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

Muraymycin nucleoside-peptide antibiotics: uridine-derived natural products as lead structures for the development of novel antibacterial agents

• Daniel Wiegmann,
• Stefan Koppermann,
• Marius Wirth,
• Giuliana Niro,
• Kristin Leyerer and
• Christian Ducho

Beilstein J. Org. Chem. 2016, 12, 769–795, doi:10.3762/bjoc.12.77

• Bu4NBr resulted in bromohydrine 47, followed by levulinyl (Lev) protection of the hydroxy group (product 48). Nucleophilic substitution at the 6'-position with Bu4NN3 gave the naturally occurring (5'S,6'S)-stereochemistry of the uridine core structure in a double inversion manner [78][99]. DDQ oxidation

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

• by the reduction of the corresponding acetylated aldehydes or acids. Various stereoselective 1,2-trans-O-glycosylation methods were studied, including the DDQ–iodine or ZnO–ZnCl2 catalyst combination. Among them, ZnO–iodine has been identified as a new glycosylation promoter and successfully applied

• 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

• reactions in DCM promoted by Ag2O (Table 1, entry 1, 57%) and ZnO–I2 (Table 1, entry 4, 56%) gave comparably good yields. DDQ–I2 in ACN (Table 1, entry 3, 68%) gave 21b in the highest yield, in addition to the exclusive selectivity and the shortest reaction time (Table 1, entry 5). Therefore this promoter

Study on the synthesis of the cyclopenta[f]indole core of raputindole A

• Nils Marsch,
• Mario Kock and
• Thomas Lindel

Beilstein J. Org. Chem. 2016, 12, 334–342, doi:10.3762/bjoc.12.36

• –Schuster products could also be observed, but in small amounts and not as pure compounds. It is worth mentioning that treatment of 22 with DDQ led to removal of the DMB group, affording the major product 27 (23%) exhibiting a keto group in the benzylic indole position (Scheme 4). This transformation might

Recent developments in copper-catalyzed radical alkylations of electron-rich π-systems

• Kirk W. Shimkin and
• Donald A. Watson

Beilstein J. Org. Chem. 2015, 11, 2278–2288, doi:10.3762/bjoc.11.248

• dihydrofurans could be easily converted into furans using DDQ in a one-pot process. In addition to α-bromo esters and ketones, Lei and co-workers have also recently shown that benzylic halides could undergo radical alkenylation via copper catalysis [39]. By exploiting the propensity of benzyl halides to form

Easy access to heterobimetallic complexes for medical imaging applications via microwave-enhanced cycloaddition

• Nicolas Desbois,
• Sandrine Pacquelet,
• Adrien Dubois,
• Clément Michelin and
• Claude P. Gros

Beilstein J. Org. Chem. 2015, 11, 2202–2208, doi:10.3762/bjoc.11.239

• trifluoroacetic acid, followed by oxidation under the action of DDQ. Cu and Ga complexes were prepared by the strategy outlined in Scheme 2. The insertion of Cu into corrole 1 was easily achieved with Cu(OAc)2·H2O in THF during 15 min. To obtain the gallium corrole 8b, free-base azidocorrole 1 was dissolved in a

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

• required RRM product 208 was formed in 26% yield. Later, the expected chiral buckybowl 209 was assembled via aromatization of 208 in the presence of DDQ (Scheme 42). Design of intricate polyquinanes has been considered as a challenging task for synthetic chemists. To this end, Fallis and co-workers [46

Structure and conformational analysis of spiroketals from 6-O-methyl-9(E)-hydroxyiminoerythronolide A

• Ana Čikoš,
• Irena Ćaleta,
• Dinko Žiher,
• Mark B. Vine,
• Ivaylo J. Elenkov,
• Marko Dukši,
• Dubravka Gembarovski,
• Marina Ilijaš,
• Snježana Dragojević,
• Ivica Malnar and
• Sulejman Alihodžić

Beilstein J. Org. Chem. 2015, 11, 1447–1457, doi:10.3762/bjoc.11.157

• 3: 1H NMR (600 MHz, CDCl3) δ 0.85 (d, J = 7.3 Hz, 3H, 8-Me), 0.87 ( t, J = 7.3 Hz, 3H,15-H), 1.10 (s, 3H, 6-Me), 1.23 (d, J = 7.5 Hz, 3H, 4-Me), 1.27 (s, 3H, 12-Me), 1.32 (d, J = 7.2 Hz, 3H, 2-Me), 1.35 (ddq, J = 14.0, 11.9, 7.3 Hz, 1H, 14-H), 1.46 (dd, J = 14.1 Hz, 1H, 7-H), 1.66 (dqd, J = 14.0

• , 3H, 6-Me), 1.42 (ddq, J = 14.0, 11.0, 7.3 Hz, 1H, 14-H), 1.61 (dd, J = 12.4, 4.0 Hz, 1H, 7-H), 1.68 (dqd, J = 14.0, 7.3, 2.4 Hz, 1H, 14-H), 1.67–1.72 (m, 1H, 7-H), 1.72 (d, J = 1.6 Hz, 3H, 10-Me), 1.87 (dqd, J = 13.3, 6.7, 4.2 Hz, 1H, 8-H), 2.31 (q, J = 7.1 Hz, 1H, 4-H), 2.89 (dq, J = 7.5 Hz, 1H, 2-H

• ), 1.18 (s, 3H, 12-Me), 1.33 (s, 3H, 6-Me), 1.35 (ddq, J = 14.5, 11.3, 7.2 Hz, 1H, 14-H), 1.50 (dd, J = 12.7 Hz, 1H, 7-H), 1.62 (dd, J = 12.0, 3.7 Hz, 1H, 7-H), 1.67 (dqd, J = 14.0, 7.5, 2.4 Hz, 1H, 14-H), 1.66 (d, J = 1.6 Hz, 3H, 10-Me), 1.86 (dqd, J = 13.4, 6.6, 3.8 Hz, 1H, 8-H), 2.18 (qdd, J = 7.8, 3.0

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

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

• . Reagents and conditions: a) PhMe, reflux, 19 h, 74%; b) LiBr, NaBH4, THF, MeOH, −10 °C → rt, 20 h, 77%; c) PBr3, THF, 0 °C → rt, 20 h, 75%; d) (i) 13, MeCN, DMF, 80 °C, 15 min, (ii) Hg(OAc)2, CHCl3, AcOH, rt, 24 h, (iii) DDQ, PhCl, reflux, 4 h, 52% (from 12). Preparation of 7. Reagents and conditions: a

Glycoluril–tetrathiafulvalene molecular clips: on the influence of electronic and spatial properties for binding neutral accepting guests

• Yoann Cotelle,
• Marie Hardouin-Lerouge,
• Stéphanie Legoupy,
• Olivier Alévêque,
• Eric Levillain and
• Piétrick Hudhomme

Beilstein J. Org. Chem. 2015, 11, 1023–1036, doi:10.3762/bjoc.11.115

• onto compound 11 [34]. The hydroquinone moieties were subjected to a dehydrogenation reaction using DDQ in THF to reach desired glycolurildiquinone 13 [35] in 91% yield. The Diels–Alder cycloaddition was carried out by treatment of bis-dienophile 13 with TTF derivative 14 [36], able to give rise in

Discrete multiporphyrin pseudorotaxane assemblies from di- and tetravalent porphyrin building blocks

• Mirko Lohse,
• Larissa K. S. von Krbek,
• Sebastian Radunz,
• Suresh Moorthy,
• Christoph A. Schalley and
• Stefan Hecht

Beilstein J. Org. Chem. 2015, 11, 748–762, doi:10.3762/bjoc.11.85

• ), BF3·Et2O, DDQ, CHCl3, rt; b) Zn(OAc)2, CHCl3/MeOH, rt; c) dipyrromethane 6, BF3·Et2O, DDQ, CHCl3, rt; d) Zn(OAc)2, CHCl3/MeOH, rt; e) 1. benzylamine, trimethyl orthoformate, rt, 2. NaBH4, THF/MeOH, rt; f) Boc2O, triethylamine, CH2Cl2, rt; g) 1. ethynyltrimethylsilane, CuI, PPh3, Pd(PPh3)4, TEA

• , 3,4-dihydroxybenzaldehyde, DMF, 85 °C; d) 1. pyrrole (4), propionic acid, 140 °C, 2. Zn(OAc)2, MeOH/CHCl3, rt; e) 1. dipyrromethane (6), BF3·Et2O, DDQ, CHCl3, rt, 2. Zn(OAC)2, MeOH/CHCl3, rt. Supporting Information Supporting Information File 370: Detailed synthetic procedures. Acknowledgements The

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

• ([1,3]dithiolo[4,5-b][1,4]dithiinylidene) 52 – DDQ 53. Reaction conditions (i) (EtO)3P, 110 °C, N2, 2 h. Reaction conditions (i) EtOH, reflux, overnight; (ii) diisopropylethylamine in CH2Cl2, room temperature, overnight; (iii) (AcO)2Hg/AcOH, CHCl3, rt, 3h; iv) (EtO)3P, 110 °C, N2, 2 h; (v) sample in THF

A simple and efficient method for the preparation of 5-hydroxy-3-acyltetramic acids

• Johanna Trenner and
• Evgeny V. Prusov

Beilstein J. Org. Chem. 2015, 11, 323–327, doi:10.3762/bjoc.11.37

• DMB group with CAN [17] produced no product either. Successful removal of the DMB-protecting group from hydroxylated tetramic acid 16 and (trimethylsilyl)ethyl hemiaminal 19 was achieved upon treatment with an excess of DDQ in wet DCM. Treatment of the N-allyl-protected compound using catalytic

Photovoltaic-driven organic electrosynthesis and efforts toward more sustainable oxidation reactions

• Bichlien H. Nguyen,
• Robert J. Perkins,
• Jake A. Smith and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2015, 11, 280–287, doi:10.3762/bjoc.11.32

• ][25]. The reaction requires a careful balance between the initial condensation reaction and the oxidative step with either CAN or DDQ serving as the mediator. In the third reaction (Scheme 7), an intramolecular alcohol nucleophile was added to an olefin coupling reaction [26]. When a radical cation

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

• synthesized also from aromatic aldehydes, α,β-unsaturated aldehydes, or allylic alcohols in the presence of the DDQ (2,3-dichloro-5,6-dicyanobenzoquinone)/amberlyst-15 system in a methanol/toluene mixture under microwave irradiation [171]. Methyl, ethyl, and isopropyl benzoates were prepared from benzaldehyde

Articulated rods – a novel class of molecular rods based on oligospiroketals (OSK)

• Pablo Wessig,
• Roswitha Merkel and
• Peter Müller

Beilstein J. Org. Chem. 2015, 11, 74–84, doi:10.3762/bjoc.11.11

• , the PMB group was cleaved by DDQ to give the orthogonally protected trispiro rod 8 (Scheme 1). To demonstrate the capability of the approach outlined in Figure 3 we selectively activated both sides of building block 8 either by introduction of an azide group (9) or liberation of the terminal alkyne by

• –Martin-periodinane. iii: pentaerythritol, pTsOH (cat.). iv: 2-(4-methoxybenzyloxy)acetic acid, DCC, HOBt. v: (COCl)2/DMSO. vi: NaH, TMSCl, TMSOTf, vii DDQ, DCM, buffer pH 7). Synthesis of articulated rod 11 (i: CBr4, PPh3, NaN3. ii: K2CO3/MeOH. iii: Cu/C DCM/MeOH 1:1, cat. Et3N). Sequential deprotection

• of 11 and synthesis of triple articulated rod 14 (i: K2CO3/MeOH. ii: CBr4/PPh3/NaN3.iii: Cu/C, Et3N. iv: CBr4/PPh3/NaN3.). Synthesis of articulated rods 23–25 with increased solubility (i: 4-hydroxypiperidine, DCC, HOBt. ii: (COCl)2/DMSO. iii: 6, NaH, TMSCl, TMSOTf. iv: DDQ. v: K2CO3/MeOH. vi: CBr4

Efficient deprotection of F-BODIPY derivatives: removal of BF₂ using Brønsted acids

• Mingfeng Yu,
• Joseph K.-H. Wong,
• Cyril Tang,
• Peter Turner,
• Matthew H. Todd and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2015, 11, 37–41, doi:10.3762/bjoc.11.6

• and conditions: (a) (i) 2,4-dimethyl-1H-pyrrole (5), TFA, DCM, rt, overnight; (ii) DDQ, rt, 2 h; (iii) Et3N, BF3·OEt2, rt, overnight, 27%; (b) NH2NH2·H2O, 10% Pd/C, EtOH, reflux, 2 h, 90%; (c) (i) 1 M HCl (aq), CH3OH, NaNO2, H2O, 0 °C, 1 h; (ii) NaN3, H2O, rt, 2 h, 71%; (d) propargyl-tri-Boc cyclam 12

• , CuSO4·5H2O, sodium ascorbate, THF/H2O (7:3), 50 °C, 12 h, 100%; (e) trimethylsilylacetylene, CuI, Pd(PPh3)4, Et3N, THF, rt, overnight, 100%; (f) K2CO3, CH3OH, rt, overnight, 71%; (g) (i) 2,4-dimethyl-1H-pyrrole (5), TFA, DCM, rt, overnight; (ii) DDQ, rt, 2 h; (iii) Et3N, BF3·OEt2, rt, overnight, 24%; (h

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

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

• converted with α- and β-pinene to form euglobal model compounds 55 and 56. The electrolysis was carried out in an undivided cell under potentiostatic conditions with a CH3NO2/Et4NOTs electrolyte. DDQ was employed as a redox mediator, allowing for operation at a relatively low electrode potential of 0.45 V

Solution processable diketopyrrolopyrrole (DPP) cored small molecules with BODIPY end groups as novel donors for organic solar cells

• Diego Cortizo-Lacalle,
• Calvyn T. Howells,
• Upendra K. Pandey,
• Joseph Cameron,
• Neil J. Findlay,
• Anto Regis Inigo,
• Tell Tuttle,
• Peter J. Skabara and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2683–2695, doi:10.3762/bjoc.10.283

• ). Compound 6 was prepared by acid-catalysed condensation of 5-bromothiophene-2-carbaldehyde with 3-ethyl-2,4-dimethylpyrrole, followed by oxidation with DDQ. Deprotonation with triethylamine and subsequent treatment with boron trifluoride diethyl etherate yielded 6. The entire synthesis was carried out as a

• -dimethylformamide, rt, 16 h, 88%; (iii) trifluoroacetic acid, dichloromethane, rt, 16 h; DDQ, rt, 24 h; triethylamine, BF3·OEt2, rt, 24 h, 33% and 12% for 6 and 7, respectively; (iv) DPP 8, Pd2(dba)3, tri-tert-butylphosphonium tetrafluoroborate, THF/water, tripotassium phosphate, reflux, 48 h, 55% and 34% for 9 and

Expanding the scope of cyclopropene reporters for the detection of metabolically engineered glycoproteins by Diels–Alder reactions

• Anne-Katrin Späte,
• Verena F. Schart,
• Julia Häfner,
• Andrea Niederwieser,
• Thomas U. Mayer and
• Valentin Wittmann

Beilstein J. Org. Chem. 2014, 10, 2235–2242, doi:10.3762/bjoc.10.232

• purification of the β-anomer. Retention time β-anomer: 15 min, α-anomer: 16.5 min. β-Anomer: 1H NMR (400 MHz, CDCl3) δ 6.54 (s, 1H, =CH), 5.72 (d, J = 8.7 Hz, 1H, H-1), 5.39 (dd, J = 3.6, 1.1 Hz, 1H, H-4), 5.10 (ddq, J = 11.4, 3.4, 1.4 Hz, 1H, H-3), 4.61–4.48 (m, 1H, NH), 4.14 (qd, J = 11.3, 6.6 Hz, 3H, H-2, H

Synthesis and bioactivity of analogues of the marine antibiotic tropodithietic acid

• Patrick Rabe,
• Tim A. Klapschinski,
• Nelson L. Brock,
• Christian A. Citron,
• Paul D’Alvise,
• Lone Gram and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2014, 10, 1796–1801, doi:10.3762/bjoc.10.188

• . Oxidative cleavage of the glycol with NaIO4 resulted in a β-ketoester aldehyde that upon treatment with silica gel underwent an intramolecular aldol condensation to a mixture of 10a and 11a that were separable by column chromatography. Oxidation with DDQ gave tert-butyl tropone-2-carboxylate (12a) that was

• treated under various oxidation conditions (including DDQ, IBX, SeO2, and MnO2) to install the tropone moiety by dehydrogenation, but unfortunately all these reaction conditions failed. Compound 22 was subsequently converted into the free acid 23 by treatment with TFA, while similar conversions of 20 and

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

• glucoside 17 in an overall yield of 30% (Scheme 4B). Applying this procedure to ZEN (1) afforded the glucosylated intermediate 19 after Königs–Knorr glucosylation of 14-PMB-ZEN (18), but subsequent deprotection using DDQ did not afford the desired product. Also an alternative procedure for oxidative PMB

• . Since the DDQ-promoted cleavage of phenolic PMB ethers can be complicated by overoxidation, especially with electron-rich phenolic compounds [35], we assume a significant effect of the conjugated olefinic double bond at C-6’ of the resorcylic acid moiety being responsible for the observed different

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

• ]. a) DDQ, CH2Cl2, rt, 30 min (85%); b) DMP, CH2Cl2, rt, 2 h; c) NaOCl, 2-methyl-2-butene, t-BuOH, phosphate buffer, rt, 16 h; d) TMS-CHN2, toluene/MeOH 2:3, rt, 40 min (58% over three steps); e) second generation Grubbs catalyst, crotonaldehyde, CH2Cl2, 40 °C, 120 min (88%); DDQ = 2,3-dichloro-5,6

An oxidative amidation and heterocyclization approach for the synthesis of β-carbolines and dihydroeudistomin Y

• Suresh Babu Meruva,
• Akula Raghunadh,
• Raghavendra Rao Kamaraju,
• U. K. Syam Kumar and
• P. K. Dubey

Beilstein J. Org. Chem. 2014, 10, 471–480, doi:10.3762/bjoc.10.45

• , whereas the OH proton in 8a shows a high nOe (Scheme 6). Dihydro-β-carboline 7 was then subjected to an aromatization reaction to obtain eudistomin Y (6). The aromatization reaction was attempted with oxidizing agents such as DDQ and MnO2 as per the reported conditions in literature. The formation of