Kinetically stabilized 1,3-diarylisobenzofurans and the possibility of preparing large, persistent isoacenofurans with unusually small HOMO–LUMO gaps

• Qian Liu and
• Glen P. Miller

Beilstein J. Org. Chem. 2024, 20, 1099–1110, doi:10.3762/bjoc.20.97

• Acenes are composed of linearly annellated benzene rings. Compared to their non-linearly annellated isomers, acenes possess smaller HOMO–LUMO gaps. This is attributed to their novel electronic structures which manifest that no more than one benzene ring can be drawn with a full aromatic sextet in any

• smaller HOMO–LUMO gaps. Isoacenofurans are composed of linearly annellated benzene rings that terminate with a furan ring. Isoacenofurans and acenes possess isoelectronic π-systems when the total number of rings is the same. Unlike acenes, none of the 6-membered rings in an isoacenofuran possess an

Light on the sustainable preparation of aryl-cored dibromides

• Fabrizio Roncaglia,
• Alberto Ughetti,
• Nicola Porcelli,
• Biagio Anderlini,
• Andrea Severini and
• Luca Rigamonti

Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95

• bromination with NBS in CCl4 yields no more than 30% of the desired 1,3,5-tris(bromomethyl)benzene (4a) [56], due to the concurrent ring bromination [57]. A modified method working in refluxing benzene and benzoyl peroxide initiator was claimed to provide a clean conversion to 4a with very high yields [36][58

• concentrated to dryness to give the crude product. 1,2-Bis(bromomethyl)benzene (1a): white solid, yield: 98%. 1H NMR (400 MHz, 298 K, CDCl3) δ 7.37 (m, 2H), 7.31 (m, 2H), 4.67 (s, 4H) ppm. 1,2-Dibromo-4,5-dimethylbenzene (1b): For the 10-gram scale procedure, see Figure S2 (Supporting Information File 1

• ), brown solid, yield: 93%. Recrystallisation from hot petroleum ether gave the pure product. 1H NMR (400 MHz, 298 K, CDCl3) δ 7.37 (s, 2H), 2.19 (s, 6H) ppm. 1,2-Dibromo-4,5-bis(bromomethyl)benzene (1c): From 1b: chlorobenzene (4.0 mL) was used as the solvent instead of CH2Cl2 (1 mL). Brown solid, yield

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• * level of theory (depicted in Figure 4 and Figure 5). Figure 4 reveals that the HOMOs of 1a–7a are predominantly localized on the π-donor units, such as benzene and naphthalene, with an illustration in the case of 6a. On the contrary, the LUMOs are delocalized across the entire π-systems, while also

Auxiliary strategy for the general and practical synthesis of diaryliodonium(III) salts with diverse organocarboxylate counterions

• Naoki Miyamoto,
• Daichi Koseki,
• Kohei Sumida,
• Elghareeb E. Elboray,
• Naoko Takenaga,
• Ravi Kumar and
• Toshifumi Dohi

Beilstein J. Org. Chem. 2024, 20, 1020–1028, doi:10.3762/bjoc.20.90

• conditions and the use of an equimolar amount of the metal salt (Scheme 2A). Despite the expected advantage, direct synthesis of these diaryliodonium(III) carboxylates are scarce, and these compounds were synthesized by reacting (diacetoxyiodo)benzene and N-functionalized pyrrole in 2,2,2-trifluoroethanol

• (trifluoroacetoxyiodo)benzene was used instead of 1a. Substrate scope of the carboxylic acids and iodosylarenes. a) The reaction was conducted for 4 h. b) 2.0 mL TFE was used. Representative applications of aryl(TMP)iodonium(III) carboxylates. Supporting Information Supporting Information File 2: Further experimental

Carbonylative synthesis and functionalization of indoles

• Alex De Salvo,
• Raffaella Mancuso and
• Xiao-Feng Wu

Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87

• recent achievements on the synthesis and functionalization of indole derivatives via carbonylative approaches. Keywords: carbonylation; functionalization; indole; metal catalyst; organometallic chemistry; Introduction Indole is a heterocyclic compound consisting of a benzene ring fused with a pyrrole

• of amides from 2-alkynylanilines by using TFBen (benzene-1,3,5-triyl triformate) as a CO source, Pd(OAc)2, DPEPhos (bis[(2-diphenylphosphino)phenyl] ether), and DIPEA (N,N-diisopropylethylamine) in MeCN. After 24 h, Pd(OAc)2 and AlCl3 were added to promote a selective cyclization reaction [14]. The

• reaction took place in the presence of Pd(OAc)2 (2 mol %), 1,10-phenantroline (4 mol %) under 1 bar of CO at 110 °C in DMF. After the right time, six products were isolated, while, in three cases, when the benzene ring was meta-substituted, a regioisomeric mixture was obtained. The regioselectivity was

Synthesis and properties of 6-alkynyl-5-aryluracils

• Ruben Manuel Figueira de Abreu,
• Till Brockmann,
• Alexander Villinger,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 898–911, doi:10.3762/bjoc.20.80

• ring instead of a benzene moiety. This was demonstrated by the introduction of thiophene (5r) and furan (5t) to the uracil structure. The molecules 5n and 5o could not be obtained, due to decomposition during the reaction. The structure of 5a was confirmed by X-ray crystallographic analysis. Crystals

(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• well as the impact they have on the physiochemical and biological properties of pharmaceuticals and agrochemicals. Keywords: bioisosteres; drug discovery; meta-benzene; ortho-benzene; Introduction The logical and iterative modification of the structure of a drug candidate is a critical part of the

• ]. The direct replacement of substituted benzenes in drug candidates with saturated benzene bioisosteres is a popular approach to this task [11][12][13][14]. Substitution of a mono-substituted benzene (a phenyl group) is relatively straightforward [11][13][15]. More particular attention must be paid to

• benzenes that have more than one substituent; for example, the ortho-, meta-, or para- relative substitution of a disubstituted benzene should ideally be replicated in the saturated bioisostere to ensure ligand–protein binding is conserved through the bioisosteric swap. Bioisosteres of para-substituted

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• unfortunately data in the absence of ZnCl2 was not provided by the authors. ZnCl2 has been previously reported as a catalyst for hydrochlorination reactions, notably in the case of cyclooctene (25) with HCl in benzene (Scheme 5D) [47]. The use of ZnCl2 as a catalyst for hydrochlorinations dates back to a patent

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• a parallel direction, as the bulky -OMe groups are located outside the tweezer’s cavity to avoid steric hindrance with each other. When protonated, the pyridinium group acts as a hydrogen-bond donor for the two methoxy groups and triggers the rotation of the respective benzene rings along with the

Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives

• Nahed Ketata,
• Linhao Liu,
• Ridha Ben Salem and
• Henri Doucet

Beilstein J. Org. Chem. 2024, 20, 427–435, doi:10.3762/bjoc.20.37

• palladium-catalyzed direct intermolecular arylation, followed by a direct intramolecular arylation step. As the C–H bond activation of several benzene derivatives remains very challenging, the preparation of fluoranthenes from 1,8-dibromonaphthalene via Suzuki coupling followed by intramolecular C–H

• with 1,2-dihalobenzenes. To our knowledge, this reaction has not yet been described, but 9-arylphenanthrenes can be synthesized by reacting 1-bromo-2-(1-phenylthenyl)benzene with bromobenzenes as coupling partners in the presence of a palladium catalyst [41]. We have observed that the reaction of 3

• simplest involves 1,8-dibromonaphthalene with a double C–H bond functionalization of benzene derivatives. This method, which employs Pd-catalyzed intermolecular and then intramolecular activation of arene C–H bonds, tolerates several useful substituents on the arene, such as fluoro, chloro, methoxy

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

• efficiency would not diminish even after 3 cycles [99]. Several substituted indoles, aldehydes and ketones reacted in good yields (74–98%), with ketones requiring longer reaction rates of 3 hours, due to their lower reactivity. The electron-donating or withdrawing effects of the substituents of the benzene

• two electron-donating substituents on the benzene ring. However, no ketones or aliphatic substrates managed to exhibit sufficient reactivity. The nanoAg-Pt silicate could be easily recovered by a simple filtration with methanol, allowing it to be reused for several catalytic cycles, before it was

• amount further resulted in a lower conversion. Next, the generality of the method was explored by employing several aliphatic and aromatic aldehydes, as well as substituted indoles, in various positions of the benzene ring. N-Substituted indoles displayed the lowest reactivity, providing yields around 75

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

• this situation. Acenes are a class of aromatic compounds composed of linearly fused benzene rings, which can be regarded as the narrowest graphene nanoribbons. They are highly promising p-type organic semiconductors, but suffer from insolubility and instability leading to dimerization and/or

• precursors inherently limits the applicability of these reactions to the synthesis of π-CPCs containing linearly-fused benzene rings in their core scaffold (i.e., at least an anthracene pattern), or to the deprotection of peripheral benzene rings. To reach a wider variety of structures, novel synthetic

• , this class of compounds is prone to valence isomerization via 6π-electrocyclization leading to the formation of heteroatom-containing norcaradiene, and oxepine has been shown to exist in equilibrium with its valence isomer benzene oxide [37]. In contrast with the parent oxepine, which is isolable at

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• quinolines, at the benzene ring, and the resulting nitro compounds could potentially be subjected to further transformations, including nucleophilic substitution of nitro groups. Indeed, under the action of a small excess of the nitrating mixture, dipyridoacenaphthene 5 undergoes double nitration at

• decided to carry out its oxidation to 12 by the traditional method – the action of chloranil in boiling benzene or chloroform (in the latter, the solubility of the components is somewhat better, although the temperature of the process decreases). At the end of the synthesis, the reaction mass was treated

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• and C=O bonds of the indoxyl groups are somewhat longer than typical double bonds of these types (Figure 3). On the contrary, the C–N bonds in indigo are much shorter than the single C–N bond in pyrrolidine, while the lengths of the C–C bonds in the fused benzene rings are approximately the same as in

• benzene (Figure 3). This indicates that in addition to structure I, which is traditionally used to depict indigo, intraionic resonance structures II and III with single C–O bonds and double C=N bonds make a pronounced contribution in the ground state of indigo (Figure 3) [13][14]. In the excited state

• , the resonance structures II and III with separated charges become predominant, while both benzene rings remain fully aromatic. The indigo dye contains two heterocyclic indole ring systems, which are connected through a double bond and have 22 π-electrons [16][17]. However, only 10 π-electrons are

Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs

• Amina Moutayakine and
• Anthony J. Burke

Beilstein J. Org. Chem. 2024, 20, 193–204, doi:10.3762/bjoc.20.19

• –Lam/carbonylative cyclization After disclosing the optimal conditions for the Chan–Lam coupling, we screened different varieties of o-phenylenediamine derivatives. Overall, the o-phenylenene substrates bearing electron-donating substituents on the benzene ring proceeded smoothly under these conditions

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• dried at 80 °C in vacuo (0.1 Torr, 1 h)) was added. The mixture was stirred at room temperature (≈20 °C) until complete consumption of the starting material (TLC monitoring, Rf = 0.10 (7), Rf = 0.57 (2), benzene/EtOAc 9:1). The reaction mixture was concentrated under reduced pressure, the residue was

• triturated with anhydrous benzene (5 mL), and the extract was filtered through a PTFE microfilter (0.45 μm, 13 mm diameter, Iso-Disk, Supelco). The filtrate was concentrated under reduced pressure and the residue was dried in vacuo to give 2 as a colorless solid (118.8 mg, 73%). [α]D19 −87.4 (c 4.3, CHCl3

• ); Rf 0.57 (benzene/EtOAc 9:1); 1H NMR (300 MHz, CDCl3, δ, ppm, J, Hz) 2.25 (dd, J3a,3e = 13.9, J3a,4 = 11.7, 1H, H-3a), 2.82 (dd, J3e,3a = 13.9, J3e,4 = 4.8, 1H, H-3e), 3.71 (s, 3H, OMe), 3.96 (ABq, ΔδAB = 0.03, JAB = 15.0, 2H, CH2Cl), 4.09 (ABq, ΔδAB = 0.02, JAB = 15.4, 2H, CH2Cl), 4.12 (dd, J9a,9b

Synthesis of the 3’-O-sulfated TF antigen with a TEG-N₃ linker for glycodendrimersomes preparation to study lectin binding

• Mark Reihill,
• Hanyue Ma,
• Dennis Bengtsson and
• Stefan Oscarson

Beilstein J. Org. Chem. 2024, 20, 173–180, doi:10.3762/bjoc.20.17

• glycosylation reactions. The 3’-sulfate was finally introduced through tin activation in benzene/DMF followed by treatment with a sulfur trioxide–trimethylamine complex in a 66% yield. Keywords: regioselective sulfation; thioglycoside donors; Thomsen–Friedenreich antigen; Introduction In a collaboration

• observable sulfation taking place, the tin-activation step was suspected to be the root of the problem. To rectify this, similar to Malleron et al., 1 was refluxed, in a Dean–Stark set-up, with Bu2SnO in benzene/DMF (5:1, v/v) [32]. The solvent in the receiver was drained after 24 hours and the benzene was

• -galactopyranoside sodium salt (2): Compound 1 (1.24 g, 2.29 mmol) and Bu2SnO (645 mg, 2.75 mmol) were placed under N2 together. Dry benzene/DMF (380 mL, 5:1, v/v) was added and the reaction was refluxed at 125 °C using a Dean–Stark apparatus. After 24 hours, the solvent in the receiver was drained, and the benzene

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• CH2Cl2 (CD2Cl2, 1H = 5.32 ppm, 13C = 54.00 ppm), deuterated DMSO ((CD3)2SO, 1H = 2.50 ppm, 13C = 39.53 ppm), deuterated acetone ((CD3)2CO, 1H = 2.05 ppm, 13C = 29.84 ppm), or deuterated benzene (C6D6, 1H = 7.16 ppm, 13C = 128.39 ppm) were used as solvents and internal references. Chemical shift values

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

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

• ; biphenylene; [N]phenylenes; polycyclic aromatic compounds; Introduction Acenes represent an important category of carbon-rich polycyclic aromatic hydrocarbons (PAHs) characterized by the presence of linearly fused benzene rings [1][2]. Investigating the electronic properties of acenes is essential for

• benzene rings connected with a four-membered ring, is a highly intriguing compound in terms of its structure. It possesses a planar configuration and consists of 4n π-electrons, rendering it antiaromatic. However, despite being antiaromatic, biphenylene is more stable than other known antiaromatic

• 12 topologies (Figure 2) [26][27][28][29][30]. In [N]phenylene structures, the presence of a formally antiaromatic four-membered ring leads to the localization of π-electrons on the benzene rings [31]. Despite this phenomenon, the oligomer series demonstrates a decreasing band gap, indicating the

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

• small singlet–triplet splitting and a fair photoluminescence quantum yield (PLQY). The optimized organic light-emitting diode (OLED) based on 13 wt % CPC doped in 1,3-bis(9H-carbazol-9-yl)benzene (mCP) as host exhibited maximum current efficiency, power efficiency, and external quantum efficiency (EQE

• . Similarly, the strongest TADF intensity was obtained for the neat films of compound 9 and of compound 9 molecularly dispersed in the host 1,3-bis(N-carbazolyl)benzene (mCP; Figure 3c,d and Figure S3a in Supporting Information File 1). Low-energy absorption bands of molecular mixtures of compounds 6–9 and

• , 116.60, 114.11, 112.38, 99.13, 92.84, 86.01, 34.93, 31.83, 31.65, 30.67, 29.07, 28.89, 22.60, 14.12; Anal. calcd for C130H132N10S2: C, 82.24; H, 7.01; N, 7.38; found: C, 81.59; H, 7.13; N, 6.95. 4,4’,4’’-((Benzene-1,3,5-triyltris(ethyne-2,1-diyl)tris(benzene-4,1-diyl))tris(2,6-bis(3,6-di-tert-butyl-9H

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

• catalyst for obtaining the product of insertion into the NH bond of the heterocycle. An effort to obtain the N–H insertion product with dibenzoazepine proved fruitless. Instead, the product of insertion into the C–H bond of the activated benzene ring (9z) was isolated in moderate yield. The chemo- and

Charge carrier transport in perylene-based and pyrene-based columnar liquid crystals

• Alessandro L. Alves,
• Simone V. Bernardino,
• Carlos H. Stadtlober,
• Edivandro Girotto,
• Giliandro Farias,
• Rodney M. do Nascimento,
• Sergio F. Curcio,
• Thiago Cazati,
• Marta E. R. Dotto,
• Juliana Eccher,
• Leonardo N. Furini,
• Hugo Gallardo,
• Harald Bock and
• Ivan H. Bechtold

Beilstein J. Org. Chem. 2023, 19, 1755–1765, doi:10.3762/bjoc.19.128

• . In 1-iso, only the two hexagonal imide groups affect the HOMO/LUMO localization, whereas the pentagonal central imide group is little affected. In 2-iso, both pentagonal are relevant to the HOMO/LUMO localization, whereas the two terminal benzene rings are little affected. The cartesian coordinates

Unprecedented synthesis of a 14-membered hexaazamacrocycle

• Anastasia A. Fesenko and
• Anatoly D. Shutalev

Beilstein J. Org. Chem. 2023, 19, 1728–1740, doi:10.3762/bjoc.19.126

• and therefore more conformationally rigid compounds. Previously, the unintentional preparation of two polyunsaturated 1,2,4,8,9,11-hexaazamacrocycles fused with two benzene or two pyrazole rings has been reported [39][40]. In particular, Dolzhenko et al. attempted to reproduce the synthesis of 4-imino

• the starting material. This compound was prepared according to the described regioselective method [42] based on the reaction of malononitrile with triethyl orthoformate followed by subsequent treatment of the obtained dinitrile 2 with benzaldehyde methyl hydrazone in benzene, conc. aqueous HCl in

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• -withdrawing terminal acceptor units, and careful selection of solvents and annealing processes have also been demonstrated as potential solutions to improve charge transport and refine the device fabrication processes. You et al. found that the position of alkoxy side chains on the pendant benzene rings

• significantly influenced the performance of Qx2 acceptors. Three variants of Qx2, i.e., Qx7 and Qx8 were synthesized with alkoxy side chains located at the meta and para positions of the pendant benzene rings. Qx7 exhibited efficient exciton dissociation, good electron-transporting ability, and a PCE of 5.07

• study raises a concern regarding the performance of dyes with tert-butyl substituted DPQ acceptors, either containing benzene (Qx74) or thiophene (Qx75) as a π-conjugation linker and their benzotriazole analogue. While the incorporation of the Qx enhances the interaction between the donor and acceptor

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

• ) (30 nm)/tris(4-carbazoyl-9-ylphenyl)amine (TCTA) (10 nm)/TPECNZ (60 nm)/1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) (40 nm)/LiF (1 nm)/Al (100 nm), in which ITO and Al served as anode and cathode, respectively (Figure 7a). Herein, HAT-CN and LiF were used as the hole- and electron