Palladium-catalyzed regioselective C1-selective nitration of carbazoles

• Vikash Kumar,
• Jyothis Dharaniyedath,
• Aiswarya T P,
• Sk Ariyan,
• Chitrothu Venkatesh and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2025, 21, 2479–2488, doi:10.3762/bjoc.21.190

• are ubiquitous and privileged heterocyclic scaffolds in various functional organic materials and naturally occurring products. Although extensive efforts have focused on developing synthetic strategies toward carbazole derivatives, direct regioselective functionalization of the carbazole core remains

• valuable platform for the selective functionalization of carbazoles, offering potential applications in optoelectronics, functional organic materials, and related areas while contributing to the advancement of C–H activation methodologies. Keywords: C–H activation; carbazole; catalysis; nitration

• ; palladium; Introduction Carbazole represents an important heterocyclic scaffold that is broadly present in many natural products, biologically active motifs, as well as optoelectronic and functional materials [1][2][3][4][5][6][7][8]. By virtue of its substantial application in various fields, significant

Conformational effects on iodide binding: a comparative study of flexible and rigid carbazole macrocyclic analogs

• Guang-Wei Zhang,
• Yong Zhang,
• Le Shi,
• Chuang Gao,
• Hong-Yu Li and
• Lei Xue

Beilstein J. Org. Chem. 2025, 21, 2369–2375, doi:10.3762/bjoc.21.181

• work represents one of the earliest comparative studies on the anion-binding behaviors of carbazole-based structural analogs, demonstrating that a flexible macrocycle markedly improves iodide binding affinity via an induced-fit mechanism. The flexible analog PBG exhibits a 22.78-fold higher

• fluorescence quenching efficiency upon iodide binding compared to the rigid WDG (KPBG/KWDG = 22.78), demonstrating its potential as a highly sensitive optical probe and offering a novel strategy for engineering dynamic supramolecular receptors. Two carbazole-based macrocyclic probes, PBG (flexible benzene ring

• ; carbazole macrocycles; conformational selection; induced-fit; supramolecular chemistry; Introduction Macrocyclic compounds have garnered significant attention in supramolecular chemistry and anion recognition owing to their tunable cavity geometries and binding capabilities [1][2][3][4][5][6][7][8

Pathway economy in cyclization of 1,n-enynes

• Hezhen Han,
• Wenjie Mao,
• Bin Lin,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173

• synthetic value of this method. In 2017, the Liu group established a precise control over cyclization sequences of 1,2-diphenylacetylenes by modulating the nitrogen-substitution patterns, enabling divergent syntheses of benzo[a]carbazole and indeno[1,2-c]quinoline derivatives (Scheme 9) [16]. When the

• nitrogen atom was substituted with strong electron-withdrawing groups, a nucleophilic attack to gold(I)-activated alkyne generated intermediate 38, with subsequent 6-endo-trig cyclization affording benzo[a]carbazole 39 (Scheme 9, path a). Conversely, the activated alkyne was attacked by enol ether to yield

• intermediate 40 when using substrates with unsubstituted nitrogen. Concurrent oxygen-involved cyclization then furnished indeno[1,2-c]quinoline 41 (Scheme 9, path b). This work established a pathway-controlled strategy for efficient access to benzo[a]carbazole and indeno[1,2-c]quinoline derivatives. In 2019

Thiadiazino-indole, thiadiazino-carbazole and benzothiadiazino-carbazole dioxides: synthesis, physicochemical and early ADME characterization of representatives of new tri-, tetra- and pentacyclic ring systems and their intermediates

• Gyöngyvér Pusztai,
• László Poszávácz,
• Anna Vincze,
• András Marton,
• Ahmed Qasim Abdulhussein,
• Judit Halász,
• András Dancsó,
• Gyula Simig,
• György Tibor Balogh and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2220–2233, doi:10.3762/bjoc.21.169

• -hexahydro[1,2,3]thiadiazino[6,5-a]carbazole 1,1-dioxide (3e) has been identified as a promising central nervous system drug candidate for pharmacological testing and eventual further structure–activity optimization. Experimental Compounds 5a, 5b, 7a–j, (E)-9a, (E)-9b, 3a–j, 10a, 10b are new and

• off and washed with EtOAc (3 × 5 mL). The organic phase was washed with water (5 mL) and brine (5 mL), dried over MgSO4 and evaporated to give crude products 3, which were purified by flash chromatography. 2,4-Dimethyl-2,7,8,9,10,11-hexahydro[1,2,3]thiadiazino[6,5-a]carbazole 1,1-dioxide (3e

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

• benzo[a]carbazole (a very important scaffold in the pharmaceutical industry) from the commercially available 2-phenylindole and bio-renewable 1-hydroxypropan-2-one (acetol) using a sulfone-containing Brønsted acidic medium as catalyst. The process was applied to a number of substituted 2-phenylindoles

Solar thermal fuels: azobenzene as a cyclic photon–heat transduction platform

• Jie Yan,
• Shaodong Sun,
• Minghao Wang and
• Si Wu

Beilstein J. Org. Chem. 2025, 21, 2036–2047, doi:10.3762/bjoc.21.159

• light-harvesting carbazole units with photoresponsive azobenzene units in a unique macromolecular architecture (Figure 4c) [48]. The resulting cross-linked polycarbazole structure led to a high solar thermal storage capacity of 179.9 J/g and an extended half-life at 60 °C, increasing from 7 min for the

• subject to CC BY 4.0. (b) Schematic illustration of diacetylene monomer photopolymerization and the conjugated polydiacetylene structure. Figure 4b was redrawn from [47]. (c) Photoisomerization of a conjugated azobenzene polymer with a carbazole backbone. Figure 4c was redrawn from [48]. Linear azobenzene

Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• ][21][22][23]. In addition to benzene-based systems, pyridine-embedded aza[1n]metacyclophanes have been synthesized by Wang [24]. Despite these advances, N-doped chiral macrocycles incorporating extended π-conjugated moieties remain largely underexplored. To date, only a few examples, carbazole-based

• % and 90%, respectively. For MC2, four C–C bonds are formed between the dichlorobenzene units and tert-butylphenyl groups, generating two dihydroindolo[2,3-b]carbazole subunits. In contrast, there is only one newly formed C–C bond between the dichlorobenzene unit and one pyrene moiety for MC1

• planar dihydroindolo[2,3-b]carbazole subunits orienting upwards with a dihedral angle of 75° and two pyrene units downwards (Figure 2b). Besides, the central cavity is highly symmetric, and the shortest diameters are determined to be 4.34 Å and 4.99 Å, respectively. In contrast to MC2, MC3 shows an

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

Convenient alternative synthesis of the Malassezia-derived virulence factor malassezione and related compounds

• Karu Ramesh and
• Stephen L. Bearne

Beilstein J. Org. Chem. 2025, 21, 1730–1736, doi:10.3762/bjoc.21.135

• neurological disorders [7] and possibly other non-skin diseases [5]. These fungi, especially M. furfur, convert tryptophan into various alkaloid indoles such as malassezione (1), malassezin (2), which cyclizes to indolo[3,2-b]carbazole (3), other related indolo[3,2-b]carbazoles (4–7), pityriarubins (8–10), and

Wittig reaction of cyclobisbiphenylenecarbonyl

• Taito Moribe,
• Junichiro Hirano,
• Hideaki Takano,
• Hiroshi Shinokubo and
• Norihito Fukui

Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107

• peripherally modified CBBC derivatives have also been prepared and were shown to have fascinating properties [17][18][19][20][21]. For example, carbazole-substituted donor–acceptor-type CBBC derivatives exhibit both efficient circularly polarized luminescence (CPL) and thermally activated delayed fluorescence

Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications

• Meng Qiu,
• Jing Du,
• Nai-Te Yao,
• Xin-Yue Wang and
• Han-Yuan Gong

Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106

• -hexabenzo[7]helicene 3 with a carbazole core, which emits at 595/628 nm (PLQY = 0.40), displays |gabs| = 2.98 × 10−3, and achieves a BCPL of 32.5 M−1 cm−1 [16]. In 2025, Babu’s group synthesized two regioisomeric π-extended azahelicenes, 4a and 4b, which differ in the position of attachment to the carbazole

• external stimuli, modular synthetic accessibility, and strong CPL performance render them ideal candidates for applications in molecular sensing, stimuli-responsive switches, and next-generation CPL-active devices. In 2021, Ema’s group reported the synthesis of carbazole-based azahelicenes 11a–e via

• engineering redox-switchable chiral luminophores. In 2024, the same research group expanded on this redox-responsive platform by constructing a polycationic open-shell cyclophane 22, comprising carbazole-embedded aza[7]helicene subunits [36]. Compound 22 displays intense fluorescence (ΦF = 0.99

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

• the hole will reside on the mesityl and phenyl units (HDMO) and the electron resides on the PyBTM core (SOMO) (see Figure 4b). Instead of pyridine also carbazole (Cz) units have been coupled to produce N-carbazolyl-bis(2,4,6-trichlorophenyl)methyl radicals (CzBTM) (see Figure 5a). ϕ is highest at λem

• compounds. Breaking of the symmetry for the |D1⟩ transition by incorporating a donor moiety, leads to enhanced intensity as reflected by growing absorption coefficients ε with increasing donor strength (see Table 1). Replacing one of the phenyl rings for carbazole in triarylmethyl radical leads to much

• chemical investigations have also brought forth that the dihedral angle between the TTM radical plane and the carbazole donor increases when exciting the molecule from the D0 ground state to the excited D1 state. In the D1 state the Cz is aligned almost perpendicular to the TTM plane, which will stabilize

Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts

• Katy Medrano-Uribe,
• Jorge Humbrías-Martín and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76

• offers unique features, including twisted structures, reduced π–π stacking, and enhanced reverse intersystem crossing rates, becoming a better donor compared to fully planar compounds as carbazole (c). Similarly, 5H-dibenz[b,f]azepine (IMD, b) has been incorporated into D–A–D structures, showing

• . Additionally, we aim to evaluate the unique effect of the TBA donor unit (a) compared to other donors. We next synthesized diverse D–A structures employing common nitrogen-based compounds widely used in materials chemistry like carbazole (c), diphenylamine (d), and phenoxazine (e). Furthermore, we wanted to

Recent advances in the electrochemical synthesis of organophosphorus compounds

• Babak Kaboudin,
• Milad Behroozi,
• Sepideh Sadighi and
• Fatemeh Asgharzadeh

Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61

• decomposition leads to the generation of O₂, the primary oxygen source in the reaction process. A radical process was proposed in the reaction. Diphenylphosphine oxide and carbazole radicals were formed via anodic oxidation in the presence of a base, followed by a coupling reaction to give the final P–N product

• -withdrawing groups such as –Cl, –Br, and –CO2Me. It was observed that carbazole derivatives with an extended conjugated system showed enhanced reactivity. Like the above P–N coupling mechanism, the reaction proceeded by an anodic oxidation of iodide to iodine followed by a reaction with dialkylphosphine oxide

• to give I–P(O)(R)2. The exact mechanism of this coupling reaction is not yet fully understood; however, the possibility of direct radical cross-coupling between the nitrogen radical derived from carbazole and the phosphoryl radical intermediate cannot be completely ruled out. In another

Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• have been calculated and have indicated that this latter could be a viable candidate for use in photoredox catalysis. Additionally, its measured excited-state lifetime (τ = 5.5 ns) is similar to those of other widely used organic photocatalysts, such as carbazole derivatives, further supporting its

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

• carbazole 223 or indole 225. The reactions provided excellent enantioselectivities and good yields and the best results were achieved with methyl or chlorine substituents in position 3 of the naphthyl ring. Dicarbazoles are generally useful as OLED materials [97]. For this reason, the authors decided to

Synthesis, characterization, and photophysical properties of novel 9‑phenyl-9-phosphafluorene oxide derivatives

• Shuxian Qiu,
• Duan Dong,
• Jiahui Li,
• Huiting Wen,
• Jinpeng Li,
• Yu Yang,
• Shengxian Zhai and
• Xingyuan Gao

Beilstein J. Org. Chem. 2024, 20, 3299–3305, doi:10.3762/bjoc.20.274

• studies, revealing that their photophysical behavior can be affected by the different substituents in the donor carbazole group. Keywords: carbazole; D−A−D type; noble-metal-free system; 9‑phenyl-9-phosphafluorene oxide; photophysical properties; Introduction π-Conjugated molecular materials containing

• acceptor group in TADF emitters, indicating great potential for the development of highly efficient TADF molecules. In 2019, Nishida and co-workers prepared 5 D–A–D-type PhFlOP derivatives with electron-donating diarylamine or carbazole moieties in positions 2 and 8. They conducted optical and

• access to PhFlOP-based TADF emitters. Additionally, the design of TADF emitters with the PhFlOP acceptor moiety and the carbazole donor moiety is lacking structural diversity. Herein, we present a 5-step synthesis of several novel D−A−D-type PhFlOP derivatives with substituted carbazole groups as donors

Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

• Connor R. M. MacDonald and
• Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

• -assembly across length scales using a combination of SANS and cryo-TEM, as well as other characterisation techniques. To investigate how the change in capping group changed the self-assembly of diphenylalanine, indole-FF, and carbazole-FF (F = phenylalanine) were characterised by SAXS. While both indole-FF

• and carbazole-FF were shown to have fibre radii that were quantifiable by SAXS, the model fit to the indole-FF showed the length to exceed the q range measured. Cryo-TEM was used to corroborate the presence of such fibres, and though they cannot prove the modelled length’s accuracy, they were able to

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• steric hindrance along the pyrene–carbazole bond than that along the anthracene–carbazole one. To predict the appropriate diameters of SWNTs, the spherical cavity sizes were calculated by considering van der Waals radii of all the atoms. The cavity size of Cu-nanobrackets 1b (11.83 Å) is 2.09 Å larger

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

Synthesis of N-acyl carbazoles, phenoxazines and acridines from cyclic diaryliodonium salts

• Nils Clamor,
• Mattis Damrath,
• Thomas J. Kuczmera,
• Daniel Duvinage and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 12–16, doi:10.3762/bjoc.20.2

• fluorophors, previously shown to exhibit strong organic phosphorescence when mixed with specific additives [1][2][3][4][5]. Carbazole units are also found in drugs and natural products. They are also used in electrochemistry and as reagents in transamidation reactions [6][7][8][9][10][11][12]. The traditional

• method to produce this versatile N-acyl carbazole motif involves combining 9H-carbazoles with acyl chlorides or similar activated acyl derivatives in the presence of a base (Scheme 1a) [13][14]. As an alternative, acyl carbazoles can be synthesized through step-wise metal-catalysed C–X-amidations

• [33][34]. Results and Discussion Initially, we investigated the synthesis of N-acyl carbazole by treatment of diaryliodonium salt 1a with valeramide using Cu(I) catalysts [18]. The results are shown in Table 1. In the first experiments in p-xylene at 120 °C with DMEDA as N,N-ligand, only modest

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions

• Karolis Leitonas,
• Brigita Vigante,
• Dmytro Volyniuk,
• Audrius Bucinskas,
• Pavels Dimitrijevs,
• Sindija Lapcinska,
• Pavel Arsenyan and
• Juozas Vidas Grazulevicius

Beilstein J. Org. Chem. 2023, 19, 1867–1880, doi:10.3762/bjoc.19.139

• emitter based on a pyridine-3,5-dicarbonitrile scaffold (to serve as an electron acceptor) directly linked to a carbazole moiety (to serve as an electron donor) was reported by the groups of Dong and Zhang in 2015 [4]. 2,6-Di(9H-carbazol-9-yl)-4-phenylpyridine-3,5-dicarbonitrile (CPC) showed an extremely

• )-4-(4-bromophenyl)pyridine-3,5-carbonitrile (4) was obtained by the interaction of 3,6-di-tert-butyl-9H-carbazole with compound 3 in THF/DMF solution. The ethynylphenyl-substituted pyridine 5 was synthesized by Sonogashira coupling of 4 with ethynyltrimethylsilane in the presence of PdCl2(PPh3)2 and

• transfer from the donor to the acceptor. The absorption spectrum of REF is included in Figure 2a for comparison. Compounds 6–9 are characterized by similar absorption bands also caused by electron transfer from the 3,6-di-tert-butyl-9H-carbazole units to the pyridine-3,5-dicarbonitrile moiety. The number

Thienothiophene-based organic light-emitting diode: synthesis, photophysical properties and application

• Recep Isci and
• Turan Ozturk

Beilstein J. Org. Chem. 2023, 19, 1849–1857, doi:10.3762/bjoc.19.137

• layers are composed of various aromatic π-conjugated small molecules/polymers including thiophene, anthracene, carbazole, and triphenylamine [9][10][11][12][13]. Thienothiophenes are two annulated thiophene rings having four isomers, among which the most widely used isomer is thieno[3,2-b]thiophene (TT

N-Boc-α-diazo glutarimide as efficient reagent for assembling N-heterocycle-glutarimide diads via Rh(II)-catalyzed N–H insertion reaction

• Grigory Kantin,
• Pavel Golubev,
• Alexander Sapegin,
• Alexander Bunev and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 1841–1848, doi:10.3762/bjoc.19.136

• pyrazole derivatives (including indazole), benzimidazole, 1,2,3-triazole, indole, carbazole, indoline, quinazoline, and isoquinoline. Nevertheless, many heterocyclic motifs still remain beyond the attention of researchers. For example, glutarimides that incorporate tetrazole and 1,2,4-triazole substituents

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• –donor (D–A–D)-type molecule and its application as a non-doped emitter in an organic light-emitting diode (OLED). The fluorophore TPECNz contains naphtho[2,3-c][1,2,5]thiadiazole (Nz) as a strong acceptor unit symmetrically functionalized with N-(4-(1,2,2-triphenylvinyl)phenyl)carbazole as a donor and

• twist angle between the D and A units, a strong electron deficiency of the Nz unit, and electron-donating and hole-transporting natures of carbazole, TPECNz exhibits a strong deep red emission (λem = 648 nm) with a high fluorescence quantum yield of 96%, outstanding thermal property (Tg = 236 °C), and

• energy gap between HOMO/LUMO hybrid orbits and drive fluorescence emission to longer wavelengths [48][49]. In this molecular design, the strong electron-deficient naphtho[2,3-c][1,2,5]thiadiazole (Nz) [13][50][51] as an acceptor and the strong electron-donating carbazole [52] as a donor unit were used in