A versatile route to polythiophenes with functional pendant groups using alkyne chemistry

• Xiao Huang,
• Li Yang,
• Rikard Emanuelsson,
• Jonas Bergquist,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 2682–2688, doi:10.3762/bjoc.12.265

• synthesis exclude the use of pendant groups featuring electrophilic or nucleophilic functional moieties, such as esters and alkyl halide, or alcohols and phenols. Furthermore, in the case of EDOT-CH2-Cl/Br, the α-hydrogen on the ethylene bridge is acidic and it thus favors β-elimination under basic

Solvent-free, visible-light photocatalytic alcohol oxidations applying an organic photocatalyst

• Martin Obst and
• Burkhard König

Beilstein J. Org. Chem. 2016, 12, 2358–2363, doi:10.3762/bjoc.12.229

• solvent like hydrogen-atom transfer or the formation of byproducts could be excluded. For liquid substrates, some examples for photocatalytic, solvent-free conversions are reported, such as the oxidation of benzyl alcohol to benzaldehyde [4] and the oxidation of benzenes to phenols [5]. Another field of

Tunable microwave-assisted method for the solvent-free and catalyst-free peracetylation of natural products

• Manuela Oliverio,
• Paola Costanzo,
• Monica Nardi,
• Carla Calandruccio,
• Raffaele Salerno and
• Antonio Procopio

Beilstein J. Org. Chem. 2016, 12, 2222–2233, doi:10.3762/bjoc.12.214

• , phenols and amino groups is a classical protection method in multistep syntheses as well as a transient chemical modification to improve the bioavailaibility and bioactivity of hydrophilic drugs and natural polyols [1][2][3][4][5][6][7][8][9]. Several in vitro and in vivo studies on peracetylated

• ]. Classically peracetylation reactions have been performed by treatment of alcohols and phenols with acid anhydrides or acid chlorides in the presence of bases [12]. Recently, the urgency to find more environmental benign methods for standard transformations, led to the optimization of methods employing

• applied to alcohols, phenols and polyols characterized by a huge chemical diversity and thermostability, simply tuning the MW settings. Such method is potentially universally applicable for green acetylation of hydrophilic biological molecules, thus improving their bioavailability and biological activity

Superelectrophilic activation of 5-hydroxymethylfurfural and 2,5-diformylfuran: organic synthesis based on biomass-derived products

• Dmitry S. Ryabukhin,
• Dmitry N. Zakusilo,
• Mikhail O. Kompanets,
• Anton A.Tarakanov,
• Irina A. Boyarskaya,
• Tatiana O. Artamonova,
• Mikhail A. Khohodorkovskiy,
• Iosyp O. Opeida and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 2125–2135, doi:10.3762/bjoc.12.202

• molecules, such as alcohols, carboxylic acids, (hetero)aromatic ketones and aldehydes, phenols, etc. These biomass-derived platform chemicals are considered as an alternative and displacement to petroleum chemistry [17][18]. Among all these compounds, the preparation and reaction of 5-hydroxymethylfurfural

Diastereoselective synthesis of 3,4-dihydro-2H-pyran-4-carboxamides through an unusual regiospecific quasi-hydrolysis of a cyano group

• Mikhail Yu. Ievlev,
• Oleg V. Ershov,
• Mikhail Yu. Belikov,
• Angelina G. Milovidova,
• Viktor A. Tafeenko and
• Oleg E. Nasakin

Beilstein J. Org. Chem. 2016, 12, 2093–2098, doi:10.3762/bjoc.12.198

• convenient methods for the construction of 3,4-dihydro-2H-pyrans are based on the interaction between ylidene derivatives of methylene-active compounds and β-oxo derivatives of acids or ketones [9][10][11], and also on the reactions of phenols with carbonyl compounds [12]. An interesting example that had

The in situ generation and reactive quench of diazonium compounds in the synthesis of azo compounds in microreactors

• Faith M. Akwi and
• Paul Watts

Beilstein J. Org. Chem. 2016, 12, 1987–2004, doi:10.3762/bjoc.12.186

• synthesis and to see if the size effect had any major implication on the reaction performance. Results and Discussion Azo coupling reaction in the synthesis of 1-((2,4-dimethylphenyl)azo)naphthalen-2-ol in LTF-MS microreactors In an effort to exemplify the azo coupling of phenols as well as naphthol

• is also dependent on the kind of coupling compound used [31]. For example, phenols are successfully coupled in alkaline conditions in which the phenolate ion is formed. These conditions provide the desired electron-releasing group thus facilitating the electrophilic substitution reaction to afford

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• ionic liquid increases the catalytic activity of dibutyltin oxide fourfold probably by forming a highly active tin species where the anion of the ionic liquid acts as a ligand. The developed protocol was further studied for various substituted phenols, proving that electron-donating groups (EDG) at the

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• the synthesis of functionalized ketones and alcohols, including γ-hydroxy enones. The Dakin oxidation finds application for the synthesis of phenols from arylaldehydes or aryl ketones and the Elbs persulfate oxidation allows the preparation of hydroxyphenols from phenols. Finally, the Schenck and

• studies on this topic [196][239][240][241][242][243][244][245][246]. Hydroxylated and methoxylated benzaldehydes 69 (Scheme 21) and acetophenones 72 (Scheme 22) can be oxidized to the corresponding phenols 70a–d, and 73 in good yields in the presence of the H2O2/MeReO3 system in ionic liquids [bmim]BF4 or

• peroxides (Scheme 61) [331]. The direct dehydrogenative construction of C–N bonds between unprotected phenols 215 and a series of 10H-phenoxazines and 10H-phenothiazines 214 with formation of 216 was carried out using a Hock-like activation with O2 followed by amine oxidation (Scheme 62) [332]. The Hock

Catalytic Chan–Lam coupling using a ‘tube-in-tube’ reactor to deliver molecular oxygen as an oxidant

• Carl J. Mallia,
• Paul M. Burton,
• Alexander M. R. Smith,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1598–1607, doi:10.3762/bjoc.12.156

• active compounds [11][12]. In 2009 the groups of Stevens and van der Eycken reported on the Chan–Lam reaction as a continuous flow protocol using copper(II) acetate (1.0 equiv), pyridine (2.0 equiv) and triethylamine (1.0 equiv) in dichloromethane [13]. Generally, when using anilines or phenols as the

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

• Franziska Hemmerling and
• Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

• biosynthesis in Antirrhinum majus [152][153]. It catalyses the oxidation of phenols 180 and o-catechols 181 to o-quinones 182 and concomitant conjugate addition of a phenolic hydroxy group, leading to the formation of the central furan-3-one unit [154]. This enzyme is flavin-dependent and acts under

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• -catalyzed addition of potassium organotrifluoroborates 49 to α-aminoacrylates 52 to access phenylalanine derivatives 54 (Scheme 12) [33]. The authors identified guaiacol (53) as the optimal proton source, observing the general trend that less acidic phenols led to an increase in enantioselectivity. A wide

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• also been studied for the total synthesis of natural products and accessing biologically important scaffolds. In 2012, Bisai et al. reported the Lewis acid-catalyzed Friedel–Crafts alkylation of 3-hydroxy-2-oxindoles with electron-rich phenols (Scheme 46) [63]. They found that various Lewis acids (e.g

• ., Sc(OTf)3, In(OTf)3, Zn(OTf)2, FeCl3, etc) can catalyze the reactions to give 3,3-disubstituted oxindoles in moderate to excellent yields and with excellent regioselectivities. For para-substituted phenols, the reactions gave the corresponding ortho-substituted products. While for para-unsubstituted

• phenols, the reactions exclusively gave the para-substituted products. Mechanistically, in the presence of a catalytic amount of Lewis acid, the 3-hydroxyoxindole was converted to the intermediate A through dehydration, which was then tapped by the electron-rich phenol. para-Substituted products were

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

• increases their water solubility. Further it influences the physicochemical and pharmacological properties of these phenols and often reduces their potential toxicity. Moreover, p-hydroxyarylalkyl glycosides are also key starting building blocks for the synthesis of more complex bioactive natural compounds

Scope and limitations of the dual-gold-catalysed hydrophenoxylation of alkynes

• Adrián Gómez-Suárez,
• Yoshihiro Oonishi,
• Anthony R. Martin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2016, 12, 172–178, doi:10.3762/bjoc.12.19

• as nitriles, ketones, esters, aldehydes, ketals, naphthyls, allyls or polyphenols, in a milder and more efficient manner than the previously reported methodologies. We have also identified that while we are able to use highly steric hindered phenols, small changes on the steric bulk of the alkynes

• our transformation? How do steric and electronic factors affect both reaction partners? Can regioselectivity be achieved for the addition of phenols to unsymmetrical alkynes? Results and Discussion Functional group tolerance We commenced our studies by assessing the functional group tolerance of the

• methodology (Scheme 2). With that aim we reacted diphenylacetylene (1a) with several phenols, 2a–o, in toluene, using 0.5 mol % of [{Au(IPr)}2(µ-OH)][BF4] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) as the catalyst. Functional groups such as nitriles (3aa), ketones (3ab), esters (3ac), aldehydes

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

• the Czech Republic, Vídeňská 1083, 142 20 Prague, Czech Republic 10.3762/bjoc.12.12 Abstract Oxidation of 3- and 4-pentafluorosulfanyl-substituted anisoles and phenols with hydrogen peroxide and sulfuric acid provided a mixture of SF5-substituted muconolactone, maleic, and succinic acids. A plausible

• using 85% H3PO4 at 100 °C, levulinic acid 18 was obtained in 14% yield. This result allowed us to propose that byproduct 5 observed during oxidation of SF5-anisoles and phenols could be formed from open-chain acids according to Scheme 7. Despite the lack of efficient synthetic protocols toward maleic

Determination of formation constants and structural characterization of cyclodextrin inclusion complexes with two phenolic isomers: carvacrol and thymol

• Miriana Kfoury,
• David Landy,
• Steven Ruellan,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2016, 12, 29–42, doi:10.3762/bjoc.12.5

• ]. They are generally recognized as safe (GRAS), approved by the US Food and Drug Administration for human consumption and included by the Council of Europe in the list of food flavorings [1][2]. These phenols are traditionally used at low concentrations as flavoring agents in food [3] and do not have any

• −1) [28]. The obtained Kf value is in good agreement with our results (Table 1). Compounds 1 and 2 differ only by the position of the hydroxy group on the aromatic cycle (Figure 1). Results showed that encapsulation of 1 and 2 occurred with all the six CDs. Nonetheless, both phenols were more readily

• competitive UV–visible method. However, for both phenols, HP-β-CD did not give lower Kf values compared to β-CD as observed with the UV–visible competitive method. This could be explained by the better solubilizing potential of the β-CD derivative compared to the native one. Indeed, Kf values obtained from

Facile synthesis of 4H-chromene derivatives via base-mediated annulation of ortho-hydroxychalcones and 2-bromoallyl sulfones

• Srinivas Thadkapally,
• Athira C. Kunjachan and
• Rajeev S. Menon

Beilstein J. Org. Chem. 2016, 12, 16–21, doi:10.3762/bjoc.12.3

• % yield (Scheme 2). It may be noted that these reaction conditions were developed for the reaction of 2a with phenols (see Scheme 1, paths b and c) [24]. In the 1H NMR spectrum of 8aa, three sets of doublet of doublets were visible at δ 4.52 (1H, J = 2.3 and 9.0 Hz), δ 3.58 (1H, J = 2.3 and 17.1 Hz) and δ

• extend the annulation reaction to phenols with other Michael acceptors at the ortho-position (such as unsaturated esters, enals and nitroolefins) were not successful. Additionally, a very low yield (ca. 10%) of the product 8aa was obtained when the chalcone formation (7a) and its annulation reaction with

C–H bond halogenation catalyzed or mediated by copper: an overview

• Wenyan Hao and
• Yunyun Liu

Beilstein J. Org. Chem. 2015, 11, 2132–2144, doi:10.3762/bjoc.11.230

• and 2-phenyl-1,3,4-oxadiazole were smoothly iodinated to provide iodoheteroarenes 18 (Scheme 10) [45]. As typical electron-enriched arenes, phenols and analogous arenes tend to undergo a single-electron transfer process [46], the property of these arenes also resulted in sound attention to their C–H

• halogenations. In 2006, Gusevskaya and Menini [47][48] reported a highly selective method for C–H chlorination and bromination of various phenols under aerobic, copper-catalyzed conditions. As displayed in Scheme 11, the reaction of phenols 19 with 2 equiv of LiCl in the prensence of O2 and 12.5 mol % CuCl2 in

• modified catalytic conditions (Scheme 11). However, it was found that the oxidative bromination of phenols exhibited generally lower para regioselectivity than the corresponding chlorination [49]. Mechanistic studies on these reactions indicated that the halogenation reactions proceeded via a free radical

Antioxidant potential of curcumin-related compounds studied by chemiluminescence kinetics, chain-breaking efficiencies, scavenging activity (ORAC) and DFT calculations

• Adriana K. Slavova-Kazakova,
• Silvia E. Angelova,
• Timur L. Veprintsev,
• Petko Denev,
• Davide Fabbri,
• Maria Antonietta Dettori,
• Maria Kratchanova,
• Vladimir V. Naumov,
• Aleksei V. Trofimov,
• Rostislav F. Vasil’ev,
• Giovanna Delogu and
• Vessela D. Kancheva

Beilstein J. Org. Chem. 2015, 11, 1398–1411, doi:10.3762/bjoc.11.151

• the kinetic solvent effect of water is of great importance in this case. Hydrogen bonding can have a profound influence on the activity of phenols as antioxidants. It is generally recognized [28][29][30] that solvent effects and especially the ionization effect of the medium may alter the mechanism of

Azobenzene-based inhibitors of human carbonic anhydrase II

• Leander Simon Runtsch,
• David Michael Barber,
• Peter Mayer,
• Michael Groll,
• Dirk Trauner and
• Johannes Broichhagen

Beilstein J. Org. Chem. 2015, 11, 1129–1135, doi:10.3762/bjoc.11.127

• enzyme affinity. Results and Discussion Azobenzenes can be synthesized by a variety of known chemical transformations [8]. Among them the most widely used is the diazotization of aniline, followed by trapping of the diazonium salt with an electron-rich aromatic compound (such as anilines and phenols

Highly selective generation of vanillin by anodic degradation of lignin: a combined approach of electrochemistry and product isolation by adsorption

• Dominik Schmitt,
• Carolin Regenbrecht,
• Marius Hartmer,
• Florian Stecker and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2015, 11, 473–480, doi:10.3762/bjoc.11.53

• . Electrolysis conditions are optimized regarding reaction temperatures below 100 °C allowing operation of aqueous electrolytes in simple experimental set-up. Employing ion exchange resins gives rise to a selective removal of low molecular weight phenols from the strongly alkaline electrolyte without

• related phenols from the alkaline electrolyte. An easy to perform enrichment of the desired product by adsorption at strongly basic anion exchange resins was established. The larger lignin particles were not bound to the gel-type resins because the size exclusion effect does not affect them. Only small

Matsuda–Heck reaction with arenediazonium tosylates in water

• Ksenia V. Kutonova,
• Marina E. Trusova,
• Andrey V. Stankevich,
• Pavel S. Postnikov and
• Victor D. Filimonov

Beilstein J. Org. Chem. 2015, 11, 358–362, doi:10.3762/bjoc.11.41

• , entry 9) and 2i (Table 2, entry 10), which proofed to be less reactive, so that the complete conversion was only achieved with 2.5 mol % of palladium diacetate. No side-products were detected including phenols (as monitored by GC–MS and HPLC). The latter are often formed if diazonium salts take part in

Natural phenolic metabolites with anti-angiogenic properties – a review from the chemical point of view

• Qiu Sun,
• Jörg Heilmann and
• Burkhard König

Beilstein J. Org. Chem. 2015, 11, 249–264, doi:10.3762/bjoc.11.28

• concentrations in many fruits and vegetables, resulting in a continuous and long-term intake of such plant phenols. Consequently, their beneficial and protective impact on unbalanced angiogenic processes has been intensively discussed [7][8]. In the last decade, many excellent review articles summarized the

• , epigallocatechin-3-O-gallate, xanthohumol, (2S)-7,2’,4’-trihydroxy-5-methoxy-8-dimethylallylflavanone and genistein. Other compounds belong to the group of simple phenols (4-hydroxybenzyl alcohol), hydrolysable tannins (ellagic acid), stilbenoids (resveratrol) and diarylheptanoids (curcumin). In addition

• , acylphloroglucinols, quinolone-substituted phenols and 4-amino-2-sulfanylphenol derivatives are discussed. Some important aspects of the described pharmacological activities of the compounds are summarized in Table 3. Review 4-Hydroxybenzyl alcohol 4-Hydroxybenzyl alcohol (HBA, 1) (Figure 1) is a well-known phenolic

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

• /CH-reagent was 1:1 for aromatic OH-reagents and 5:1 for aliphatic alcohols. Different organic and inorganic bases were used depending on the structures of substrates. The cross-dehydrogenative coupling of phenols and arenes 61 with a directing group containing a pyridine N-oxide moiety occurs in the

• quinone 116 afforded esters 117. This method was also applied to the synthesis of esters 117a–c from amino alcohols (Scheme 25) [115][116]. Different conditions were proposed for the cross-dehydrogenative C–O coupling of aldehydes with alcohols and phenols catalyzed by N-heterocyclic carbenes (118, 129

• works, the oxidative coupling of alcohols, aldehydes, or formamides with 1,3-dicarbonyl compounds or phenols was accomplished in the presence of tert-butyl hydroperoxide and copper salts (Table 5). In most cases, the range of phenols applicable to the coupling is limited to 2-acylphenols. However, 2

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

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

• of 2,3-dihydrobenzofuran structures 43 via double-mediatory Wacker-type cyclization of alkenyl phenols 42 [61]. Pd(OAc)2 was used to catalyze the cyclization while TEMPO served as redox mediator for the electrochemical regeneration of the catalytically active Pd(II) species. In contrast to

• phenols [78][79], they could observe the formation of spiropentacyclic scaffold 76 (Scheme 29) as byproduct of the electrolysis of 2,4-dimethylphenol (72) [80]. Later it turned out that compound 73 (a dehydrotetramer of 72) is the actual electrolysis product, which reacted to 76 via thermal rearrangement

• ). Electrosynthesis of 39 as part of the total synthesis of alkaloids 40 and 41. Wacker-type cyclization of alkenyl phenols 42. Cathodic synthesis of indol derivatives. Fluoride mediated anodic cyclization of α-(phenylthio)acetamides. Synthesis of 2-substituted benzoxazoles from Schiff bases. Synthesis of euglobal