Isolation and characterization of new phenolic siderophores with antimicrobial properties from Pseudomonas sp. UIAU-6B

• Emmanuel T. Oluwabusola,
• Olusoji O. Adebisi,
• Fernando Reyes,
• Kojo S. Acquah,
• Mercedes De La Cruz,
• Larry L. Mweetwa,
• Joy E. Rajakulendran,
• Digby F. Warner,
• Deng Hai,
• Rainer Ebel and
• Marcel Jaspars

Beilstein J. Org. Chem. 2021, 17, 2390–2398, doi:10.3762/bjoc.17.156

• ), δC 170.0.0 (C-7), and δC 169.4 (C-10). The downfield methine proton signals at δH 6.96 (d, J = 8.7, 1.8 Hz, H-2), 7.52 (td, J = 8.7, 7.2, 1.8 Hz, H-3), 6.94 (td, J = 8.7, 1.8 Hz, H-4), and δH 7.99 (dd, J = 8.1, 1.8 Hz, H-5) were consistent with a 1,2-disubstituted aromatic benzene ring of a salicylic

Synthesis of phenanthridines via a novel photochemically-mediated cyclization and application to the synthesis of triphaeridine

• Songeziwe Ntsimango,
• Kennedy J. Ngwira,
• Moira L. Bode and
• Charles B. de Koning

Beilstein J. Org. Chem. 2021, 17, 2340–2347, doi:10.3762/bjoc.17.152

• proceeding by means of the initial generation of an iminyl radical that cyclizes onto the electron-rich aromatic ring or through the formation of a radical cation on the electron-rich benzene ring. Finally, the methodology has successfully been applied to synthesizing the natural product trisphaeridine

Phenolic constituents from twigs of Aleurites fordii and their biological activities

• Kyoung Jin Park,
• Won Se Suh,
• Da Hye Yoon,
• Chung Sub Kim,
• Sun Yeou Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2021, 17, 2329–2339, doi:10.3762/bjoc.17.151

• (Table 1) of compound 1 displayed characteristic resonances for a 1,3,4-trisubstituted benzene ring [δH 7.00 (d, J = 1.9 Hz, H-2), 6.87 (dd, J = 8.1, 1.9 Hz, H-6), and 6.78 (d, J = 8.1 Hz, H-5)], a 1,3,4,5-tetrasubsituted benzene ring [δH 6.62 (brs, H-2′) and 6.65 (brs, H-6′)], an oxygenated methine [δH

• (Table 1) showed a 1,3,4-trisubstituted benzene ring [δH 6.58 (d, J = 2.3 Hz, H-2), 6.57 (d, J = 8.0 Hz, H-5), and 6.49 (dd, J = 8.0, 2.3 Hz, H-6); δC 146.9 (C-3), 143.9 (C-4), 131.9 (C-1), 121.2 (C-6), 114.2 (C-5), and 112.2 (C-2)], a 1,3,4,5-tetrasubstituted benzene ring [δH 6.73 (s, H-2′, 6′); δC

A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids

• Li Liu,
• Yue Li,
• Tiao Huang,
• Dulin Kong and
• Mingshu Wu

Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150

• -withdrawing motifs, and thus gave a better result. For example, the (2-oxoindolin-3-yl) phosphate substrates with a methyl or methoxy group at the 5-position of the benzene ring could all react with hydrobromic acid in good yield, giving 4b, 4c, and 4g in 72–76% yield. The position of the residue R1 on the

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• substituted diaryl ketone, 4-(4-methoxybenzoyl)benzonitrile (96) serves as the HAT photocatalyst to activate the C(sp3)–H bonds for olefin functionalization. It was identified that the use of nonpolar, aprotic solvents, such as benzene and α,α,α-trifluorotoluene (TFT) is critical for the formation of the

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• benzene which resulted in low yields of the products 134 (Scheme 18a) [44]. Using different N-protected substituted indoles 135, Naidu observed improved yields of 136 when catalytic oxidant I2 was added in 1,4-dioxane as solvent (Scheme 18b) [96]. Using aerial oxygen as the oxidant, Yang used Se0 in the

Enantioenriched α-substituted glutamates/pyroglutamates via enantioselective cyclopropenimine-catalyzed Michael addition of amino ester imines

• Zara M. Seibel,
• Jeffrey S. Bandar and
• Tristan H. Lambert

Beilstein J. Org. Chem. 2021, 17, 2077–2084, doi:10.3762/bjoc.17.134

• active (Table 1, entry 6). With the identification of cyclopropenimine 5 as our optimal catalyst [44], we examined the effect of the reaction medium. Solvents such as benzene (Table 1, entry 7), TBME (Table 1, entry 8), and toluene (Table 1, entry 10) produced reactivities on par with ethyl acetate and

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• three linearly fused benzene rings. Because of their extended aromatic and conjugated π-system, anthracene derivatives possess interesting photochemical and photophysical properties [1][2][3], as well as gelling ability [4]. These important properties make them relevant for the development and

• sequential modifications [30], photocyclization of divinylterphenyl derivatives [31], tandem radical cyclization of (Z,Z)-1,4-bis(2-iodostyryl)benzene derivatives [32], and ring-closing olefin metathesis of tetravinylterphenyls [33] as the best-known synthetic routes. Herein, we have classified the synthetic

• with internal alkynes 11 bearing an electron-donating or electron-withdrawing group on the benzene ring resulted in the corresponding substituted anthracenes 12 in moderate to good yields (see the representative examples 12a–g). The same authors also investigated the applicability of reacting internal

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• biologically active molecules (22 and 23) (Scheme 9A) [92]. Interestingly, the same conditions could be used for benzene hydroxylation to obtain phenol but were ineffective with benzene rings bearing either electron-donating or electron-withdrawing substituents. Notably, the catalyst could be reused five times

• reaction suggested it goes through a radical pathway. Similar to the oxidation of alkanes to give alcohols and carbonyl compounds, vanadium complexes have been reported to mediate the hydroxylation of arenes, including the obtaining of phenol from benzene. However, most mechanistic studies provided

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• room temperature within 0.1 h for a successful reaction. The salt 5-4v was so powerful that it fluorinated an equimolar amount of benzene in dichloromethane in 2 h at 40 °C. In general, triflate salts were more effective than BF4 salts because of the higher solubility of the triflate salts in a

• reactivity than the sulfonamide reagents such as Barnette’s N-fluoro-N-alkylarenesulfonamides, since the electronic density on the nitrogen was greatly decreased by two strong electron-withdrawing CF3SO2 groups. Reagent 7-1a reacted slowly with benzene and toluene under neat conditions, whereas activated

• fluorination of benzene and anisole under excess substrate conditions gave fluorobenzene and fluoroanisoles in 88% and 98% yield, respectively. The reaction with sodium diethyl phenylmalonate gave the fluorinated product in 93% yield (Scheme 26). 1-12. N-Fluorolactams A new class of N-F fluorinating agents, N

Breaking paracyclophane: the unexpected formation of non-symmetric disubstituted nitro[2.2]metaparacyclophanes

• Suraj Patel,
• Tyson N. Dais,
• Paul G. Plieger and
• Gareth J. Rowlands

Beilstein J. Org. Chem. 2021, 17, 1518–1526, doi:10.3762/bjoc.17.109

• ]metaparacyclophane and a cyclohexadienone cyclophane. Keywords: cyclophane; metaparacyclophane; nitration; paracyclophane; rearrangement; Introduction Cyclophanes have been described as having bent and battered benzene rings [1] due to a structure that involves one, or more, aromatic rings linked by aliphatic

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

• Jie Zheng,
• Shuyu Meng and
• Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

• , the reactions with other 2-(2-vinylphenyl)ethanals 13b–g carrying different substituents on the benzene ring or on the side chain with veratrole and furan as the nucleophiles were investigated. As can be seen from Scheme 7, under comparable conditions, most reactions proceeded smoothly with the

• in 38–72% yield. To our gladness, aldehyde 13d, with an electron-deficient nitro group residing on the benzene ring reacted with veratrole under the standard conditions, delivering tetralin 14da in 55% yield. However, using furan as the nucleophile component, the reaction sequence with 13d failed to

• )acetaldehydes or 3-(2-vinylphenyl)propanal by action with BF3 to generate benzyl carbenium ions that are captured by a Friedel–Crafts alkylation reaction with a range of electron-rich benzenes or heteroaromatics. The method has a relatively broad applicability allowing variation in the benzene ring as well as

Co-crystallization of an organic solid and a tetraaryladamantane at room temperature

• Fabian Rami,
• Jan Nowak,
• Felix Krupp,
• Wolfgang Frey and
• Clemens Richert

Beilstein J. Org. Chem. 2021, 17, 1476–1480, doi:10.3762/bjoc.17.103

• by crystallization at room temperature, using dichloromethane as solvent. Results We opted for a benzene derivative for our first foray into organic solids to be encapsulated in TAA crystals, because a number of benzene derivatives have been found in EnOCs in the past [13][14][15]. Phenol was

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

• anhydro nucleoside 26 and its transformation into the aminonucleoside 27. The key intermediate nucleoside 27 was then treated with 3-ethoxypropenoyl isocyanate or 3-methoxy-2-methylpropenoyl isocyanate in a mixture of benzene and DMF, followed by acidification with sulfuric acid affording the nucleosides

• and treatment with pyrrolidine in acetonitrile to afford the C-3’-aminonucleoside 58. The reaction of this key intermediate with 3-ethoxypropenoyl isocyanate or 3-methoxy-2-methylpropenoyl isocyanate in a solvent mixture of benzene and DMF, followed by acidification with sulfuric acid produced the

• solution mixture of benzene and DMF, followed by acidification with sulfuric acid produced nucleosides 63 and 64, respectively (Scheme 14) [47]. 1,4-Furanosyl double-headed nucleosides A literature search revealed two different categories of 1,4-furanosyl double-headed nucleosides. In the first category

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• be considered as a 1,3,5‐triphenylbenzene derivative enjoying with three methylene units clipped in such a manner that all the four benzene rings are in conjugation with coplanar arrangement, resulting strong π–π stacking in addition to the strong electron‐donating ability which in turns provide a

• corresponding desired truxene-based oxazole derivatives (Scheme 6). Additionally, to enhance the conjugation which in turn would undoubtedly tune the properties of the truxene-based heterocyclic systems, we also design and synthesized the benzene-bridged oxazole derivative 25 in three steps (Scheme 7). As can

• . 320.41 nm and 291.07 nm in addition to an extra band at 263.22 nm due to the fusion of three benzene rings onto the imidazole moieties. In sharp contrast, more red-shifted absorption bands at 341.64 nm and 326.99 nm along with two shoulders at ca. 306.75 nm, and 279.94 nm were found with truxene having

Heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile: synthesis of diverse nitrogenous heterocyclic compounds

• Guanglong Pan,
• Qian Yang,
• Wentao Wang,
• Yurong Tang and
• Yunfei Cai

Beilstein J. Org. Chem. 2021, 17, 1171–1180, doi:10.3762/bjoc.17.89

• groups (such as methyl or methoxy) and electron-withdrawing groups (chloro, bromo, or cyano) at the para-position of the aryl ring smoothly reacted with acetonitrile to afford the 5-substituted cyanomethylated indolines 3a–f in good yields (67–75%). When the benzene ring of the substrates was changed to

Nitroalkene reduction in deep eutectic solvents promoted by BH₃NH₃

• Chiara Faverio,
• Monica Fiorenza Boselli,
• Patricia Camarero Gonzalez,
• Alessandra Puglisi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2021, 17, 1041–1047, doi:10.3762/bjoc.17.83

• attention on the use of some choline chloride (ChCl)-based eutectic mixtures as reaction media. The reduction of β-nitrostyrene to afford (2-nitroethyl)benzene was selected as model reaction, and it was performed typically in the presence of 1 molar equiv of ammonia borane for 18 h at 60 °C (see Table 1

Highly regio- and stereoselective phosphinylphosphination of terminal alkynes with tetraphenyldiphosphine monoxide under radical conditions

• Dat Phuc Tran,
• Yuki Sato,
• Yuki Yamamoto,
• Shin-ichi Kawaguchi,
• Shintaro Kodama,
• Akihiro Nomoto and
• Akiya Ogawa

Beilstein J. Org. Chem. 2021, 17, 866–872, doi:10.3762/bjoc.17.72

• near-UV region. When benzene was used instead of CDCl3 under xenon lamp irradiation, the reaction did not proceed because 1 was less soluble in benzene than CDCl3 (Table 1, entry 4). The radical initiator, V-40, was found to be an appropriate initiator for the generation of phosphorus-centered radicals

• the phosphinylphosphination of alkynes Ph2P(O)PPh2 (1, 0.6 mmol) and an alkyne (2, 0.4 mmol) were placed in a Schlenk tube with CDCl3 or benzene (super dehydrated) under argon atmosphere. V-40 was added to the mixture, and then the reaction was heated at 80 °C and stirred for 22 h. After the reaction

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• dehydration forms D and finally 12. The synthesized naphthoacridines 12 with 2,3-diaminonaphthalene produces 14 via dehydration and dehydrogenation. 2 Azepines Azepines are represented by unsaturated seven atom heterocyles with nitrogen replacing a carbon atom. The benzene-fused azepines known as

• ]diazepines 26 using substituted 2-formylbenzoic acids 25, phenylenediamine and tetronic acid with water as solvent (Scheme 8). The mechanism leading to the formation of the final product 24 and 26 involves an initial condensation between tetronic acid and benzene-1,2-diamine to give enaminone A. An

• the high nucleophilicity of the amino group in the substrate 23 to control the regioselectivity of the reaction (Scheme 9). 3 Indoles Indoles have a bicyclic structure consisting of a six-membered benzene ring fused with a five-membered nitrogen-containing pyrrole ring. Figure 3 depicts some of the

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• electrons from the electron-rich tertiary amine nitrogen atom to the electron-deficient benzene ring, achieving intramolecular electron transfer. Selective C–H-functionalization also includes no catalysts, oxidants, additives, acids and bases, which is of great significance in the synthesis and application

• derivatives, including electron-donating or electron-withdrawing substituent groups in the para- or meta positions at the benzene rings, giving corresponding products in moderate yield. This protocol is also suitable for the structural diversity of epoxides, providing a new activation approach for C(sp3)–H

• 60 and Umemoto reagent 20 as substrates as well as N-methylmorpholine (NMM) as organic base additive at room temperature (Scheme 21). The highly functionalized indole, pyrrole, benzofuran, and electron-rich benzene containing CF3 can be given in good yield. Given the redox potential of NMM and

Total synthesis of pyrrolo[2,3-c]quinoline alkaloid: trigonoine B

• Takashi Nishiyama,
• Erina Hamada,
• Daishi Ishii,
• Yuuto Kihara,
• Nanase Choshi,
• Natsumi Nakanishi,
• Mari Murakami,
• Kimiko Taninaka,
• Noriyuki Hatae and
• Tominari Choshi

Beilstein J. Org. Chem. 2021, 17, 730–736, doi:10.3762/bjoc.17.62

• ]quinoline framework via electrocyclization of 2-(pyrrol-3-yl)benzene containing a carbodiimide moiety as a 2-azahexatriene system. The employed six-step sequence afforded trigonoine B (1) in 9.2% overall yield. The described route could be employed for the preparation of various N-substituted 4

• by electrocyclization of 2-(pyrrol-3-yl)benzene containing a carbodiimide moiety as a 2-azahexatriene system. Results and Discussion Scheme 2 illustrates the retrosynthetic strategy designed to synthesize triogonoine B (1). It was speculated that the dihydroquinoline moiety of trigonoine B (1) could

• , trigonoine B (1), was achieved for the first time through the electrocyclization of 2-(pyrrol-3-yl)benzene bearing a carbodiimide moiety as a 2-azahexatriene system. The employed six-step sequence afforded the desired product 1 in 9.2% overall yield. Notably, the developed synthetic route could be used for

Synthesis of dibenzosuberenone-based novel polycyclic π-conjugated dihydropyridazines, pyridazines and pyrroles

• Ramazan Koçak and
• Arif Daştan

Beilstein J. Org. Chem. 2021, 17, 719–729, doi:10.3762/bjoc.17.61

• , dihydropyridazines 3a–f were oxidized to pyridazines. In contrast to dihydropyridazineamide 3e, the reaction of dihydropyridazines 3a–d and 3f with PIFA ([bis(trifluoroacetoxy)iodo]benzene) afforded the corresponding pyridazine derivatives 4a–d and 4f in good yields (79–95%). As a result of the reaction of PIFA with

Effective microwave-assisted approach to 1,2,3-triazolobenzodiazepinones via tandem Ugi reaction/catalyst-free intramolecular azide–alkyne cycloaddition

• Maryna O. Mazur,
• Oleksii S. Zhelavskyi,
• Eugene M. Zviagin,
• Svitlana V. Shishkina,
• Vladimir I. Musatov,
• Maksim A. Kolosov,
• Elena H. Shvets,
• Anna Yu. Andryushchenko and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2021, 17, 678–687, doi:10.3762/bjoc.17.57

• includes a [3 + 2] click reaction between the azide ion with the triple bond and further C–N coupling instead of the IAAC reaction. Compounds having no fused benzene ring or with a heterocyclic moiety instead could also be obtained via the tandem approach Ugi reaction/IAAC [15][16]. Despite the

• of our study, the Ugi products 6 were involved in IAAC. Compounds such as 6aab, 6abb and 6aeb with terminal alkyne fragment can be easily cyclized under thermal uncatalyzed conditions in various solvents – from nonpolar benzene to polar protic solvents, and even in water, depending on substrate

• solubility [20]. Firstly, we used a procedure similar to described by I. Akritopoulou-Zanze et al. [13] for cyclization: compound 6aab was refluxed in benzene for 8 hours until TLC monitoring demonstrated the full transformation of starting material into a new compound. The evaporation of the solution gave a

Synthesis, structural characterization, and optical properties of benzo[f]naphtho[2,3-b]phosphoindoles

• Mio Matsumura,
• Takahiro Teramoto,
• Masato Kawakubo,
• Masatoshi Kawahata,
• Yuki Murata,
• Kentaro Yamaguchi,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2021, 17, 671–677, doi:10.3762/bjoc.17.56

• isomers, in which the position of the fused benzene rings is different; of these, three are shown in Figure 1. The synthesis, crystal structure, and dynamic behavior of benzo[e]naphtho[2,1-b]phosphindole (A) with the C2 symmetry axis on the binaphthyl skeleton have been reported [9][10][11]. Synthetic

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• Polystyrene (PS): PS is a low-cost, hard and brittle plastic used both as a solid or foam in protective packaging, containers and trays [151]. It is a nonbiodegradable material accounting for about 10% of municipal solid waste [135]. It is soluble in benzene, carbon disulfide, chlorinated hydrocarbons, lower

• chirality of lactic acid, three forms of PLA (ʟ, PLLA; ᴅ, PDLA; ᴅʟ, PDLLA) with slightly different properties (crystallinity, Tg 60–65 °C, Tm 130–180 °C) exist [256]. PLA is soluble in benzene, tetrahydrofuran, ethyl acetate, propylene carbonate and dioxane [257], and it is biodegradable [258][259]. Because