Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules

• Wei Liu and
• Xiaoyu Yang

Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145

• terminal aromatic rings [17]. Despite lacking asymmetric stereogenic centers, this nonplanar scaffold exhibits intrinsic P/M chirality due to the helical arrangement of the π-extended skeleton. Renowned for their high thermal stability and structural rigidity, chiral helicenes have emerged as prominent

Synthesis of optically active folded cyclic dimers and trimers

• Ena Kumamoto,
• Kana Ogawa,
• Kazunori Okamoto and
• Yasuhiro Morisaki

Beilstein J. Org. Chem. 2025, 21, 1603–1612, doi:10.3762/bjoc.21.124

• oligomers using planar chiral tetrasubstituted [2.2]paracyclophane as chiral crossing units were prepared, in which π-extended conjugated systems were folded in either two or three places. The oligomers exhibited good optical properties such as PL and CPL properties with good ΦPL values (>0.6) and |glum

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

• fluorescence (TADF), and chiral sensing. Notably, recent developments have yielded π-extended, structurally robust, and stimuli-responsive azahelicenes exhibiting record-high dissymmetry factors (|gabs| and |glum|), elevated CPL brightness (BCPL), and efficient integration into CPL-OLEDs and redox-switchable

• -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

• signals. This study presents a novel approach to constructing stable, redox-switchable chiral luminophores based on extended azahelicene architectures, offering broad potential for molecular electronics and spintronic devices. In 2024, Qiu’s group synthesized π-extended diaza[7]helicenes 23a–f

Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes

• Bartłomiej Pigulski

Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99

• "formal" or "true" azulene subunits. However, one of the key objectives here is to highlight the differences between these structural types and provide a clear distinction between benzenoid structures with azulene-like linkers and molecules that can be considered “true” aromatic π-extended azulenes. This

• synthesis of π-extended azulene was the non-benzenoid isomer of pyrene published by Ward and co-workers (Scheme 1) [31]. Cyclohept[bc]acenaphthylene (2) was obtained from a partially saturated precursor 1 via dehydrogenation using palladium on carbon. However, the reaction carried out at 300 °C gave 2 as a

• by Jutz and Kirchlechner in 1966 (Scheme 3) [36]. Condensation between phenalene 15 and pentafulvene 16 gave pentafulvene 17. Pentafulvene 17 was finally subjected to Ziegler–Hafner reaction in quinoline at 180 °C, resulting in the π-extended azulene 18 in 60% yield. A similar synthetic strategy was

Selective monoformylation of naphthalene-fused propellanes for methylene-alternating copolymers

• Kenichi Kato,
• Tatsuki Hiroi,
• Seina Okada,
• Shunsuke Ohtani and
• Tomoki Ogoshi

Beilstein J. Org. Chem. 2025, 21, 1183–1191, doi:10.3762/bjoc.21.95

• display good solubility in CHCl3 and THF and adsorption properties for CO2 gas. Results and Discussion Selective monoformylation Initially, we tried introducing formyl groups into a fully π-fused [4.3.3]propellane via organometal species, which had been effective for functional π-extended systems [57][58

Supramolecular assembly of hypervalent iodine macrocycles and alkali metals

• Krishna Pandey,
• Lucas X. Orton,
• Grayson Venus,
• Waseem A. Hussain,
• Toby Woods,
• Lichang Wang and
• Kyle N. Plunkett

Beilstein J. Org. Chem. 2025, 21, 1095–1103, doi:10.3762/bjoc.21.87

• systems, these macrocycles display dynamic behavior even in the absence of extra anions, with monomers swapping between macrocycles to participate in dynamic covalent chemistry. As a demonstration of even higher supramolecular assemblies, we also showed π-extended HIMs enable the co-assembly of

• macrocycle and not to the electrophilic, yet oxygen-rich, core of the macrocycle. (A) Our previous work: Assembly and disassembly of phenylalanine hypervalent iodine macrocycles (Phe HIM) through anion coordination. (B) Another work on π-extended hypervalent iodine macrocycle and their supramolecular

Efficient synthesis of fluorinated triphenylenes with enhanced arene–perfluoroarene interactions in columnar mesophases

• Yang Chen,
• Jiao He,
• Hang Lin,
• Hai-Feng Wang,
• Ping Hu,
• Bi-Qin Wang,
• Ke-Qing Zhao and
• Bertrand Donnio

Beilstein J. Org. Chem. 2024, 20, 3263–3273, doi:10.3762/bjoc.20.270

• expand this chemistry, enabling access to new π-extended molecular systems that might be challenging to synthesize through conventional synthetic routes. This dual focus highlights the study’s potential to advance both the design of functional materials and the development of innovative synthetic

Copper-catalyzed yne-allylic substitutions: concept and recent developments

• Shuang Yang and
• Xinqiang Fang

Beilstein J. Org. Chem. 2024, 20, 2739–2775, doi:10.3762/bjoc.20.232

• ). Preliminary mechanistic studies have ruled out the 1,3-sigmatropic shift, indicating that the reaction proceeds through a nucleophilic substitution–annulation process of a reactive π-extended copper-allenylidene intermediate (Scheme 43). At the same time, Qi and Xu et al. [79] also realized the dearomative

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

Electrocatalytic hydrogenation of cyanoarenes, nitroarenes, quinolines, and pyridines under mild conditions with a proton-exchange membrane reactor

• Koichi Mitsudo,
• Atsushi Osaki,
• Haruka Inoue,
• Eisuke Sato,
• Naoki Shida,
• Mahito Atobe and
• Seiji Suga

Beilstein J. Org. Chem. 2024, 20, 1560–1571, doi:10.3762/bjoc.20.139

• more π-extended aniline was easily obtained in a high yield. Reduction of quinolines to tetrahydroquinolines The electrochemical reduction of quinolines was performed using a PEM reactor. First, several different cathode catalyst were examined for the reduction of quinoline (6a) (Table 5). Because 4.0

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• ” is particularly interesting, since the as-prepared π-extended structures can undergo in-depth structural characterization and electronic investigations in situ at the single molecule scale, thanks to scanning probe microscopy and spectroscopy. The synthetic route relying on O-extrusion was thus

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

Beilstein J. Org. Chem. 2023, 19, 1895–1911, doi:10.3762/bjoc.19.141

• -dibora-2,5-cyclohexadiene structure (Scheme 16) in addition to a π-extended linear POA (Scheme 17) [50]. The preparation of v- and z-shaped POAs 77 and 78 was carried out starting from 2-bromobiphenylene (74). Initial steps involved ortho-directed lithiation and subsequent treatment with Me3SiCl

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• incorporated at the porphyrin periphery and different metal ions in the porphyrin core to modulate ground-state and excited-state characteristics of easily accessible meso-tetraarylporphyrins. Some of these π-extended tetrapyrrolic macrocycles have emerged as potential candidates in photodynamic therapy and

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• regioselectively at 0 °C, affording the desired π-extended [7]helicene 35 and [9]helicene 37 in 76 and 84% yields, respectively. Single-crystal structures of racemic 35 and 37 revealed the P/M enantiomers repectively, and the P/M racemization barriers of 35 and 37 were determined as 42.4 and 41.6 kcal/mol

• , respectively by DFT calculation. The enantiopure isomers of the π-extended helicenes were evaluated as excellent circularly polarized luminescence (CPL) emitters with a glum of 7.44 × 10−3 for 37, which is around 10-fold higher than 35. Chiral “HBC-dimers” and “HBC trimers” The combination of two or more HBCs

• . Wang and co-workers constructed double π-extended undecabenzo-[7]helicene 125, which composed of five HBC units and 186 sp2 carbon atoms [53]. As shown in Scheme 15, a hexaphenylbenzene with four alkyne substitutions was constructed initially. A Sonogashira coupling from 122 to 123, followed by a Diels

Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine

• Saika Izumi,
• Prasannamani Govindharaj,
• Anna Drewniak,
• Paola Zimmermann Crocomo,
• Satoshi Minakata,
• Leonardo Evaristo de Sousa,
• Piotr de Silva,
• Przemyslaw Data and
• Youhei Takeda

Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48

• , the one-less number of donor units in the molecular scaffold led to lower solubility in organic solvents and thermal stability, presumably due to the less steric hindrance around the π-extended conjugated acceptor unit with the unsymmetric molecule structure. The OLEDs fabricated with the D–A emitter

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• . Monothienylisoindigos bearing π-extended electron-donor backbones. Role of fluorination and the molecular weight on OSC efficiency on the base of the bithiopheneisoindigo series. Trithiopheneisoindigo polymers with variation in the substituent structure. Polymeric thienyl-linked bisisoindigos for OSCs. Isoindigo

A straightforward conversion of 1,4-quinones into polycyclic pyrazoles via [3 + 2]-cycloaddition with fluorinated nitrile imines

• Greta Utecht-Jarzyńska,
• Karolina Nagła,
• Grzegorz Mlostoń,
• Heinz Heimgartner,
• Marcin Palusiak and
• Marcin Jasiński

Beilstein J. Org. Chem. 2021, 17, 1509–1517, doi:10.3762/bjoc.17.108

• considerable attention of other groups [18][19] and recently has been applied for the preparation of some π-extended pyrazole derivatives, which exhibited promising biological activity [20]. In a series of our recent publications, efficient syntheses of fluoromethylated five- and six-membered N,S-heterocycles

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• ]helicene 12 was equal to 2.92 eV [42]. The Egopt values for its π-extended analogs were 2.45 eV (10a), 2.76 eV (10b) and 2.85 eV (10c), suggesting a higher HOMO and lower oxidation potential, which are typically desired characteristics when designing organic materials. Unfortunately, for all azine-fused [6

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

• Liliia Moshniaha,
• Marika Żyła-Karwowska,
• Joanna Cybińska,
• Piotr J. Chmielewski,
• Ludovic Favereau and
• Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

• materials, this strategy has so far remained relatively unexplored [27]. As a part of our ongoing research on π-extended electron-deficient oligopyrroles [13][28][29][30][31], we have recently reported that Pd(II)-mediated double C–H activation can be a useful tool for conversion of 1,n-dipyrrolylalkanes

One-pot synthesis of dicyclopenta-fused peropyrene via a fourfold alkyne annulation

• Ji Ma,
• Yubin Fu,
• Junzhi Liu and
• Xinliang Feng

Beilstein J. Org. Chem. 2020, 16, 791–797, doi:10.3762/bjoc.16.72

• an efficient method to develop π-extended aromatic hydrocarbons with cyclopenta moieties. Keywords: alkyne annulation; cyclopenta-fused polycyclic aromatic hydrocarbons; nonplanarity; peropyrene; regioselectivity; Introduction Significant efforts have been recently devoted to the synthesis of

Efficient synthesis of 3,6,13,16-tetrasubstituted-tetrabenzo[a,d,j,m]coronenes by selective C–H/C–O arylations of anthraquinone derivatives

• Seiya Terai,
• Yuki Sato,
• Takuya Kochi and
• Fumitoshi Kakiuchi

Beilstein J. Org. Chem. 2020, 16, 544–550, doi:10.3762/bjoc.16.51

• multiarylated anthraquinone derivatives [16][17][18][19][20]. Using this method, we have synthesized various π-extended aromatic compounds such as multiarylated acenes [16][18][20], dibenzo[h,rst]pentaphenes and dibenzo[fg,qr]pentacenes [19]. In the course of our reaction development, it was found that an

Synthesis of triphenylene-fused phosphole oxides via C–H functionalizations

• Md. Shafiqur Rahman and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2020, 16, 524–529, doi:10.3762/bjoc.16.48

• synthesis of π-extended phospholes. In this respect, our attention focused on the fusion of phosphole with triphenylene, which represents one of the most common disc-like PAH motifs in organic materials chemistry [19][20][21][22][23][24][25]. Herein, we report on the synthesis of triphenylene-fused

• strong blue fluorescence in solution. The absorption and emission profiles of the π-extended phosphole oxide revealed their characteristics as hybrids of 2,3-dialkoxytriphenylene and 1-phenyl-2,3-dialkylbenzo[b]phosphole. We anticipate that the key intermediate of the present synthesis, 3, and related

• benzo[b]phospholes accessible by the three-component assembly hold promise for further explorations inot novel π-extended phosphole derivatives. Examples of functional molecules based on π-extended phospholes. ORTEP drawings of compound 8a (thermal ellipsoids set at 50% probability). a) top view; b

Identification of optimal fluorescent probes for G-quadruplex nucleic acids through systematic exploration of mono- and distyryl dye libraries

• Xiao Xie,
• Michela Zuffo,
• Marie-Paule Teulade-Fichou and
• Anton Granzhan

Beilstein J. Org. Chem. 2019, 15, 1872–1889, doi:10.3762/bjoc.15.183

• ), the absorption spectra of the dyes are blue-shifted with respect to the prototype dye 1a. Conversely, strongly electron-donating (1b, 1d) or π-extended (1k, 1Þ) Ar units lead to bathochromic shifts of absorption bands (Table 1 and Figure 4A). The influence of the heterocyclic core is equally important

Synthesis and characterization of π–extended “earring” subporphyrins

• Haiyan Guan,
• Mingbo Zhou,
• Bangshao Yin,
• Ling Xu and
• Jianxin Song

Beilstein J. Org. Chem. 2018, 14, 1956–1960, doi:10.3762/bjoc.14.170

• 10.3762/bjoc.14.170 Abstract A π-extended “earring” subporphyrin 3 was synthesized from β,β′-diiodosubporphyrin and diboryltripyrrane via a Suzuki–Miyaura coupling and following oxidation. Its Pd complex 3Pd was also synthesized and both of the compounds were fully characterized by 1H NMR, MS and X-ray

• 3Pd is further red-shifted and more intense. Keywords: aromaticity; earring subporphyrin; π-extended; supramolecular chemistry; Findings Since its first synthesis in 2006 [1][2], subporphyrin, the lowest homolog of porphyrins, has received considerable attention [3][4][5][6][7][8] due to its 14π

• cavities π-extended “earring” porphyrins through the aforementioned Suzuki–Miyaura coupling reaction and subsequent oxidation [38]. In this case β,β′-dibromo/tetrabromoporphyrins and diboryltripyrrane were applied as reactants. We discovered that both the π-extended “earring” porphyrins and the