(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

• Giorgos Koutoulogenis,
• Nikolaos Kaplaneris and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2016, 12, 462–495, doi:10.3762/bjoc.12.48

• between 2-(2-nitrovinyl)phenol (208) and cyclohexanone (209, Scheme 65) [86]. When that reaction has been performed under the “regular” conditions for a Michael reaction, product 210 has been obtained in low yields. To overcome this problem, catalysts 57 and 211 were combined and the reaction goes through

Synthesis and nucleophilic aromatic substitution of 3-fluoro-5-nitro-1-(pentafluorosulfanyl)benzene

• Javier Ajenjo,
• Martin Greenhall,
• Camillo Zarantonello and
• Petr Beier

Beilstein J. Org. Chem. 2016, 12, 192–197, doi:10.3762/bjoc.12.21

• -boiling alcohols (MeOH, EtOH), the reactions were heated under reflux using the alcohol as a solvent and excess of potassium hydroxide (Table 1, entries 1 and 2). For alcohols with higher boiling points, the reactions were performed with sodium hydride (Table 1, entries 3 and 4). For phenol, thiophenol

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

• [24][25]. This transformation proceeds through the interaction of the gold centres with both the phenol and the alkyne motifs, thus generating a synergistic effect that produces unique catalytic activity (Scheme 1) [24][25]. In addition, this reaction is highly stereoselective and only the Z-isomer

• due to formation of the corresponding gem-diaurated aryl species, by reaction of catalyst [{Au(IPr)}2(µ-OH)][BF4] with the boronic ester [30], thus inhibiting the catalytic activity. The electronic properties of the phenol were also examined. If the electron density on the phenol is decreased, its

• nucleophilicity decreases and an increase in catalyst loading is needed in order to maintain relatively short reaction times (3ai and 3al) [31]. The steric hindrance on the phenol was studied next. Increasing it, with either allyl (3am) or tert-butyl (3an) groups on the ortho-position also required 1 mol % of

Diastereoselective Ugi reaction of chiral 1,3-aminoalcohols derived from an organocatalytic Mannich reaction

• Samantha Caputo,
• Andrea Basso,
• Lisa Moni,
• Renata Riva,
• Valeria Rocca and
• Luca Banfi

Beilstein J. Org. Chem. 2016, 12, 139–143, doi:10.3762/bjoc.12.15

• exploited for post-Ugi cyclization steps or as a handle for attaching further fragments: the primary alcohol and the secondary amide (which are present in all products), a protected phenol (for compounds 6c, 6i, 6j), and a protected amine (6j). Studies towards this goal are in progress and will be reported

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

• -(pentafluorosulfanyl)anisole (1) or 4-(pentafluorosulfanyl)phenol (2) by a mixture of aqueous hydrogen peroxide and concentrated sulfuric acid (Scheme 1). The major product was muconolactone 3 while maleic acid 4 and succinic acid 5 were formed in small amounts. Herein we report a full account of this oxidation

• yield of 4 might be increased when starting from 3-(pentafluorosulfanyl)anisole (10) or 3-(pentafluorosulfanyl)phenol (11). In these substrates, the first hydroxylation is likely to occur in the para position to the methoxy or hydroxy groups facilitating the formation of the para-benzoquinone derivative

• toward 4 was prepared independently (Scheme 4). Azo coupling [20] of phenol 11 with a diazonium salt prepared from sulfanilic acid afforded red azo product 13. The regioselectivity is governed by the strong para-directing hydroxy group despite the presence of the bulky SF5 group. Compounds with

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

• : cyclodextrins; DOSY-NMR; formation constant; molecular modeling; solubility; Introduction Carvacrol (2-methyl-5-(1-methylethyl)phenol, 1) and thymol (5-methyl-2-(1-methylethyl)phenol, 2) are monoterpenic phenol isomers (Figure 1) produced by several aromatic plants (oregano, thyme, savory, marjoram, etc.) [1

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

• an added incentive for this investigation [1]. We envisaged that the presence of a Michael acceptor double bond at the ortho position of a phenol would offer avenues for carbon–carbon bond forming annulation in its reaction with 2a,b. In view of their well-known reactivity profiles, diversity options

Recent highlights in biosynthesis research using stable isotopes

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

• the phenolic oxygen at C-6 to close the macrocycle in 25. In this mechanism, the aromaticity of the phenol ring remains untouched. Intramolecular Diels–Alder reaction gives rise to the hexacyclic system 26, which would then be oxidized to pyrrocidine A (24) at C-2’. In contrast to route A, the

Biocatalysis for the application of CO₂ as a chemical feedstock

• Apostolos Alissandratos and
• Christopher J. Easton

Beilstein J. Org. Chem. 2015, 11, 2370–2387, doi:10.3762/bjoc.11.259

• drive the equilibrium toward carboxylation, such as high CO2 concentration. Successful examples include the carboxylation of phenol and hydroxystyrene derivatives including catechol [102], guaiacol [110], indole [101] and pyrrole [100] (Scheme 7). Isocitrate dehydrogenase As discussed above, as part of

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

• α-bromocarbonyls. Synthesis of highly congested β-amino acids. Copper-catalyzed alkenylation reactions. Proposed mechanism of the copper-catalyzed alkenylation reaction. Scope of the copper-catalyzed alkenylation of tertiary electrophiles. Scope of the exo-methylene styrene synthesis. Phenol

• -directed synthesis of Z-alkenes. Scope of the phenol-directed Z-alkene synthesis. Rationale for the formal [3 + 2] cycloaddition. Scope of the formal [3 + 2] cycloaddition. Benzylation of styrenes using copper catalysis. Copper-catalyzed carboiodination of alkynes. Copper-catalyzed trans-carbohalogenation

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

• acetic acid at 80 °C resulted in 93% conversion and 90% selectivity towards 4-chlorophenol 20, and o-chlorinated product 21 was obtained when the para-site of the phenol was occupied; analogously, employing LiBr as halogen source led to the formation of equivalent brominated products 22 and 23 under

• process (Scheme 12). In the presence of a Cu(II) catalyst, the one-electron oxidation to the phenol led to the occurrence of phenoxy radical 25 via the formation of phenoxyl copper(II) salt 24. The isomeric free radical species 26 then rapidly captured the halogen atom from LiX to give the target product

• . CuI-mediated synthesis of iododibenzo[b,d]furans via C–H functionalization. Cu-Mn spinel oxide-catalyzed phenol and heteroarene halogenation. Copper-catalyzed halogenations of 2-amino-1,3thiazoles. Copper-mediated chlorination and bromination of indolizines. Copper-catalyzed three-component synthesis

Supramolecular chemistry: from aromatic foldamers to solution-phase supramolecular organic frameworks

• Zhan-Ting Li

Beilstein J. Org. Chem. 2015, 11, 2057–2071, doi:10.3762/bjoc.11.222

• synthesis of the 22 series, which involved the hydrolysis of the methyl ester at one end with lithium hydroxide in heated dioxane–water solution, Huiping found that the nitro-bearing anisole unit at the other end was also hydrolyzed to afford a phenol derivative [45]. In contrast, a short control did not

Total synthesis of panicein A₂

• Lili Yeung,
• Lisa I. Pilkington,
• Melissa M. Cadelis,
• Brent R. Copp and
• David Barker

Beilstein J. Org. Chem. 2015, 11, 1991–1996, doi:10.3762/bjoc.11.215

• proposed that panicein A2 (5) could be synthesised from the cyclisation and subsequent deprotection of propargyl ether 8. Ether 8 could be formed through the addition of the appropriate phenol to acetylenic alcohol 9, which itself can be derived from aldehyde 10 (Figure 3). Results and Discussion Synthesis

• ). Altering the solvent system to a 1:1 mixture of THF and diethyl ether, which also improved the solubility of the Grignard reagent, increased the yield of 9 to 95%. With alcohol 9 in hand, the next step was the key coupling of alcohol 9 and phenol 16 [11] to form the required propargyl ether 8. Godfrey et

• al. demonstrated an efficient, one-step method to synthesise propargyl ethers bearing electron withdrawing groups under mild conditions, achieved through the in situ formation of a trifluoroacetate intermediate and subsequent addition of a phenol [12], a method that has since been utilised in a

New aryloxybenzylidene ruthenium chelates – synthesis, reactivity and catalytic performance in ROMP

• Patrycja Żak,
• Szymon Rogalski,
• Mariusz Majchrzak,
• Maciej Kubicki and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2015, 11, 1910–1916, doi:10.3762/bjoc.11.206

• (Scheme 1) [11]. However, in our hands to get complete transformation 5 equiv of phosphine had to be used. In a next step the complexes (4–6) were subjected to metathesis exchange reaction with 2-(prop-1-enyl)phenol (Scheme 2). The reaction was performed in the presence of an equimolar amount of the

• 1 h when using monomer to catalyst ratio equal to 2000. Conclusion Ruthenium–benzylidene complexes bearing a triphenylphosphine ligand or its para-substituted analogues undergo metathetic exchange with 2-(prop-1-enyl)phenol or substituted 2-vinylphenols to form phenoxybenzylidene ruthenium chelates

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

• β-enol (10) [48]. Otherwise, it appears in the range δ 140.6–143.3 if C-8 bears a phenol group (compounds 3, 4, 6–8, 13, and 14) [45][46][50]. Likewise, the same downfield resonances have been found for C-6, when C-7b and its neighboring carbons C-10a or C-11a form a thiazole (see compounds 20–26

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

• Yuri A. Rulev,
• Zalina Gugkaeva,
• Victor I. Maleev,
• Michael North and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2015, 11, 1614–1623, doi:10.3762/bjoc.11.176

• . [28] 134 °C). 6,6'-((1E,1'E)-((1R,2R)-Cyclohexane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(2-(tert-butyl)-4-(dimethylamino)phenol) (7) Prepared by a modified literature procedure [30]. A solution of (1R,2R)-diaminocyclohexane (64 mg, 0.57 mmol) in ethanol (5 mL) was added dropwise to a

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• metals (such as chromium and manganese) [20][21][22]. Many SCPC oxidations of aromatics have been reported, but of these it is perhaps the oxidation of benzene to phenol that is the most industrially significant [23][24]. Unfortunately, product selectivity is poor because the phenol itself undergoes

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

• , dimers 6 and 7 are nontoxic to PC12 cells at a concentration of 40 μM and, contrary to curcumin, dimer 7 protects PC12 cells against MnCl2 damage [11]. When the phenol OH groups of dimer 8 were protected with methyl or phenyl groups, antiproliferative activity against malignant melanoma cells was

• halves are linked together in the biphenyl molecule, i.e., in ortho-position to the phenol –OH group, a steric factor of the longer side chain exerts a different influence on monomer 4 and its corresponding dimer 8. Small differences in the relative kinetic parameters for the couple dimer 7/monomer 3

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

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

• have the biggest impact on the electronic properties of the sulfonamide group due to communication through the conjugated π-system of the aromatic units and the diazene unit. Commencing with the diazotization of sulfanilamide and subsequent reaction with phenol, N,N-diethylaniline or N-phenylmorpholine

Synthesis of photoresponsive cholesterol-based azobenzene organogels: dependence on different spacer lengths

• Yuchun Ren,
• Bin Wang and
• Xiuqing Zhang

Beilstein J. Org. Chem. 2015, 11, 1089–1095, doi:10.3762/bjoc.11.122

• gel formation modes. Experimental Materials The starting materials, thylene glycol, 1,3-propanediol, 1,5-pentadiol, 1,6-hexanediol, 1,10-decanediol, 1,12-dodecanediol, cholesterol, 4-toluene sulfonyl chloride, phenol, 4-aminobenzoic acid, iodomethane, sodium nitrite, hydrochloric acid, sodium

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• and 1.77 V, in 4e and 4f (see Figure S7, Supporting Information File 1), respectively. For the phenol derivative 4f, this oxidation is irreversible. Crystal structures Compounds 4a,b,d,e afforded high quality crystals that could be analysed using X-ray crystallography, allowing to unambiguously

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

• Tommaso Pecchioli,
• Manoj Kumar Muthyala,
• Rainer Haag and
• Mathias Christmann

Beilstein J. Org. Chem. 2015, 11, 730–738, doi:10.3762/bjoc.11.83

• methyl ester hydrochloride (9). Following a protocol by Zhang and co-workers [58], 10 was obtained in good yield and subsequent anchoring of the linker was realized through O-alkylation on phenol 10, leading to linkable catalyst 5 in excellent yield (Scheme 2). The reactivity of the multivalent catalysts

Photocatalytic nucleophilic addition of alcohols to styrenes in Markovnikov and anti-Markovnikov orientation

• Martin Weiser,
• Sergej Hermann,
• Alexander Penner and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2015, 11, 568–575, doi:10.3762/bjoc.11.62

• significantly slower, since longer irradiations were needed. Only the addition of phenol failed completely. Since isopropanol and tert-butanol as sterically demanding nucleophiles gave the corresponding addition products in good yields, it was assumed that the acidity of benzyl alcohol, and more significantly

• of phenol, weakened the nucleophilicity for this type of reaction. Styrene (6) has an oxidation potential of 1.94 V (vs SCE) [22] and, hence, could also be oxidized by the chosen photocatalyst PDI. The corresponding photocatalytic nucleophilic additions to 6 (Table 1) yielded less of each product

• , which was in agreement with the higher oxidation potential (compared to 1). Here again, the addition of phenol showed no significant amounts of product formation. We representatively demonstrated the dependency of the performance of photocatalysis with substrate 1 on different PDI concentrations (Figure

Fluoride-driven ‘turn on’ ESPT in the binding with a novel benzimidazole-based sensor

• Kai Liu,
• Xiaojun Zhao,
• Qingxiang Liu,
• Jianzhong Huo,
• Bolin Zhu and
• Shihua Diao

Beilstein J. Org. Chem. 2015, 11, 563–567, doi:10.3762/bjoc.11.61

• )imino)methyl)-5-(dimethylamino)phenol (BIP) made up of benzimidazole and phenol units with a C=N linker. Although BIP is weakly fluorescent, its anion-binding adduct is expected to be highly fluorescent by opening up ESPT channel [2][14][15][19]. In this paper, we demonstrated that BIP displayed

• the phenol and benzimidazole [2][30]. Upon addition of F− (as tetrabutylammonium salts, TBA salts), as shown in Figure 1, the intensity of the band at 410 nm decreased and broadened, and a new shoulder around 466 nm formed, meanwhile, the shoulder peak at 228 nm increased. However, no noticeable

• , 271.8 mmol) containing 3-(dimethylamino)phenol (3.10 g, 22.6 mmol) at 0 °C, and the mixture was stirred for 10 min, slowly warmed to room temperature and stirred for another 30 min. The reaction mixture was heated at 80 °C overnight. After cooling to room temperature, the mixture was poured into ice