Functionalization of 4-bromobenzo[c][2,7]naphthyridine via regioselective direct ring metalation. A novel approach to analogues of pyridoacridine alkaloids

• Benedikt C. Melzer,
• Alois Plodek and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2304–2310, doi:10.3762/bjoc.15.222

• the iodine quenching product 13), as D2O quenching of metalated arenes obtained with amide bases do not necessarily give complete deuteration. A hydrogen-bonded complex between the metalated species and TMP is postulated to undergo partial H/D exchange reactions with D2O before quenching takes place

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• stoichiometric amounts and/or toxic reagents [14]. Also, low functional group tolerance, being limited to activated arenes, the production of metal salts as stoichiometric byproducts, and poor levels of regioselectivity would always be observed, limiting the progress of fluorine chemistry to some extent. In this

• , promoting the C–F over C–O bond formation via an inner-sphere pathway. Fluorination of arenes, aryl bromides, -alcohols, -triflates, and -boronic acid derivatives: In 2013, Larhed and co-workers [51] established a one-pot, two-step fluorination of aryl alcohols via aryl nonafluorobutylsulfonates. This

• formed from A with Selectfluor or NFSI instead of an organometallic intermediate as usual. Then, the activated Pd(IV)–F electrophile B would be capable of electrophilic fluorination of weakly nucleophilic arenes. This unusual mechanism of catalysis may provide a new idea to the catalysis of C–H

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• strategy involved using a mesoionic carbene to direct C–H activation, but proved to form an unexpectedly unstable intermediate that was identified through high-resolution mass spectrometry. On route to our target, a new optimized method to mononitrocalix[4]arenes was developed, including optimized and high

• yielding transformations to azide and 1,2,3-triazole derivatives which may have application in other areas of research. Keywords: calixarene; inherent chirality; mesoionic carbene; mononitration; ruthenacycle; Introduction Calix[4]arenes are a class of diverse macrocyclic compounds which have been the

• subject of extensive study since the mid-twentieth century [1]. Obtained from the base-catalyzed condensation of para-alkylated phenols and formaldehyde, calix[4]arenes have cyclic bowl-like structures which provide various sites for controlled chemical modifications. The versatility of calix[4]arenes has

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• [1][2][11][12]. Moreover, the designed macrocycles are useful molecular tools in the investigation of supramolecular catalysis and reaction mechanisms [1][2][13][14][15][16]. Heteracalixaromatics or heteroatom-bridged calix(het)arenes [17][18][19][20][21] are synthetic macrocycles composed of

• heteroatoms and meta-(het)arenes in an alternative manner. Because of the interplay between heteroatoms and aromatic rings, heteracalixaromatics possess versatile molecular recognition properties and have found wide supramolecular applications. Very recently, we have devised coronarenes [22] simply through

• operational one-pot reaction fashion on the basis of a nucleophilic aromatic substitution reaction [23][24][25][26][27][28][29][30][31]. To prepare functionalized corona[6]arenes using diethyl terephthalate as a starting material, we observed, however, the formation of a mixture of macrocyclic isomers because

Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkyl-substituted benzimidazoles with arenes in the superacid CF₃SO₃H. NMR and DFT studies of dicationic electrophilic species

• Dmitry S. Ryabukhin,
• Alexey N. Turdakov,
• Natalia S. Soldatova,
• Mikhail O. Kompanets,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1962–1973, doi:10.3762/bjoc.15.191

• nab., 7/9, Saint Petersburg, 199034, Russian Federation 10.3762/bjoc.15.191 Abstract Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkylbenzimidazoles with arenes in the Brønsted superacid TfOH resulted in the formation of the corresponding Friedel–Crafts reaction products, 2-diarylmethyl and 2

• reaction [14]. Recently, several hydroxyalkylation reactions followed by alkylation of arenes have been reported involving heterocycle-based superelectrophiles: pyridines, thiazoles, quinolines, isoquinolines, pyrazines, pyrazoles, imidazole and furans, bearing a formyl (carbonyl) group [15][16][17][18][19

• (Figure 3) with arenes under the action of Brønsted (super)acids CF3SO3H (TfOH, triflic acid), H2SO4 and strong Lewis acids AlX3 (X = Cl, Br). One would expect the electrophilic activation of carbonyl or 2-hydroxyalkyl groups of these benzimidazoles in hydroxyalkylation and alkylation of arenes. Results

Complexation of chiral amines by resorcin[4]arene sulfonic acids in polar media – circular dichroism and diffusion studies of chirality transfer and solvent dependence

• Bartosz Setner and
• Agnieszka Szumna

Beilstein J. Org. Chem. 2019, 15, 1913–1924, doi:10.3762/bjoc.15.187

• ]arenes with sodium sulfite and formaldehyde according to a general synthetic procedure [15]. While the synthetic procedure for water soluble RSAs is straightforward, purification of the final products is tricky and highly substrate-dependent. RSA 1 was obtained in 92% yield after purification involving

• Information File 1). Tetrakis((α)–methylbenzylaminomethyl)resorcin[4]arenes ((R)-2 and (S)-2) were obtained according to the literature procedures [16]. To a solution of C-(3-hydroxypropyl)resorcin[4]arene (720 mg, 1 mmol) and excess formaldehyde (40% in water, 1 mL) in methanol (30 mL), (R)-(+)-1

• Information File 1). Capsule formation: Capsules formed between tetrakis(sulfonatomethyl)resorcin[4]arene 1 (11 mg, 0.01 mmol) and tetrakis((α)-methylbenzylaminomethyl)resorcin[4]arenes (R)-2 or (S)-2 (14 mg, 0.01 mmol) were prepared by dissolving in water (1 mL) and mixing two resorcin[4]arene derivative

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• base-free, unsolvated complex that preferably had been crystallographically characterized limited the choice to the potassium complex [KA']∞. In that form [17], as well as when crystallized from THF [18], DME [21], or as described below, arenes, [KA']∞ retains the structure of an undulating or helical

Complexation of 2,6-helic[6]arene and its derivatives with 1,1′-dimethyl-4,4′-bipyridinium salts and protonated 4,4'-bipyridinium salts: an acid–base controllable complexation

• Jing Li,
• Qiang Shi,
• Ying Han and
• Chuan-Feng Chen

Beilstein J. Org. Chem. 2019, 15, 1795–1804, doi:10.3762/bjoc.15.173

• are also the epitome of complex-binding pockets of enzymes [3]. Macrocyclic arenes including calixarenes [4][5], resorcinarenes [6], cyclotriveratrylenes [7][8], pillararenes [9], biphen[n]arenes [10] and others [11][12] are all composed of hydroxy-substituted aromatic rings bridged by methylene or

• macrocyclic arenes with diverse functional groups are also important for the development of various new host–guest supramolecular systems [23][24][25][26][27][28][29]. Helic[6]arenes [30], a new kind of macrocyclic arenes, are composed of 2,6-dihydroxy-substituted triptycene subunits bridged by methylene

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Synthesis, enantioseparation and photophysical properties of planar-chiral pillar[5]arene derivatives bearing fluorophore fragments

• Guojuan Li,
• Chunying Fan,
• Guo Cheng,
• Wanhua Wu and
• Cheng Yang

Beilstein J. Org. Chem. 2019, 15, 1601–1611, doi:10.3762/bjoc.15.164

• : aggregation; circular dichroism; chirality; click chemistry; macrocycles; pillar[5]arenes; Introduction Planar-chiral compounds are structurally appealing and potentially applicable in various functional materials such as chiral discriminators [1][2], chiral polymers, supramolecular sensors [3] and chiral

• versatile functionality [9] in recent years. Pillar[5]arenes [10], are cyclic pentamers composed of 1,4-dialkoxybenzene units connected through methylene bridges at the para-position and have a unique symmetrical architecture with an overall cylindrical or pillar-like shape. By virtue of their rigid and

• symmetrical structures, as well as highly tunable functionality, the studies on pillar[5]arenes have been developed rapidly in various areas, such as artificial transmembrane channels [11][12], molecular complexation [13][14] and nonporous adaptive crystals [15][16][17]. One of the features of pillar[5]arenes

Superelectrophilic carbocations: preparation and reactions of a substrate with six ionizable groups

• Sean H. Kennedy,
• Makafui Gasonoo and
• Douglas A. Klumpp

Beilstein J. Org. Chem. 2019, 15, 1515–1520, doi:10.3762/bjoc.15.153

• sufficiently acidic media, cationic electrophiles such as the nitronium ion may undergo protonation, leading to the nitronium dication (1), and a greatly enhanced electrophilic reactivity. In superacidic solutions, nitronium salts have been shown to react with deactivated arenes and saturated hydrocarbons

Different reactivity of phosphorylallenes under the action of Brønsted or Lewis acids: a crucial role of involvement of the P=O group in intra- or intermolecular interactions at the formation of cationic intermediates

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1491–1504, doi:10.3762/bjoc.15.151

• such phosphorylallenes under the action of Brønsted or Lewis acids. Apart from that, the reaction of dichlorophosphorylallenes with arenes and AlCl3 led to products of hydroarylation of the allene system, phosphoryl-substituted alkenes and/or indanes. This is the first example of a Lewis acid-promoted

• ][16]. It should be especially emphasized that intermolecular reactions of phosphorylallenes with arenes have not been yet achieved. In general, intermolecular hydroarylation of allenes has been developed for reactions catalyzed by complexes of various metals [17], such as Pd [18][19][20], Pt [21], Au

• [22][23][24][25], Ir [26], Rh [27][28], and Co [29]. However, only electron-rich allenes, bearing electron-donating substituents, take part in the metal-catalyzed reactions. There are just a few examples of Brønsted acid catalyzed intermolecular hydroarylations of allenes by electron-rich arenes

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• complexation of p-sulfonatocalix[n]arenes (SCnAs, n = 4, 5, 6, 8) with ammonium-modified TPE derivatives reported previously by us [54][55]. We assume that the geometrical confinement of P-TPE within GC5A restricts rotational freedom and thus hampers disfavorable non-radiative decay pathways. The inflection

Host–guest interactions between p-sulfonatocalix[4]arene and p-sulfonatothiacalix[4]arene and group IA, IIA and f-block metal cations: a DFT/SMD study

• Valya K. Nikolova,
• Cristina V. Kirkova,
• Silvia E. Angelova and
• Todor M. Dudev

Beilstein J. Org. Chem. 2019, 15, 1321–1330, doi:10.3762/bjoc.15.131

• biological activity of the calix[n]arenes on various life forms from viruses to human beings have been reported [22]. The first water-soluble calix[n]arene derivative, p-tert-butylcalix[4]arenetetracarboxylic acid, was synthesized in 1984 [23]. The first paper on the calixarenes having sulfonate groups (and

• selectivities; they have demonstrated excellent complex ability towards inorganic cations, organic ammonium cations, pyridinium guests, neutral molecules (alcohols, ketones, nitriles), dye molecules, etc. [26]. p-Sulfonatocalix[n]arenes are complexing agents for structurally diverse biologically active

• molecules [27], including some amino acids [28] and proteins [29]. They are also biocompatible: compared to other types of macrocyclic molecules such as cyclodextrins and cucurbiturils (which are also water soluble), p-sulfonatocalix[n]arenes do not exhibit any toxicity, which makes them applicable in

N-doped carbon dots covalently functionalized with pillar[5]arenes for Fe³⁺ sensing

• Jia Gao,
• Ming-Xue Wu,
• Dihua Dai,
• Zhi Cai,
• Yue Wang,
• Wenhui Fang,
• Yan Wang and
• Ying-Wei Yang

Beilstein J. Org. Chem. 2019, 15, 1262–1267, doi:10.3762/bjoc.15.123

• macrocyclic compounds, especially new macrocyclic arenes, have become one of the research hotspots in supramolecular chemistry [11][12][13][14]. Among them pillarenes as a relatively new family of pillar-shaped members discovered a decade ago have played a key role due to their unique conformations

Remarkable effect of alkynyl substituents on the fluorescence properties of a BN-phenanthrene

• Alberto Abengózar,
• David Sucunza,
• Patricia García-García and
• Juan J. Vaquero

Beilstein J. Org. Chem. 2019, 15, 1257–1261, doi:10.3762/bjoc.15.122

• to provide alkynyl-substituted BN-phenanthrenes 1e and 1f in excellent yields (Scheme 3). These results confirm the value of palladium-catalyzed cross-coupling reactions of chloro-substituted BN-arenes as a useful tool for the preparation of derivatives functionalized with a range of substituents of

• -arenes with improved properties. Further studies into the effect of alkynyl substituents on the fluorescence of BN-arenes are currently ongoing in our laboratories. BN-phenanthrene 1a and synthesis of substituted derivatives proposed in this work. UV–vis absorption (top) and emission (bottom) spectra for

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• contributions aromatic aldehyde, imine or nitrile compounds have been used instead. For instance, 2-formylbenzonitriles 85 along with a variety of arenes 86 and diaryliodonium salts 87, combined in a copper-catalysed three-component cyclization produce 2,3-diarylisoindolinones 88 [103] (Scheme 25). The scope of

• was chemoselective, furnishing in good yields the products resulting from the transfer of the less hindered arene. However, this methodology exhibits two main limitations. First, arenes 86 with electron-withdrawing groups did not react under the optimized conditions and on the other hand, the atom

• dialkyl ones (Scheme 26, path A) [104]. When cyclopropyl ketones 91 were used as substrates, a ring expansion and a new quaternary centre formation happened through the multicomponent reaction to produce pentacyclic derivatives 92 (Scheme 26, path B) [105]. These reactions, either with arenes 86 or

Stereo- and regioselective hydroboration of 1-exo-methylene pyranoses: discovery of aryltriazolylmethyl C-galactopyranosides as selective galectin-1 inhibitors

• Alexander Dahlqvist,
• Axel Furevi,
• Niklas Warlin,
• Hakon Leffler and
• Ulf J. Nilsson

Beilstein J. Org. Chem. 2019, 15, 1046–1060, doi:10.3762/bjoc.15.102

• mesyl chloride in pyridine at 0 °C to give 2-deoxy-1-mesylgalactoheptulose 8 (91%), followed by a nucleophilic substitution reaction with sodium azide in dimethylformamide to give the azide 9 in good yield (90%) [26]. The azide 9 was reacted with a panel of substituted ethynyl arenes to give

• yields varying from poor to good (10–87% yields, Scheme 2). The transfer hydrogenation was selected as common hydrogenation using conditions with hydrogen gas and palladium on carbon lead to very low yields or no recovered product during the synthesis of 1a,b. Unfortunately, no arenes bearing halogen

Fabrication, characterization and adsorption properties of cucurbit[7]uril-functionalized polycaprolactone electrospun nanofibrous membranes

• Changzhong Chen,
• Fengbo Liu,
• Xiongzhi Zhang,
• Zhiyong Zhao and
• Simin Liu

Beilstein J. Org. Chem. 2019, 15, 992–999, doi:10.3762/bjoc.15.97

• engineering [6], energy storage [7], biosensors [8], catalysis [9], and environmental engineering [10]. Various supramolecular host molecules such as cyclodextrins (CDs), calix[n]arenes, and pillar[n]arenes can form host–guest inclusion complexes (ICs) with numerous compounds due to their unique cavity

• /nanoreactor and supramolecular polymers, etc. [25][27][28][29][30][31][32]. Unlike other hosts such as CDs, calix[n]arenes, or pillar[n]arenes, the fabrication of CB[n]-functionalized nanofibers by electrospinning is a challenging task due to the poor solubility of CB[n] in common solvents. To develop CB[n

A novel and efficient synthesis of phenanthrene derivatives via palladium/norbornadiene-catalyzed domino one-pot reaction

• Yue Zhong,
• Wen-Yu Wu,
• Shao-Peng Yu,
• Tian-Yuan Fan,
• Hai-Tao Yu,
• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2019, 15, 291–298, doi:10.3762/bjoc.15.26

• to multisubstituted arenes. In the previous work, we innovatively developed a strategy for the remote C–H alkylation of arenes [18]. Recently, our group also achieved aromatic ketones [19] and 2-alkynyl aromatic ketones [20] successfully through ortho-acylation and ipso-Suzuki coupling or

Metal-free C–H mercaptalization of benzothiazoles and benzoxazoles using 1,3-propanedithiol as thiol source

• Yan Xiao,
• Bing Jing,
• Xiaoxia Liu,
• Hongyu Xue and
• Yajun Liu

Beilstein J. Org. Chem. 2019, 15, 279–284, doi:10.3762/bjoc.15.24

• [22] and 1,2-ethanedithiol [23]. In the past decades, C–H functionalization has become an effective strategy for constructing different molecules directly from simple arenes and alkanes. C–H functionalization is an important method for C–S coupling reactions [24][25]. For example, transition metal

Synthesis of a tyrosinase inhibitor by consecutive ethenolysis and cross-metathesis of crude cashew nutshell liquid

• Jacqueline Pollini,
• Valentina Bragoni and
• Lukas J. Gooßen

Beilstein J. Org. Chem. 2018, 14, 2737–2744, doi:10.3762/bjoc.14.252

• based on cross-metathesis of CNSL with ethylene [33][34][35]. Each unsaturated double bond isomer has the first double bond located at the C-8 position, so that no matter how many other double-bonds are present, the unsaturated side chains of all arenes will be shortened to ω-nonenyl groups if ethylene

Gold-catalyzed post-Ugi alkyne hydroarylation for the synthesis of 2-quinolones

• Xiaochen Du,
• Jianjun Huang,
• Anton A. Nechaev,
• Ruwei Yao,
• Jing Gong,
• Erik V. Van der Eycken,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2018, 14, 2572–2579, doi:10.3762/bjoc.14.234

• –Crafts-type cyclizations involving attack of electron-rich arenes on the triple bonds, leading to the formation of a great number of fused [50][51][52][53] and spirocyclic structures [54][55][56][57][58][59]. In addition, Ugi adducts have already been successfully utilized for the diversity-oriented

Synthesis of aryl sulfides via radical–radical cross coupling of electron-rich arenes using visible light photoredox catalysis

• Amrita Das,
• Mitasree Maity,
• Simon Malcherek,
• Burkhard König and
• Julia Rehbein

Beilstein J. Org. Chem. 2018, 14, 2520–2528, doi:10.3762/bjoc.14.228

• Amrita Das Mitasree Maity Simon Malcherek Burkhard Konig Julia Rehbein Department of Chemistry and Pharmacy, Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany 10.3762/bjoc.14.228 Abstract Electron-rich arenes react with aryl and alkyl

• disulfides in the presence of catalytic amounts of [Ir(dF(CF3)ppy)2(dtbpy)]PF6 and (NH4)2S2O8 under blue light irradiation to yield arylthiols. The reaction proceeds at room temperature and avoids the use of prefunctionalized arenes. Experimental evidence suggests a radical–radical cross coupling mechanism

• . Keywords: arenes; oxidation; photocatalysis; thiolation; visible light; Introduction The generation of carbon–sulfur bonds is an important task in organic synthesis, because of their abundance in target structures, such as natural products and drugs [1][2][3]. They are found in organic semiconductors

Calixazulenes: azulene-based calixarene analogues – an overview and recent supramolecular complexation studies

• Paris E. Georghiou,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Hidetaka Nishimura,
• Jaehyun Lee,
• Atsushi Wakamiya and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2018, 14, 2488–2494, doi:10.3762/bjoc.14.225

• relatively facile and reproducible syntheses of the classical calix[n]arenes 1 in which n = 4, 6 or 8, with phenolic groups linked or bridged via methylene groups to form defined three-dimensional basket-like cavities with “upper” or “lower” rims, were developed by Gutsche and co-workers [4][5][6]. As a

• result of Gutsche’s synthetic methodologies many researchers have been able to employ these calix[n]arenes and modified derivatives thereof in a great variety of ingenious applications. These applications have included a myriad of synthetic modifications to both, or either, of their upper and lower rims

• . Since these three calix[4]azulenes 3–5 are all-hydrocarbon compounds they differ significantly from the better-studied calix[4]arenes, which usually have some heteroatoms such as oxygen, nitrogen or sulfur in their structures. As a consequence, compounds 3–5 have solubility limitations. Furthermore, the