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

• -catalyzed annulative π-extension of 1,8-dibromonaphthalene for the preparation of fluoranthenes in a single operation has been investigated. With specific arenes such as fluorobenzenes, the Pd-catalyzed double functionalization of C–H bonds yields the desired fluoranthenes. The reaction proceeds via a

• tuned, or enables them to be linked to other useful units [1]. There are several synthetic routes to fluoranthene derivatives, but in most cases several steps are required [2][3][4][5]. Over the past two decades, the Pd-catalyzed C–H arylation of a wide variety of arenes has led to a revolution in the

• synthesis of polyaromatic compounds [6][7][8][9][10][11][12]. Since the seminal results of Fagnou et al. in 2006 on the Pd-catalyzed C–H arylation of polyfluorobenzenes [13][14][15][16], several groups have described conditions enabling the direct intermolecular Pd-catalyzed arylation of arenes [17]. In

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• oxyalkylation product 28. Li and co-workers described the activation of NHPI esters towards SET using a Lewis acid catalyst, allowing for the functionalization of styrene radical acceptors with nucleophiles that do not necessarily engage in hydrogen-bonding interactions, such as electron-rich (hetero)arenes [47

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

• ultimate elimination of chalcogen fragments upon thermal activation, photoirradiation and electron exchange. Keywords: arenes; chalcogens; extrusion; fused-ring systems; precursor approach; Introduction π-Conjugated polycyclic compounds (π-CPCs), including polycyclic aromatic hydrocarbons and their

Nucleophilic functionalization of thianthrenium salts under basic conditions

• Xinting Fan,
• Duo Zhang,
• Xiangchuan Xiu,
• Bin Xu,
• Yu Yuan,
• Feng Chen and
• Pan Gao

Beilstein J. Org. Chem. 2024, 20, 257–263, doi:10.3762/bjoc.20.26

• introduced a pioneering method for synthesizing air- and moisture-stable arylthianthrenium salts [11]. This novel approach involves the utilization of tetra-fluorothianthrene sulfoxide (TFT=O) or thianthrene sulfoxide (TT=O), which react with arenes under mild conditions, exhibiting exclusive

• regioselectivity. Significant advancements in the synthesis of arylthianthrenium salts have prompted a growing interest in their utilization as versatile precursors for the conversion of C–H bonds in arenes into C–C/X bonds through transition-metal-catalyzed cross-coupling processes [12][13][14][15][16][17][18][19

• -stage C–H functionalization of arenes, Wickens’s group has introduced an oxidative alkene aziridination strategy that relies on thianthrenation of an alkene under electrochemical conditions [27]. Subsequently, cyclopropanation, [28] aziridination, [29] allylic C–H functionalization, [30][31] transition

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• reactions. Highly nucleophilic arenes like 1,3,5-trimethoxybenzene react easily under mild conditions and result in a stabilized benzylic cation in acidic conditions, allowing a second intramolecular Friedel–Crafts reaction involving the aryl substituent of the substrate. These reactions are favored by π

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

• Kan Tang,
• Megan R. Brown,
• Chad Risko,
• Melissa K. Gish,
• Garry Rumbles,
• Phuc H. Pham,
• Oana R. Luca,
• Stephen Barlow and
• Seth R. Marder

Beilstein J. Org. Chem. 2023, 19, 1912–1922, doi:10.3762/bjoc.19.142

• dimers reduce halides that have reduction potentials less cathodic than ca. −2 V vs ferrocenium/ferrocene, especially under UV photoexcitation (using a 365 nm LED). In the case of benzyl halides, the products are bibenzyl derivatives, whereas aryl halides are reduced to the corresponding arenes. The

• to initiate the coupling of aryl halides and arenes [5]. However, even relatively easily reduced organic halides have sufficiently cathodic reduction potentials (e.g., ca. −1.6 V and −1.8 vs ferrocenium/ferrocene (FeCp2+/0) for diethyl bromomalonate [6] and 4-iodotoluene, see Table 2, respectively

• synthesize by other methods, whereas aryl halides afford dehalogenated arenes. One example also demonstrates that the approach may have utility for selectively dehalogenating compounds containing different halogens. The photoacceleration of these reactions appears to occur through photocleavage of the dimers

Complexes of resorcin[4]arene with secondary amines: synthesis, solvent influence on “in-out” structure, and theoretical calculations of non-covalent interactions

• Waldemar Iwanek

Beilstein J. Org. Chem. 2023, 19, 1525–1536, doi:10.3762/bjoc.19.109

• Waldemar Iwanek Bydgoszcz University of Science and Technology, Faculty of Chemical Technology and Engineering, Seminaryjna 3, 85-326 Bydgoszcz, Poland 10.3762/bjoc.19.109 Abstract Resorcin[4]arenes (R[4]A) are macrocyclic compounds with a cavity structure. Despite a relatively small cavity

• ; Introduction Resorcin[4]arenes are macrocyclic compounds with a cavity structure formed from resorcinol and aldehydes [1]. Of particular significance is their crown conformation, which stems from the presence of 8 hydroxy groups on the upper rim and a hydrophobic cavity [2]. This property plays an important

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• succeeded in synthesizing various diaryl(alkyl) sulfides 5 through the sulfenylation of unactivated arenes 4 with an electrophilic sulfur reagent in the presence of a palladium catalyst (Scheme 3) [45]. In the second phase, dibenzothiophene derivatives 6 were obtained via subsequent intramolecular arylation

• substitution to provide C2,C3-disulfenylated product 66 (Scheme 28). In the same year, Sutherland and Dodds disclosed a protocol for the C–H bond thioarylation of electron-rich arenes 4 like anisoles, acetanilides, phenols, and N-heterocycles in the presence of Fe(III) Lewis acid and ionic liquid [BMIM]NTf2 as

• 102 were obtained in moderate to excellent yields with good to excellent enantioselectivities (Scheme 42) [76]. It should be noted that the authors did not define the exact role of the organocatalyst in the reaction mechanism. Transition-metal-free C–H sulfenylation of electron-rich arenes 103 by N

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• conjugated enones afford O,C-diprotonated forms under superelectrophilic activation conditions. These dications can participate in electrophilic aromatic substitution reactions with arenes ([11] and references therein). Recently, we have shown that the reaction of (E)-5,5,5-trichloropent-3-en-2-one [Cl3CCH

• =CHC(=O)Me] with arenes in Brønsted superacid TfOH (triflic acid, CF3SO3H) furnishes 3-methyl-1-trichloromethylindenes (Scheme 1a) [11]. Based on NMR analysis in TfOH and theoretical DFT calculations, it has been found that the reaction proceeds through an intermediate formation of the O-protonated

• form of the starting compound [Cl3CCH=CHC(=OH+)Me]. The presence of two strong electron-withdrawing substituents, the trichloromethyl group (CCl3) and a protonated carbonyl (C(OH+)Me), at the carbon–carbon double bond makes this O-protonated species electrophilic enough to react with arenes (Scheme 1a

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• carboxylation of acidic arenes and heteroarenes has been reported by Cazin, Nolan and co-workers [90]. In this context, it was found that a combination of [(IPr)CuOH] (3 mol %) with CsOH in THF afforded the best results (Scheme 68), whereas the SIPr, IMes, and SIMes-based NHC–Cu complexes were found to be less

• alkenylate a variety of electron-rich as well as electron-deficient (hetero)arenes. Of the three imidazolylidene derived NHC–CuCl catalysts, the best results (up to 94% yield) were obtained with [(IiPr)CuCl]. The method has several key features, such as mild reaction conditions, tolerance of various

• )–H Arylation In 2014, Cazin and co-workers accomplished the C(sp2)–H arylation of acidic arenes by using a cooperative NHC–Cu/NHC–Pd catalytic system in the presence CsOH (Scheme 73) [95]. [(It-Bu)CuCl] changes in situ into the catalytically active species [(It-Bu)CuOH], which induces C(sp2)–H

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• elimination (e.g., with the β-dicarbonyl or arene) could occur (see Scheme 1). A prominent example of the coupling occurring between the Lewis base and the arene is in reactions with fluoride, which has been translated to enable the radiofluorination of non-activated arenes. While this fluorination reaction

• and electron-poor arenes 57, including hindered ortho-substituted derivatives (Scheme 12). Further derivatization of the spirocyclic motif led to SPIAd-derived iodonium ylides 58, whose radiofluorinations showed improved radiochemical conversions with a variety of arene derivatives (Scheme 13) [16

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• photon (400–700 nm; 1.8–3.1 eV). In addition, this energy is also diminished by as much as ≈25% through vibrational relaxation, internal conversion and intersystem crossing [11] and hence, many highly stabilized molecules including important feedstock molecules such as arenes, haloarenes or olefins

• limited to electron-poor arenes like diazonium/iodonium salts or aryl iodides with electron-withdrawing substituents as aryl radical precursors, due to the limited accessible reducing power of photocatalysts that relied on a monophotonic excitation event. However, the vast majority of inexpensive

The unique reactivity of 5,6-unsubstituted 1,4-dihydropyridine in the Huisgen 1,4-diploar cycloaddition and formal [2 + 2] cycloaddition

• Xiu-Yu Chen,
• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 982–990, doi:10.3762/bjoc.19.73

• ]. The well-known Huisgen 1,4-dipoles have a special kind of zwitterionic intermediates and are usually prepared by a nucleophilic addition of pyridine, quinoline, isoquinoline and other aza-arenes to electron-deficient alkynes [4][5][6][7][8]. The reactive Huisgen 1,4-dipoles have been widely employed

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• supramolecular systems derived from water-soluble macrocycles, including cyclodextrins (CDs), calix[n]arenes (CXs), cucurbiturils (CBs), and pillararenes have been widely studied [2][6][7][8]. Similar to those macrocyclic acceptors, tribenzotriquinacene (TBTQ) derivatives, a class of versatile host molecules

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• proceeds similarly to Nakamura’s Fe-catalyzed methodology (Scheme 13) [48]. In 2017, the Cheng laboratory investigated the Co-catalyzed ring-opening/dehydration of oxabicyclic alkenes via the C–H activation of arenes (Scheme 15) [50]. First, the group explored the ortho-naphthylation of N-pyrimidinylindole

• -catalyzed [3 + 2] annulation/ring-opening/dehydration domino reaction of oxabicyclic alkenes 30 with 2-(1-methylhydrazinyl)pyridine (MHP) directed arenes 87 for the synthesis of benzo[b]fluorenones 88 (Scheme 16) [52]. C–H bond functionalization with heterobicyclic alkenes as annulation partners has

Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• year, the group of Huang reported an elegant and straightforward palladium(II)-catalyzed ortho-selective trifluoromethylthiolation of arenes bearing various directing groups using the nucleophilic trifluoromethylthiolating source AgSCF3 in combination with Selectfluor® as oxidant (Scheme 6, 29 examples

• groups as well as halogens (16b–f, 62–91% yields). The meta-substituted (16f) and disubstituted (16j) products were obtained in high yields (73% and 79%, respectively). In 2018, Anbarasan and co-workers described a palladium-catalyzed trifluoromethylthiolation of arenes by C–H bond activation bearing

• moderate yields. Finally, the SeCF3-containing β-methylacrylamide 40n was also obtained in 37% yield. II. Transition-metal-catalyzed fluoroalkoxylation of (hetero)arenes by C–H bond activation II.1) Fluoroalkoxylation of aromatic C(sp2)–H bonds by transition-metal catalysis Over the last years, key

Practical synthesis of isocoumarins via Rh(III)-catalyzed C–H activation/annulation cascade

• Qian-Ci Gao,
• Yi-Fei Li,
• Jun Xuan and
• Xiao-Qiang Hu

Beilstein J. Org. Chem. 2023, 19, 100–106, doi:10.3762/bjoc.19.10

• of 1,2-difunctionalized arenes with alkynes or carbon monoxide (Scheme 1b, III) [13][14][15][16], have been widely applied for the assembly of isocoumarins over the past decades. Recently, the transition-metal-catalyzed ortho C–H activation/annulation of benzoic acids has emerged as an attractive

Two-step continuous-flow synthesis of 6-membered cyclic iodonium salts via anodic oxidation

• Julian Spils,
• Thomas Wirth and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 27–32, doi:10.3762/bjoc.19.2

• nucleophilic arenes under oxidative acidic conditions.The synthesis of CDIS is more challenging since the arene moiety must be covalently connected to the iodoarene prior to cyclization. Recently, we published two new methods that describe the generation of carbon- and heteroatom-bridged CDIS [28][29]. Herein

• isolated in 34% yield indicating that steric effects play a role during the oxidation step. We further wanted to investigate different arenes, but due to the lack of selectivity of the primary benzyl acetates in the Friedel–Crafts step, we were limited to para-substituted arenes, which unfortunately all

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• . Tetracene has limited solubility in several organic solvents such as chloroform, DMSO, THF, and chlorinated arenes [34][35][36]. Its solubility sufficiently increases with temperature, even more in a sealed vial where low boiling point solvents can be heated more. This way, we obtained concentrated hot

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

• cyclopropanes with arenes [29]. They have also been used in Pd-catalyzed cross-coupling reactions to react with hypervalent iodonium salts, organostananes, and vinyl epoxides [30][31][32]. Moreover, there are reports of them serving as oxidizing agents for alcohols [33]. Two papers have recently reported

B–N/B–H Transborylation: borane-catalysed nitrile hydroboration

• Filip Meger,
• Alexander C. W. Kwok,
• Franziska Gilch,
• Dominic R. Willcox,
• Alex J. Hendy,
• Kieran Nicholson,
• Andrew D. Bage,
• Thomas Langer,
• Thomas A. Hunt and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2022, 18, 1332–1337, doi:10.3762/bjoc.18.138

• , 93%, 1l, 74%) positions. An increased temperature of 80 °C was required for the efficient hydroboration for ortho-substituted aryl nitriles (1f, 1g, 1h), due to increased steric encumbrance close to the nitrile bond. The chloro-, bromo-, and iodo-substituted arenes provide a functional handle for

Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives

• Oleg A. Levitskiy,
• Olga I. Aglamazova,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2022, 18, 1166–1176, doi:10.3762/bjoc.18.121

• recently, two publications from the Werz group appeared concerning anodic activation of donor–acceptor cyclopropanes followed by their functionalization with arenes [43] or yielding oxy-ketones or 1,2-dioxanes [44]; the latter process was inspired by a previous report of Buriez [45]. The anodic

Facile and diastereoselective arylation of the privileged 1,4-dihydroisoquinolin-3(2H)-one scaffold

• Dmitry Dar’in,
• Grigory Kantin,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1070–1078, doi:10.3762/bjoc.18.109

• optimum conditions for the C-arylation of diazo substrates 10 (60 equiv ArH, 1.5 equiv TfOH, DCM, rt, 15 min), we proceeded to investigate the scope of this transformation for 4-diazo-3(2H)-isoquinolones 10a–s as well as various arenes (Scheme 3). In all cases, this (generally high-yielding

• , less electron-rich arenes furnished higher amounts of the 3-isoquinolone 15 byproduct compared to their electron-rich counterparts (cf. 9o vs 9p). Likewise, electron-donating substituents in the 4-diazo-3(2H)-isoquinolone benzene ring increased the tendency of 3-isoquinolones 15 to form (cf. 9(15)f–h

• ). Using more reactive (electron-rich) arenes results in lower diastereoselectivity and regiospecificity of the reaction (cf. 9q, 9v, and 9w). The structure and the initially anticipated trans-configuration of the products 9 was unequivocally confirmed by 1H and 13C NMR spectroscopy as well as, in the case

Electrochemical Friedel–Crafts-type amidomethylation of arenes by a novel electrochemical oxidation system using a quasi-divided cell and trialkylammonium tetrafluoroborate

• Hisanori Senboku,
• Mizuki Hayama and
• Hidetoshi Matsuno

Beilstein J. Org. Chem. 2022, 18, 1040–1046, doi:10.3762/bjoc.18.105

• 1,3,5-trimethoxybenzene or indoles in DMA containing 0.1 M iPr2NHEtBF4 using an undivided cell equipped with a Pt plate cathode and a Pt wire anode (a quasi-divided cell) resulted in selective formation of N-acyliminium ions of DMA at the anode, which reacted with arenes to give the corresponding

• synthesis [1][2][3][4]. For example, Friedel–Crafts-type amidomethylation [5][6][7][8][9][10][11][12][13][14][15] proceeds efficiently by the reaction of N-acyliminium ions with electron-rich arenes to give the corresponding amidomethylated products in good yields. Since amides are important intermediates

• has also been applied to organic synthesis [17][18][19][20]. However, when electrochemical oxidation of amides/carbamates in the presence of nucleophiles, such as electron-rich arenes or silyl enol ethers, is carried out for Friedel–Crafts-type amidomethylation, electrochemical oxidation of electron

Copper-catalyzed multicomponent reactions for the efficient synthesis of diverse spirotetrahydrocarbazoles

• Shao-Cong Zhan,
• Ren-Jie Fang,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 796–808, doi:10.3762/bjoc.18.80

• include Me (6a), OMe (6b, 6c), NMe2 (6d), NO2 (6e), and Cl (6f, 6g), could be well tolerated in this reaction. Importantly, the reaction is not sensitive to the electronic properties of the arenes, as the substrates bearing either electron-donating (6a–d), or electron-withdrawing (6e–g) groups on the aryl