zhu

Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132

• reagent, demonstrating broad functional group tolerance while revealing that only the N-nitro unit on N1 participates in nitroarene formation [8]. According to Yao et al., SO3H-functionalized imidazole ionic liquids (e.g., [MIMBs]HSO4, 98.1% yield) enabled efficient m-xylene nitration with mitigated

On the aromaticity and photophysics of 1-arylbenzo[a]imidazo[5,1,2-cd]indolizines as bicolor fluorescent molecules for barium tagging in the study of double-beta decay of ¹³⁶Xe

• Eric Iván Velazco-Cabral,
• Fernando Auria-Luna,
• Juan Molina-Canteras,
• Miguel A. Vázquez,
• Iván Rivilla and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2025, 21, 1627–1638, doi:10.3762/bjoc.21.126

• values at the molecular plane are always negative, but the pyrrole ring shows the lowest value. Indeed, if the NICSzz(0) values are considered, a paratropic character is observed at the center of the pyrrole and imidazole rings. The situation is more consistent when the NICS values are computed 1 Å above

3-Aryl-2H-azirines as annulation reagents in the Ni(II)-catalyzed synthesis of 1H-benzo[4,5]thieno[3,2-b]pyrroles

• Julia I. Pavlenko,
• Pavel A. Sakharov,
• Anastasiya V. Agafonova,
• Derenik A. Isadzhanyan,
• Alexander F. Khlebnikov and
• Mikhail S. Novikov

Beilstein J. Org. Chem. 2025, 21, 1595–1602, doi:10.3762/bjoc.21.123

• tested also did not promote the reaction between 1 and 2a, but some of them were found to catalyze the dimerization of azirine 2a to 2H-imidazole 4 (Table 1, entries 6‒9). Imidazole 4 is a known compound that is formed in low yield upon treatment of azirine 2a with FeCl2 in MeCN [20]. To our delight, the

Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Marcin Palusiak,
• Heinz Heimgartner,
• Marta Denel-Bobrowska and
• Agnieszka B. Olejniczak

Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113

• , respectively [2][6]. On the other hand, enolizable imidazole-2-thiones and pyrimidine-2-thione were reported to react with 1a and 1b yielding S,S-dithioacetals as exclusive trapping/insertion products [12] (Scheme 1). Notably, enolizable nitrogen heterocycles such as imidazole and pyrazole, or bicyclic

N-Salicyl-amino acid derivatives with antiparasitic activity from Pseudomonas sp. UIAU-6B

• Joy E. Rajakulendran,
• Emmanuel Tope Oluwabusola,
• Michela Cerone,
• Terry K. Smith,
• Olusoji O. Adebisi,
• Adefolalu Adedotun,
• Gagan Preet,
• Sylvia Soldatou,
• Hai Deng,
• Rainer Ebel and
• Marcel Jaspars

Beilstein J. Org. Chem. 2025, 21, 1388–1396, doi:10.3762/bjoc.21.103

• -15. Strong HMBC correlations observed from H-18 to C-16, C-20 (δH 116.5) and from H-20 to C-18 (δH 133.8) and H-15 to C-16 (see Figure 2) confirmed the presence of a monosubstituted imidazole subunit of histamine linked to the methylene groups at C-16 as evidenced by a two-bond correlation from H-15

High-pressure activation for the solvent- and catalyst-free syntheses of heterocycles, pharmaceuticals and esters

• Kelsey Plasse,
• Valerie Wright,
• Guoshu Xie,
• R. Bernadett Vlocskó,
• Alexander Lazarev and
• Béla Török

Beilstein J. Org. Chem. 2025, 21, 1374–1387, doi:10.3762/bjoc.21.102

• imidazole-based N-heterocyclic carbene (NHC)–CuCl complexes [40]. However, their synthesis is often tainted by the use of toxic reagents and solvents. In addition, when o-phenylenediamine reacts with ketones, the common catalytic methods yield benzodiazepine products [41]. In our case the reaction of o

Synthetic approach to borrelidin fragments: focus on key intermediates

• Yudhi Dwi Kurniawan,
• Zetryana Puteri Tachrim,
• Teni Ernawati,
• Faris Hermawan,
• Ima Nurasiyah and
• Muhammad Alfin Sulmantara

Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91

• alcohols, 34 and ent-34, after recrystallization from hot hexane (100% ee by chiral phase HPLC, yield not reported). These alcohols were then treated with triphenylphosphine and iodine in the presence of imidazole to yield the iodides 35 and ent-35 (Scheme 2). The iodide intermediates were subsequently

• in 96% yield. Hydrolysis of the acetate group in 69 with potassium carbonate followed by treatment with TBDMSCl and imidazole converted it into silyl ether 70. The ester group in 70 was then hydrolyzed using lithium hydroxide, and the resulting acid was coupled with Evans’ chiral oxazolidinone in the

• functionality of 87 was reduced to the corresponding primary alcohol with DIBAL-H and converted to the iodide derivative using Ph3P/I2/imidazole reagents. The resulting iodide was treated with lithiated (R,R)-91 to afford compound 86 in a 76% yield with excellent diastereoselectivity (>99:1 dr). Finally

Investigations of amination reactions on an antimalarial 1,2,4-triazolo[4,3-a]pyrazine scaffold

• Henry S. T. Smith,
• Ben Giuliani,
• Kanchana Wijesekera,
• Kah Yean Lum,
• Sandra Duffy,
• Aaron Lock,
• Jonathan M. White,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2025, 21, 1126–1134, doi:10.3762/bjoc.21.90

• mixtures were separated by silica flash column chromatography, and in some cases, were subsequently separated by HPLC where required. All reactions gave easily isolated product in high purity (≥95%), with yields ranging from 18% to 87%. No ipso-substituted products, and no triazole–imidazole rearrangement

On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals

• Daniel Straub,
• Markus Gross,
• Mona E. Arnold,
• Julia Zolg and
• Alexander J. C. Kuehne

Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80

Sequential two-step, one-pot microwave-assisted Urech synthesis of 5-monosubstituted hydantoins from L-amino acids in water

• Wei-Jin Chang,
• Sook Yee Liew,
• Thomas Kurz and
• Siow-Ping Tan

Beilstein J. Org. Chem. 2025, 21, 596–600, doi:10.3762/bjoc.21.46

• -donating protic group close to the reaction center. Good yields (70–71%) of hydantoins containing heterocyclic groups, such as indole (H2c) and imidazole (H2d) were also achieved. This demonstrates potential application of this protocol in the synthesis of pharmacologically active hydantoin compounds. The

Formaldehyde surrogates in multicomponent reactions

• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Bernhard Westermann

Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45

• tosyl methyl isocyanides [96]. However, when the authors attempted the reaction with 37% aqueous formaldehyde, the reaction did not produce the 1,4-disustituted imidazole 43a but instead the 2-aminooxazoline derivative 44 (Scheme 39). It was proposed that the cycloaddition between formaldehyde and the

• toluenesulfinate moiety, producing the 2-aminooxazoline derivative 44 as the main product. In this report, it was stated that this result can be avoided by replacing formaldehyde with glyoxylic acid (Scheme 40). Using similar reaction conditions, the authors obtained the desired 1,4-disubstituted imidazole

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

• target products in good to excellent yields. Mechanistic studies revealed that the reaction proceeds via a radical pathway. Keywords: cyclization; difluoromethylation; hypervalent iodine; polycyclic imidazole; visible light; Introduction Organofluorine compounds continue to play important roles in

• with CF2HCOOH or PhCF2COOH, and PIDA under additive-, base-, and metal catalyst-free conditions (Scheme 1b). Results and Discussion Initially, 1-(pent-4-en-1-yl)-1H-benzo[d]imidazole (1a), CF2HCOOH, and PIDA were chosen as the template substrates for this radical difluoromethylation and cyclization

• production of the anticipated products in yields ranging from moderate to good (3e–h). Afterwards, we shifted our focus to substrates containing a single imidazole ring and discovered that the radical difluoromethylation and subsequent cyclization of unactivated olefin-containing imidazoles proceeded

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• . From the mechanistic point of view, it is expected that the reaction proceeds via formation of an imine XXXIV between isoxazole carbaldehyde, activated by the copper salt, and 2-aminoazine, which in turn undergoes a non-concerted [4 + 1] cycloaddition involving isonitrile to give the imidazole ring of

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

• present. On the other hand, peptide phosphoric acid C46 appears to work through an alternative mode of enantioinduction, where conformational adaptation presumably limits repulsive interactions. CPA C40 was utilized in the construction of the imidazole ring of axially chiral products 200 (Scheme 59) [89

• determined in the CPA-catalyzed intramolecular enantioselective addition and oxidative aromatization affords the final products 200. The organocatalytic construction of the imidazole ring to provide axially chiral N-arylbenzimidazoles 203 was catalyzed by CPA (R)-C23 (Scheme 60) [90]. It was a reaction of N

Synthesis of the 1,5-disubstituted tetrazole-methanesulfonylindole hybrid system via high-order multicomponent reaction

• Cesia M. Aguilar-Morales,
• América A. Frías-López,
• Nadia V. Emilio-Velázquez,
• Alejandro Islas-Jácome,
• Angelica Judith Granados-López,
• Jorge Gustavo Araujo-Huitrado,
• Yamilé López-Hernández,
• Hiram Hernández-López,
• Luis Chacón-García,
• Jesús Adrián López and
• Carlos J. Cortés-García

Beilstein J. Org. Chem. 2024, 20, 3077–3084, doi:10.3762/bjoc.20.256

• importance of the tert-butyl and cyclohexyl substituents in the imidazole can be deduced. According to the IC50 results presented in Figure 1, it can be seen that all cyclohexyl-substituted derivatives tested show activity. In contrast, those carrying the tert-butyl group are inactive, except for 18i and 18a

Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines

• Dmitriy Yu. Vandyshev,
• Daria A. Mangusheva,
• Khidmet S. Shikhaliev,
• Kirill A. Scherbakov,
• Oleg N. Burov,
• Alexander D. Zagrebaev,
• Tatiana N. Khmelevskaya,
• Alexey S. Trenin and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236

• imidazole nucleophilic center not involved in the first step. This process leads to the formation of alternative final products: imidazo[1,2-a]imidazoles 10 and 12, imidazo[1,5-a]pyrimidines 4, 5, 11 and 14, and imidazo[1,2-a]diazines 13 and 15. The analysis of the spectral data (1H and 13C NMR, 2D NMR

• C-3 of the imidazole core, would not be possible for the alternative imidazopyrimidine system. These results allowed us to reject the structure 11. The lack of correlation in the HMBC spectra between the protons of the amide fragment and the C-5 carbon atom, as well as the presence of cross-peaks of

• the H-5 proton with the C-8a nodal atom and the C-3 imidazole carbon atom, further supports the formation of product 4d. Strong interactions between protons of two methylene groups are the most noticeable features in the NOESY spectrum of the imidazo[1,2-a]pyrimidine 5d. Due to the conformational

5th International Symposium on Synthesis and Catalysis (ISySyCat2023)

• Anthony J. Burke and
• Elisabete P. Carreiro

Beilstein J. Org. Chem. 2024, 20, 2704–2707, doi:10.3762/bjoc.20.227

• reported that imidazole analogs behaved differently due to the ʟ-histidine unit representing a nonphenyl scaffold. Some important data on the bioisosteric modifications of 2-phenethylamine derivatives, focusing on their affinity and core aromatic diversity, were included. In another Review article

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• heteroatoms (nitrogen, sulfur, selenium, tellurium, etc.) as well as redox-active functional groups allows one to vary significantly the biological activity of such compounds. Heterocyclic molecular blocks are widely used in medicinal chemistry [12]. Thiazole, oxadiazole, triazole, imidazole, and other

• activity against the HeLa cancer cell line [22]. 1,2,4-Triazole thioglycoside derivatives have antiviral activity against influenza strains H3N2 and H5N1 [31][32]. The 1,2,4-triazole-3-thione-imidazole hybrids displayed potential antibacterial activity against E. coli, S. aureus [33]. Heterocyclic thione

• , imidazole, thiadiazole, or other fragments [44][45][46][47][48]. Previously, we obtained a series of sterically hindered catechols linked through a sulfide bridge with various polar or low-polar groups [36][49][50][51] and heterocyclic fragments [52] via the Michael addition reaction. Also, we have