Cross-linked cyclodextrin-based material for treatment of metals and organic substances present in industrial discharge waters

• Élise Euvrard,
• Nadia Morin-Crini,
• Coline Druart,
• Justine Bugnet,
• Bernard Martel,
• Cesare Cosentino,
• Virginie Moutarlier and
• Grégorio Crini

Beilstein J. Org. Chem. 2016, 12, 1826–1838, doi:10.3762/bjoc.12.172

• for the use of carboxylic acids and pyromellitic dianhydride, respectively, as agents to cross-linking CDs. Other cross-linking agents such as epichlorohydrin, ethylene glycol diglycidyl ether, glutaraldehyde, benzoquinone or isocyanates can be also used [1][12]. The main objective of the study was to

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• were examined, such as Pd(OAc)2, PdCl2Ln, Pd2(dba)3, in the absence of added acid, but none led to cross-coupling at room temperature. 1,4-Benzoquinone (BQ) was found to be an effective additive in promoting the reaction, while addition of stoichiometric metal salts (e.g., silver or copper salts) was

• yields, and the reaction still required the use of stoichiometric silver salts in addition to benzoquinone. To overcome these limitations, further optimization of the catalyst system was conducted (Figure 5). A combination of AgNO3 or AgOAc and BQ was critical to obtain good yields of the same products

• partners, however, 847% (TON = 8.5) and 467% (TON = 4.7) yields of the products were obtained, respectively, supporting a key role for BQ in regeneration of the active dicationic species (PdL4(BF4)2). Benzoquinone (BQ) has been well studied as an oxidant for Pd(0) to Pd(II) processes, generating

Indenopyrans – synthesis and photoluminescence properties

• Andreea Petronela Diac,
• Ana-Maria Ţepeş,
• Albert Soran,
• Ion Grosu,
• Anamaria Terec,
• Jean Roncali and
• Elena Bogdan

Beilstein J. Org. Chem. 2016, 12, 825–834, doi:10.3762/bjoc.12.81

• -benzoquinone (DDQ), led to indeno-α-pyrones 4–6 (Scheme 2), in not very satisfying yields. Investigations carried out for the dehydrogenation reaction of the isomeric mixture 2'a/3''a (Scheme 2) revealed the formation of the α-pyrone 6a (15% yield), which was the oxidation product of isomer 3''a. In the same

A selective and mild glycosylation method of natural phenolic alcohols

• Mária Mastihubová and
• Monika Poláková

Beilstein J. Org. Chem. 2016, 12, 524–530, doi:10.3762/bjoc.12.51

• performed in the presence of known mild catalysts such as Ag2O [33] (method A), the less frequently used ZnO–ZnCl2 system [34] (method B) and the combination of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) with iodine (DDQ–I2) [35] (method C). In addition ZnO–I2 (method D) was successfully applied as a

Synthesis and reactivity of aliphatic sulfur pentafluorides from substituted (pentafluorosulfanyl)benzenes

• Norbert Vida,
• Jiří Václavík and
• Petr Beier

Beilstein J. Org. Chem. 2016, 12, 110–116, doi:10.3762/bjoc.12.12

• mechanism for the formation of the aliphatic SF5 compounds was presented and their chemical reactivity was investigated. SF5-substituted para-benzoquinone was synthesized; its oxidation led to an improved yield of 2-(pentafluorosulfanyl)maleic acid. The reaction of SF5-substituted maleic anhydride and para

• -benzoquinone with cyclopentadiene afforded the Diels–Alder adducts. Decomposition of 3-(pentafluorosulfanyl)muconolactone in acidic, neutral and basic aqueous media was investigated and the decarboxylation of 2-(pentafluorosulfanyl)maleic acid provided 3-(pentafluorosulfanyl)acrylic acid. Keywords

• transformations: electrophilic aromatic hydroxylation to the intermediate 6, oxidation to ortho-benzoquinone 7, Baeyer–Villiger (BV) oxidation, hydrolysis to muconic acid derivative 8, and finally intramolecular conjugate addition affording 3. Under certain conditions, small amounts of intermediates 6 and 8 were

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• the nitrogen atom, steric effects cannot be neglected. Another example of RCM involving alkenes that possess 2-chloropyridines was reported to produce dihydroisoquinoline 57 from 2,6-dichloro-3,4-diallylpyridine (56) [60]. The addition of benzoquinone prevented the isomerization of the double bond and

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• , Russian Federation 10.3762/bjoc.11.236 Abstract A series of derivatives of 2-hetaryl-1,3-tropolone (β-tropolone) was prepared by the acid-catalyzed reaction of 2-methylbenzoxazoles, 2-methylbenzothiazoles and 2,3,3-trimethylindoline with 3,4,5,6-tetrachloro-1,2-benzoquinone. The molecular structures of

• put forward by Schenk et al. [21] who reported on the preparation of a derivative of 1,2-tropolone 1 through condensation of 3,4,5,6-tetrachloro-1,2-benzoquinone (o-chloranil) with acetone. In the subsequent study of this reaction, the structure of its product analyzed with the use of two-dimensional

• 3,4,5,6-tetrachloro-1,2-benzoquinone with methylene-active five-membered heterocyclic compounds: 2-methylbenzoxazoles, 2-methylbenzothiazoles and 2,3,3-trimethylindoline. We have previously reported the synthesis of 2-(benzoxazolyl)-1,3-tropolones, 2-(benzothiazolyl)-1,3-tropolone, 2-(benzoxazolyl)-5,6,7

Cross metathesis of unsaturated epoxides for the synthesis of polyfunctional building blocks

• Meriem K. Abderrezak,
• Kristýna Šichová,
• Nancy Dominguez-Boblett,
• Antoine Dupé,
• Zahia Kabouche,
• Christian Bruneau and
• Cédric Fischmeister

Beilstein J. Org. Chem. 2015, 11, 1876–1880, doi:10.3762/bjoc.11.201

• using benzoquinone [32] as an additive to decrease the extent of double-bond migration. As depicted in Table 1 (entries 1–4), 10 mol % of benzoquinone were necessary to ensure a limited amount (<10%) of side products resulting from double-bond migration. However, addition of benzoquinone resulted in

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• derived from cyclopentadiene (111) and 1,4-benzoquinone. The diol 132 was produced by reduction of 131 in an efficient manner. To this end, the bis-O-allylated compound 133 was prepared by an allylation sequence using allyl bromide (37) in the presence of NaH starting with the diol 132, whereas compound

• from 199 via Grignard addition followed by O-allylation. The double DA adduct 199 has been derived from cyclopentadiene and 1,4-benzoquinone. Next, compound 202 was exposed to catalyst 2 in the presence of ethylene (24) to generate the expected hexacyclic system 203 (70%) containing 10 stereogenic

• -allylation sequence. The starting cycloadduct 321 was obtained by the double DA reaction between 1,3-cyclohexadiene and 1,4-benzoquinone. Further, treatment of 323 with catalyst 2 in the presence of titanium isopropoxide furnished the expected RRM product 324 in 92% yield (Scheme 70). Bicyclo[2.2.2]octene

Design and synthesis of propellane derivatives and oxa-bowls via ring-rearrangement metathesis as a key step

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2015, 11, 1727–1731, doi:10.3762/bjoc.11.188

• from readily accessible starting materials such as p-benzoquinone, 1,4-naphthoquinone and 1,4-anthraquinone. Keywords: allylation; propellane derivatives; quinones; ring-rearrangement metathesis; Introduction The synthesis of complex target structures requires bond-disconnection analysis of the

• -quinones (p-benzoquinone, 1,4-naphthoquinone or 1,4-anthraquinone) with a freshly cracked cyclopentadiene. To realize the synthetic strategy (Figure 1) to various propellane derivatives [29][30][31] and oxa-bowls, we commenced with the preparation of a known DA adduct 3a [32]. Subsequent allylation of 3a

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• [2,3,4-kl]acridin-4-one scaffold which could be considered as the pharmacophore. The cytotoxicity of 69–76 changes depending on the substituents attached to the benzoquinone moiety (Figure 10). Furthermore, shermilamines C (28), D (77) and F (30) also represent one of the interesting anticancer alkaloids

A facile synthetic route to benzimidazolium salts bearing bulky aromatic N-substituents

• Gabriele Grieco,
• Olivier Blacque and
• Heinz Berke

Beilstein J. Org. Chem. 2015, 11, 1656–1666, doi:10.3762/bjoc.11.182

• much as possible. In addition to the 1,3-benzoimidazolium salts prepared by Chianese and co-workers, polycyclic diaminocarbenes were reported possessing mesityl substituents in the N1,N2-positions and in addition benzoquinone [39][40] or quinone [41] imidazole annulated systems or those with an

Tandem cross enyne metathesis (CEYM)–intramolecular Diels–Alder reaction (IMDAR). An easy entry to linear bicyclic scaffolds

• Javier Miró,
• María Sánchez-Roselló,
• Álvaro Sanz,
• Fernando Rabasa,
• Carlos del Pozo and
• Santos Fustero

Beilstein J. Org. Chem. 2015, 11, 1486–1493, doi:10.3762/bjoc.11.161

• -bonding catalysts for Diels–Alder reactions [28]. However, in our case no influence was observed when the reaction was performed in the presence of diaryl thioureas (Table 1, entry 13). Finally, the use of benzoquinone (BQ) as an additive, which has been reported to suppress the formation of byproducts in

Pd(OAc)₂-catalyzed dehydrogenative C–H activation: An expedient synthesis of uracil-annulated β-carbolinones

• Biplab Mondal,
• Somjit Hazra,
• Tarun K. Panda and
• Brindaban Roy

Beilstein J. Org. Chem. 2015, 11, 1360–1366, doi:10.3762/bjoc.11.146

• % yield of 5a with 52% conversion of starting material. Increasing the temperature to 90 °C (Table 1, entry 2) afforded 63% yield of 5a with 80% conversion of 4a. Then different oxidants [Cu(OTf)2, PhI(OAc)2, K2S2O8, (NH4)2S2O8, p-benzoquinone (BQ), oxone, AgOAc, molecular oxygen] were examined under

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

Design and synthesis of fused polycycles via Diels–Alder reaction and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha and
• Ongolu Ravikumar

Beilstein J. Org. Chem. 2015, 11, 1259–1264, doi:10.3762/bjoc.11.140

• studied. Results and Discussion Our strategy to polycycles involves a Diels–Alder reaction (DA) [23][24][25], a Grignard addition [26] and a RRM as key steps. To begin with, a double DA reaction of cyclopentadiene (1) with 1,4-benzoquinone (2) gave the known bis-adduct 3 [27][28]. Later, it was reacted

• this strategy, next we focussed on the preparation of an analogous bicyclo[2.2.2] system and to this end, the DA reaction of 1,3-cyclohexadiene (7) with 1,4-benzoquinone (2) furnished the known bis-adduct 8 [27][28], which on treatment with allylmagnesium bromide delivered diol 9. Later, O-allylation

• reaction and RRM as key steps. Here, we generated polycyclic compounds with 10 stereocenters involving six fused rings in four steps starting with readily available starting materials such as 1,3-cyclopentadiene, 1,3-cyclohexadiene and 1,4-benzoquinone. Further studies to expand the scope of this strategy

Advances in the synthesis of functionalised pyrrolotetrathiafulvalenes

• Luke J. O’Driscoll,
• Sissel S. Andersen,
• Marta V. Solano,
• Dan Bendixen,
• Morten Jensen,
• Troels Duedal,
• Jess Lycoops,
• Cornelia van der Pol,
• Rebecca E. Sørensen,
• Karina R. Larsen,
• Kenneth Myntman,
• Christian Henriksen,
• Stinne W. Hansen and
• Jan O. Jeppesen

Beilstein J. Org. Chem. 2015, 11, 1112–1122, doi:10.3762/bjoc.11.125

• -benzoquinone (DDQ) gives 6, which is purified by column chromatography, in 52% overall yield (22.5 g) from 12. We have also consistently obtained comparable yields of around 55% using the same method at approximately half this scale. The ability to isolate multigram quantities of 6, which can be stored for

Bis(vinylenedithio)tetrathiafulvalene analogues of BEDT-TTF

• Erdal Ertas,
• İlknur Demirtas and
• Turan Ozturk

Beilstein J. Org. Chem. 2015, 11, 403–415, doi:10.3762/bjoc.11.46

• of 52 was prepared with the acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) 53 (1:1) in dichloromethane at room temperature to investigate the optical constant and optical band gap of the complex (Scheme 8) [56]. A solution of the salt was evaporated on a quartz substrate until ≈110 nm

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• that the selectivity of the reaction can be controlled by changing the polarity of the solvent. The reactions of terminal alkens with the Pd(OAc)2/benzoquinone system in a mixture of DMSO and AcOH as the solvent selectively produced linear E-allyl acetates in 50–65% yield [218]. The reaction in acetic

• acid affords methyl ketone and vinyl acetate; branched allyl ether is formed as the major product in the CH2Cl2/AcOH system using the 1,2-bis (benzylsulfinyl)ethane ligand [218]. The acyloxylation of terminal alkenes 232 with carboxylic acids 233 in the presence of 1,4-benzoquinone (BQ) as the oxidant

• , vinyl phenyl sulfoxide ligand 234, and Pd(OAc)2 resulted in the selective formation of branched allyl esters 235 [217]. This reaction afforded linear esters 236 as byproducts. Apparently, ligand 234 serves for the formation of the π-allyl–palladium intermediate, and benzoquinone mediates the subsequent

Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

• Kuppusamy Bharathimohan,
• Thanasekaran Ponpandian,
• A. Jafar Ahamed and
• Nattamai Bhuvanesh

Beilstein J. Org. Chem. 2014, 10, 3031–3037, doi:10.3762/bjoc.10.321

• , Cu(OAc)2, benzoquinone and O2 among others. In the present study, we have chosen a Cu2+ salt because it can be used as an oxidant and as a pre-catalyst for the C–H functionalization and the decarboxylative CuAAC reaction, respectively. 1-(2-Azidophenyl)-1H-benzo[d]imidazole (1a) and phenylpropiolic

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• anodically generated 1,2-benzoquinone undergoes a Michael reaction with 62 under formation of adduct 63, which is further oxidized to give benzoquinone 64. Finally, anellation proceeds in a second Michael addition step under formation of heterocyclic compound 65. In the reported cases, both the generation of

• 1,2-benzoquinone and the anellation reaction proceed smoothly at room temperature. In addition to the fact that the reaction is carried out without the use of oxidation agents, a further advantage of this method is the possibility for operation in an aqueous electrolyte. Typically, aqueous sodium

•  24 [72]. In this example, 1,2-benzoquinone derivatives are generated in the presence of ketene N,O-acetals 70. Out of four possible regioisomers, 71a and 71b are exclusively formed (in ratios 71a/71b between 1:1 and 1:2). In a follow-up study, unreacted α-arylated ketene N,O-acetal intermediates (63

Design and synthesis of novel bis-annulated caged polycycles via ring-closing metathesis: pushpakenediol

• Sambasivarao Kotha and
• Mirtunjay Kumar Dipak

Beilstein J. Org. Chem. 2014, 10, 2664–2670, doi:10.3762/bjoc.10.280

• ] cycloaddition strategies, which involve the DA reaction of 2,5-dialkyl-1,4-benzoquinone 10 and 1,3-cyclopentadiene (9) followed by the formation of the cyclobutane ring through a [2 + 2] photocycloaddition reaction (Figure 2). Later on, one can introduce two allyl groups by using traditional carbonyl chemistry

• unsaturated component one can generate diverse PCUD ring systems. To realize the strategy depicted in Figure 2, we chose 2,5-diallyl-1,4-benzoquinone (18) as a viable option. We deliberately choose two unsaturated R groups at non-vicinal positions, because we have shown in an earlier report that the vicinal

• the corresponding 2,5-diallyl-1,4-benzoquinone (18) was obtained in good yield (67%). Since the quinone 18 is prone to polymerization (it gave a long streak on TLC when exposed to air at rt), it was immediately subjected to the [4 + 2] cycloaddition reaction with freshly prepared 1,3-cyclopentadiene

Synthesis of zearalenone-16-β,D-glucoside and zearalenone-16-sulfate: A tale of protecting resorcylic acid lactones for regiocontrolled conjugation

• Hannes Mikula,
• Julia Weber,
• Dennis Svatunek,
• Philipp Skrinjar,
• Gerhard Adam,
• Rudolf Krska,
• Christian Hametner and
• Johannes Fröhlich

Beilstein J. Org. Chem. 2014, 10, 1129–1134, doi:10.3762/bjoc.10.112

• dry DMF after optimization in terms of base and solvent type (Scheme 4A). Königs–Knorr glucosylation of the PMB-protected mimic 15 afforded 16, which was deprotected using 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) for oxidative PMB cleavage and subsequent ester saponification to yield the desired

The influence of intraannular templates on the liquid crystallinity of shape-persistent macrocycles

• Joscha Vollmeyer,
• Ute Baumeister and
• Sigurd Höger

Beilstein J. Org. Chem. 2014, 10, 910–920, doi:10.3762/bjoc.10.89

• catalysts and 1,4-benzoquinone as oxidant, the precursor is finally intramolecular cyclized in THF/piperidine under high-dilution conditions by slowly adding (48 hours) a solution of the tetraacetylene to the reaction media. Gel permeation chromatography (GPC) analysis of the crude product indicates that

• can be omitted. For this purpose, we performed the cyclization towards macrocycle 1c not under pseudo high-dilution conditions but by stirring a solution of the complete starting material of 1c at once in THF, piperidine, Pd(PPh3)Cl2 and CuI as catalysts and 1,4-benzoquinone as oxidant for 3 h at 60

• omitted for clarity); (c) visualization of the intraannular alkyl chain packing within the columns. Synthesis of macrocycle 1a with an intraannular undecanedioxy bridge. a: Pd(PPh3)2Cl2, PPh3, CuI, piperidine, 84%; b: TBAF, THF, 94%; c: Pd(PPh3)2Cl2, CuI, 1,4-benzoquinone, piperidine, THF, 49%. Synthesis

Synthesis of complex intermediates for the study of a dehydratase from borrelidin biosynthesis

• Frank Hahn,
• Nadine Kandziora,
• Steffen Friedrich and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 634–640, doi:10.3762/bjoc.10.55

• -dicyano-1,4-benzoquinone, Men = (l)-menthyl, DMP = Dess–Martin periodinane, TMS = trimethylsilyl. Synthesis of the BorDH3 substrates. a) Thiophenolpropionate, Cy2BCl, Me2EtN, Et2O, −78 °C to −20 °C, 16 h (57% over two steps from 12); b) HSNAc, Et3N, DMF, rt, 16 h (70%); c) THF/HCOOH/H2O (6:3:1), rt, 2 d