Supercritical carbon dioxide: a solvent like no other

• Jocelyn Peach and
• Julian Eastoe

Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196

• was significantly less pronounced than those seen in water-in-oil systems [94]. AOT surfactant organogels have also been induced in isooctane through the addition of trace levels of para-substituted phenols (p-ethylphenol and p-methylphenol, Figure 8), with reports of vast viscosity enhancements up to

• hydrotropic salts and phenols to microemulsions can lead to positive viscosity builds in both water-in-oil and water-in-carbon dioxide systems as observed by Eastoe et al. and John et al. [40][94][104] Emerging areas using supercritical CO2 Bicontinuous and lamellar phases, lamellar liquid crystals and foams

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

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

• be formed by rearrangement of 11 when activated in the presence of a weak acceptor (Scheme 2B) [31][32][33][34]. Königs–Knorr glucosylation, which in general is most frequently used for the glucosylation of phenols, using commercially available bromo sugar 13 activated by silver(I) salts or under

Olefin cross metathesis based de novo synthesis of a partially protected L-amicetose and a fully protected L-cinerulose derivative

• Bernd Schmidt and
• Sylvia Hauke

Beilstein J. Org. Chem. 2014, 10, 1023–1031, doi:10.3762/bjoc.10.102

• decomposition to isomerization active species. This phenomenon has often been observed for second generation catalysts [53]. For these reasons, phenol was used as a rate accelerating additive. Phenols are believed to coordinate to the Ru and stabilize the catalytically active 14-electron species, resulting in a

A convenient enantioselective decarboxylative aldol reaction to access chiral α-hydroxy esters using β-keto acids

• Zhiqiang Duan,
• Jianlin Han,
• Ping Qian,
• Zirui Zhang,
• Yi Wang and
• Yi Pan

Beilstein J. Org. Chem. 2014, 10, 969–974, doi:10.3762/bjoc.10.95

• one point-binding aldehydes and two-point binding β-keto acids under mild reaction conditions. The lack of strong Lewis acids or very basic intermediates enabled it to tolerate functionalities that would normally be incompatible with ester enolates, for instance, hydroxy groups, phenols, enolizable

Unusual polymorphism in new bent-shaped liquid crystals based on biphenyl as a central molecular core

• Anna Kovářová,
• Svatopluk Světlík,
• Václav Kozmík,
• Jiří Svoboda,
• Vladimíra Novotná,
• Damian Pociecha,
• Ewa Gorecka and
• Natalia Podoliak

Beilstein J. Org. Chem. 2014, 10, 794–807, doi:10.3762/bjoc.10.75

• compatible with the applied reaction conditions, thus, we switched to the benzyl protection of the hydroxy group (acid 1b and 2). The requested lengthening arms for the synthesis of materials of series I–III involved two-ring phenols 3–5 and substituted benzoic acids 6a–c (Figure 1). For the preparation of

• series of materials IV–VI, we utilized lengthening arms of phenols 7a–c and two-ring acids 8–10. All intermediates were obtained previously by known methods [47][48][49]. The bent-shaped liquid crystals I–III were synthesized in three steps (Scheme 1). The protected acids 1a,b were esterified with

• phenols 3–5 in the presence of N,N'-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP) to yield esters 11–13 (Scheme 1). The methoxycarbonyl group in 11 was subsequently removed by means of aq. ammonia and the benzyl group in 12 and 13 by a palladium-catalysed transfer-hydrogenation. The

Visible-light photoredox catalysis enabled bromination of phenols and alkenes

• Yating Zhao,
• Zhe Li,
• Chao Yang,
• Run Lin and
• Wujiong Xia

Beilstein J. Org. Chem. 2014, 10, 622–627, doi:10.3762/bjoc.10.53

• of phenols and alkenes has been developed utilizing visible light-induced photoredox catalysis. The bromine was generated in situ from the oxidation of Br− by Ru(bpy)33+, both of which resulted from the oxidative quenching process. Keywords: alkenes; bromination; phenols; photoredox catalyst

• phenols. The typical approaches include direct electrophilic halogenation by using molecular bromine or N-bromosuccinimide (NBS) [6][7][8], organometallic catalyst-promoted bromination [9][10][11][12], and the oxidative bromination of phenols [13][14][15]. Nevertheless, most of the methods suffer from

• several drawbacks such as toxic reagents, harsh conditions, low yields, and low chemo- and regioselectivity. Hence, the development of an environmentally friendly methodology for the bromination of phenols with high chemoselectivity under mild and operationally simple conditions is still appealing

New sesquiterpene hydroquinones from the Caribbean sponge Aka coralliphagum

• Qun Göthel and
• Matthias Köck

Beilstein J. Org. Chem. 2014, 10, 613–621, doi:10.3762/bjoc.10.52

• halenaquinol sulfate from the marine sponge Xestospongia sapra [14]. In the course of our investigation on the sponge Aka coralliphagum, we isolated a number of compounds containing sulfated phenols. These sulfated metabolites are labile [5], and easily loose the sulfate ester groups by hydrolysis in water [15

Diversity-oriented synthesis of dihydrobenzoxazepinones by coupling the Ugi multicomponent reaction with a Mitsunobu cyclization

• Lisa Moni,
• Luca Banfi,
• Andrea Basso,
• Alice Brambilla and
• Renata Riva

Beilstein J. Org. Chem. 2014, 10, 209–212, doi:10.3762/bjoc.10.16

• reactions [2], especially the intramolecular Mitsunobu reaction of alcohols with phenols or sulfonamides. By exploiting a single post-MCR transformation (the Mitsunobu reaction) it is possible to obtain several diverse heterocyclic scaffolds by installing the two additional groups in any of the four

3-Pyridinols and 5-pyrimidinols: Tailor-made for use in synergistic radical-trapping co-antioxidant systems

• Luca Valgimigli,
• Daniele Bartolomei,
• Riccardo Amorati,
• Evan Haidasz,
• Jason J. Hanthorn,
• Susheel J. Nara,
• Johan Brinkhorst and
• Derek A. Pratt

Beilstein J. Org. Chem. 2013, 9, 2781–2792, doi:10.3762/bjoc.9.313

• stronger O–H bonds than equivalently substituted phenols, but possess similar reactivities toward autoxidation chain-carrying peroxyl radicals. These attributes suggest that 3-pyridinols and 5-pyrimidinols will be particularly effectiveco-antioxidants when used in combination with more common, but less

• reactive phenols to regenerate them from their corresponding aryloxyl radicals. The present investigations were carried out in chlorobenzene and acetonitrile in order to provide some insight into the medium dependence of the synergism and the results, considered with some from our earlier work, prompt a

• phenolic antioxidants, but which are equally efficacious as the 3-pyridinol/5-pyrimidinol antioxidants alone at higher loadings. Keywords: antioxidants; autoxidation; free radical; phenols; 3-pyridinols; 5-pyrimidinols; Introduction Radical-trapping (chain-breaking) antioxidants are arguably the most

Halogenated volatiles from the fungus Geniculosporium and the actinomycete Streptomyces chartreusis

• Tao Wang,
• Patrick Rabe,
• Christian A. Citron and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 2767–2777, doi:10.3762/bjoc.9.311

• ) [25] or the trichlorinated phenols 20–22 (Figure 5) [26]. The biological function of 4b and 10b in Geniculosporium is unknown, but the antibiotic activity of the related compound drosophilin A towards bacteria is well known [27]. A iodinated volatile from Streptomyces chartreusis During the course of

Stereoselectively fluorinated N-heterocycles: a brief survey

• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2013, 9, 2696–2708, doi:10.3762/bjoc.9.306

• to be successfully achieved. One such reagent, PhenoFluor (45, Figure 12), was originally developed by Ritter and co-workers for the direct fluorination of phenols [56]. Recent work showed that 45 can also be used to effect late-stage fluorination of hydroxy groups within complex molecular

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• process for the formation of new C–O bonds. In this direction numerous examples of metal and Brønsted-acid catalyzed condensations of alcohols, phenols and carboxylic acids to inactivated olefins have been reported [16]. Interestingly, He and co-workers compared the catalytic attitude of TfOH and

• works, Yang and He reported on the Ph3PAuOTf assisted Markovnikov-like addition of phenols and carboxylic acids to C=C under mild reaction conditions (Scheme 1) [27]. Electron-rich and electron-poor phenols reacted smoothly in toluene (85 °C) with only 1 mol % of catalyst loading (Scheme 1a). Contrarily

• , carboxylic acids required a higher loading of catalyst (5 mol %), but an acceptable yield was obtained even when sterically demanding 2-methylpropionic acid was employed as the nucleophile (Scheme 1b). Li and co-workers exploited the [Au(III)]-catalyzed addition of phenols and naphthols to conjugated dienes

Ambient gold-catalyzed O-vinylation of cyclic 1,3-diketone: A vinyl ether synthesis

• Yumeng Xi,
• Boliang Dong and
• Xiaodong Shi

Beilstein J. Org. Chem. 2013, 9, 2537–2543, doi:10.3762/bjoc.9.288

• vinyl ether synthesis using gold has been reported to date [17]. Nevertheless, there have been examples regarding the intermolecular addition of carboxylic acids [19][20], phenols [21][22] as well as phosphoric acids [23][24][25] to alkynes. In this context, we report a gold(I)-catalyzed O-vinylation of

Flexible synthesis of anthracycline aglycone mimics via domino carbopalladation reactions

• Markus Leibeling and
• Daniel B. Werz

Beilstein J. Org. Chem. 2013, 9, 2194–2201, doi:10.3762/bjoc.9.258

• oxidative procedures provided only the mono-oxidized products in trace amounts [40][41][42]. The oxidation of phenyl-substituted silanes to respective phenols is difficult [43][44]. However, literature precedence revealed that benzyl-substituted silane 13c or electron-deficient silane 13d [43][45] should be

Gold(I)-catalyzed hydroarylation reaction of aryl (3-iodoprop-2-yn-1-yl) ethers: synthesis of 3-iodo-2H-chromene derivatives

• Pablo Morán-Poladura,
• Eduardo Rubio and
• José M. González

Beilstein J. Org. Chem. 2013, 9, 2120–2128, doi:10.3762/bjoc.9.249

• Starting materials 1 were obtained from the corresponding phenols through a two steps synthetic route. General procedure for the propargylation of phenols To a suspension or solution of the corresponding phenol (1 equiv; 5 mmol) in DMF (20 mL), potassium carbonate was added (2 equiv; 10 mmol) followed by

• ethers from phenols and chiral non-racemic propargylic alcohols (S)-(−)-3-butyn-2-ol (5 mmol; commercially available, 464007 Sigma-Aldrich) was dissolved in THF (25 mL) in a flame dried round bottom flask, under nitrogen atmosphere, and the corresponding phenol (1.05 equiv, 5.25 mmol) and

Acid, silver, and solvent-free gold-catalyzed hydrophenoxylation of internal alkynes

• Marcia E. Richard,
• Daniel V. Fraccica,
• Kevin J. Garcia,
• Erica J. Miller,
• Rosa M. Ciccarelli,
• Erin C. Holahan,
• Victoria L. Resh,
• Aakash Shah,
• Peter M. Findeis and
• Robert A. Stockland Jr.

Beilstein J. Org. Chem. 2013, 9, 2002–2008, doi:10.3762/bjoc.9.235

• compounds have been synthesized and investigated as single-component catalysts for the hydrophenoxylation of unactivated internal alkynes. Both carbene and phosphine-ligated compounds were screened as part of this work, and the most efficient catalysts contained either JohnPhos or IPr/SIPr. Phenols bearing

• successfully functionalized. Despite the intense interest in this chemistry the addition of phenols to internal alkenes has rarely been investigated [1][5]. Recently, Sahoo reported the hydrophenoxylation of alkynes using a multicomponent catalyst comprised of AuCl3, JohnPhos as the supporting ligand, and

• gold catalyst in these reactions is proposed to occur through a protodeauration reaction between the arylgold compounds and the phenols. The observation of tert-butylbenzene in the reaction mixture supports this proposal. Furthermore, to probe whether or not simple chlorogold-coordination compounds

Gold(I)-catalysed one-pot synthesis of chromans using allylic alcohols and phenols

• Eloi Coutant,
• Paul C. Young,
• Graeme Barker and
• Ai-Lan Lee

Beilstein J. Org. Chem. 2013, 9, 1797–1806, doi:10.3762/bjoc.9.209

• Eloi Coutant Paul C. Young Graeme Barker Ai-Lan Lee Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 1LP, United Kingdom 10.3762/bjoc.9.209 Abstract A gold(I)-catalysed reaction of allylic alcohols and phenols produces chromans regioselectively via a one-pot Friedel–Crafts

• structural motifs found in a variety of important biologically active natural products such as vitamin E and flavanoids [1][2][3][4][5]. One approach towards chromans [6][7][8][9][10][11][12], which is biosynthetically inspired, is the Friedel–Crafts allylation [13] of phenols followed by cyclisation of the

• dehydrative coupling strategy) [15][16]. To this end, the use of molybdenum catalyst CpMoCl(CO)3 together with an oxidant, o-chloranil, has been documented to catalyse the reaction of allylic alcohols with phenols to form chromans [17][18]. Strong and superacids have also been utilised in the synthesis of

A Lewis acid-promoted Pinner reaction

• Dominik Pfaff,
• Gregor Nemecek and
• Joachim Podlech

Beilstein J. Org. Chem. 2013, 9, 1572–1577, doi:10.3762/bjoc.9.179

• possible. Phenols are not acylated under these reaction conditions. The method has been used for the first total synthesis of the natural product monaspilosin. In the reaction of benzyl alcohols variable amounts of amides are formed in a Ritter-type side reaction. Keywords: carbonitriles; carboxylic

• highly chemoselective; phenols were not acylated by these conditions and were re-isolated with high yields (Table 2, entries 12–14). In this context we tested 4-(2-hydroxyethyl)phenol (53) containing an aliphatic and a phenolic hydroxy function in the reaction with acetonitrile and benzyl cyanide

Practical synthesis of indoles and benzofurans in water using a heterogeneous bimetallic catalyst

• Cybille Rossy,
• Eric Fouquet and
• François-Xavier Felpin

Beilstein J. Org. Chem. 2013, 9, 1426–1431, doi:10.3762/bjoc.9.160

• with aryl acetylenes suggesting a strong halide effect and a sensitivity of the Pd–X bond under our reaction conditions. Indeed, the coupling of aryl acetylenes with bromo-anilines and bromo-phenols showed lower conversion compared to the iodo-congeners. We further evaluated the potential of our Pd–Cu

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• system was also applied to the oxygenation of 1,3,5-triisopropylbenzene [17]. However, in this case the conversion of all isopropyl groups was far from being reached, with mono- and di-phenols being the major products, while the yield in benzene-1,3,5-triol was close to 1%. Sheldon and co-workers tested

Conformational analysis and intramolecular interactions in monosubstituted phenylboranes and phenylboronic acids

• Josué M. Silla,
• Rodrigo A. Cormanich,
• Roberto Rittner and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2013, 9, 1127–1134, doi:10.3762/bjoc.9.125

• for 2-monohalogen substituted phenols [12]. In fact, organic fluorine has been found to hardly ever participate in hydrogen bonding [13], despite the appearance of this interaction in 8-fluoro-4-methyl-1-naphthol [14], 2'-fluoroflavonols [15], 2-fluorobicyclo[2.2.1]heptan-7-ols [16] and 2

A chemist and biologist talk to each other about caged neurotransmitters

• Graham C.R. Ellis-Davies

Beilstein J. Org. Chem. 2013, 9, 64–73, doi:10.3762/bjoc.9.8

• are water stable [56]. When phenols (e.g., serotonin or capsaicin) are caged via the carbonate, they are effectively stable and released quickly [61][62]. It is also important to note that the stability of all these “acid-like” caged compounds depends on the pH of the aqueous solution. All are more

Iron-containing mesoporous aluminosilicate catalyzed direct alkenylation of phenols: Facile synthesis of 1,1-diarylalkenes

• Satyajit Haldar and
• Subratanath Koner

Beilstein J. Org. Chem. 2013, 9, 49–55, doi:10.3762/bjoc.9.6

• Satyajit Haldar Subratanath Koner Department of Chemistry, Jadavpur University, Kolkata 700032, India 10.3762/bjoc.9.6 Abstract The addition of phenols to aryl-substituted alkynes to form 1,1-diarylalkenes was carried out by using the Fe-Al-MCM-41 catalyst. The catalyst showed remarkable

• improvement in time and yield in comparison to other solid catalysts. The heterogeneous catalyst can be reused at least three times without a significant loss in activity. Keywords: 1,1-diarylalkenes; heterogeneous catalysis; Fe-Al-MCM-41; Introduction The direct vinylation of phenols has received

• synthesis. Thus, the development of simple methods concerning such vinylation reactions of phenols always remains an important process. Mizoroki–Heck-type reaction could be considered as an efficient procedure for the synthesis of such vinylated phenols [18][19]. There are a number of reports available in

Reactions of salicylaldehyde and enolates or their equivalents: versatile synthetic routes to chromane derivatives

• Ishmael B. Masesane and
• Zelalem Yibralign Desta

Beilstein J. Org. Chem. 2012, 8, 2166–2175, doi:10.3762/bjoc.8.244

• [28], as catalytic reagents for silylation of alcohols, phenols, and thiols using hexamethyldisilazane [29], in conversion of urazoles to triazolinediones [30], and in oxidation of 1,3,5-trisubstituted pyrazolines [31]. Molecular sieves have been used as solid-phase catalysts in the preparation of 2