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

• exhibited the biggest difference in the antioxidant efficiency (PFd/PFm = 4) and antioxidant reactivity (IDd/IDm = 5). Recently, it has been published [20] that, theoretically, one molecule of dimer 6 is able to trap maximum nine lipid peroxide radicals, LO2, i.e., the stoichiometry of 6 is n = 9 (4.5-fold

• the fluorescence decay of fluorescein (13). In this model, there are competitive reactions of peroxide radicals between 13 and the studied compounds. The first attack in 13 is its phenolic group (see Scheme S4, Supporting Information File 1). As a monophenol without another substituents in the benzene

• qualitative correlation with models 1 and 2. The similar activity of the studied compounds acquired with the ORAC assay can be explained with the similar BDEs of 13 and of monomers and dimers. Conclusion This study compares the ability of curcumin-related compounds to scavenge different peroxide radicals and

Synthesis of γ-hydroxypropyl P-chirogenic (±)-phosphorus oxide derivatives by regioselective ring-opening of oxaphospholane 2-oxide precursors

• Iris Binyamin,
• Shoval Meidan-Shani and
• Nissan Ashkenazi

Beilstein J. Org. Chem. 2015, 11, 1332–1339, doi:10.3762/bjoc.11.143

• -tert-butyl peroxide [46]. As both methods utilize phosphorus starting materials which are not commercially available and a multistep synthesis is required for their preparation. As with oxaphospholane 4, compound 5 was reacted with 3 equiv of various Grignard reagents to produce phosphine oxides in

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

The chemical behavior of terminally tert-butylated polyolefins

• Dagmar Klein,
• Henning Hopf,
• Peter G. Jones,
• Ina Dix and
• Ralf Hänel

Beilstein J. Org. Chem. 2015, 11, 1246–1258, doi:10.3762/bjoc.11.139

• . Exploratory photochemical studies were carried out with tetraene 19 as the model compound. On irradiation this reacted with oxygen to the stable endo-peroxide 52. Keywords: bromination; Diels–Alder reactions; epoxidation; photochemistry; polyolefins; reactivity; hydrogenation; Introduction Several years ago

• deuteriochloroform solution in the presence of air, endo-peroxide 52 was isolated in 46% yield. Its structure follows from its spectroscopic data (see Supporting Information File 1) and, in particular, an X-ray structural investigation of single crystals obtained from a petrol ether solution. The molecule of 52 is

New palladium–oxazoline complexes: Synthesis and evaluation of the optical properties and the catalytic power during the oxidation of textile dyes

• Rym Hassani,
• Mahjoub Jabli,
• Yakdhane Kacem,
• Jérôme Marrot,
• Damien Prim and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2015, 11, 1175–1186, doi:10.3762/bjoc.11.132

• experimental results indicated that the complexes have potential activities during the degradation of the azo dyes in the aqueous medium and in the presence of hydrogen peroxide. From the preliminary data, it was found that all the prepared complexes have demonstrated a promising catalytic activity at the same

• ) [33][34]. Effect of the hydrogen peroxide concentration As proved in the previous section, the action of H2O2 alone did not show any degradation capacity for the studied dye solution, although this agent is considered a relatively powerful oxidant. In this section, we examine the effect of H2O2 dose

• target removal of Eriochrome Blue Black B was reached within minutes, under some experimental conditions. These new complexes prove to be active and also to be a reusable catalyst for the decolorization of Erio solutions in the presence of hydrogen peroxide. Further work is ongoing to apply the same

Properties of PTFE tape as a semipermeable membrane in fluorous reactions

• Brendon A. Parsons,
• Olivia Lin Smith,
• Myeong Chae and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2015, 11, 980–993, doi:10.3762/bjoc.11.110

• chemiluminescence experiment as a qualitative test. The known chemiluminescence reaction of the diaryl oxalate esters oxidized by hydrogen peroxide in the presence of rubrene was investigated (Scheme 2) [38][39][40]. Two solutions were prepared. One solution contained a mixture of diaryl oxalate and rubrene in

• dimethyl phthalate. The second solution was hydrogen peroxide dissolved in either water, or a water–organic solvent mixture. The solutions in the vial and delivery tube were alternated to ensure that the direction of diffusion was not gravity or density-dependent. We observed that the chemiluminescence

• reaction was directional. Only the oxalate–rubrene solution exhibited luminescence during the reaction, regardless of whether it was in the delivery tube or the vial (Figure 11). The peroxide solution remained dark. The reactions with the aqueous peroxide solution proceeded with no change in the column

Eosin Y-catalyzed visible-light-mediated aerobic oxidative cyclization of N,N-dimethylanilines with maleimides

• Zhongwei Liang,
• Song Xu,
• Wenyan Tian and
• Ronghua Zhang

Beilstein J. Org. Chem. 2015, 11, 425–430, doi:10.3762/bjoc.11.48

• derivatives under organic dye Eosin Y catalysis. Swan and Roy reported the reaction using benzoyl peroxide as catalyst at low temperature as early as 1968 [42]. In 2011, Miura and co-workers achieved this transformation using a copper catalyst and air as the terminal oxidant [43]. Bian and co-workers

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2015, 11, 392–402, doi:10.3762/bjoc.11.45

• numeral, but the acetylated derivative is amended by the letter “a”, e.g., cholesterol (1) and cholesteryl acetate (1a). Indirect electrochemical oxidation of cholesterol The selective oxidation of saturated hydrocarbons by dioxygen and hydrogen peroxide remains a challenging problem in chemistry and

• cholesterol took place in the cathodic compartment. The oxidation did not occur without the electrochemical reduction of Tl(III), which suggests that Tl(III) cannot activate dioxygen. In addition, the replacement of dioxygen by hydrogen peroxide gave a mixture of oxidation products. This indicates that

• dioxygen was not electrochemically reduced to hydrogen peroxide, which could act as an oxidant. It was also observed that the replacement of Tl(III) with Fe(III) caused a decrease in the reaction yield and the replacement of HMP with tetraphenylporphyrin or its derivatives resulted in product mixtures

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

• were obtained when 3-phenyl-2-(phenylsulfonyl)oxaziridine (14) was employed, but product 15 from the concomitant reaction of bisenolate addition to N-sulfonimine byproduct was also isolated in 15% yield from this reaction. Some peroxide-based electrophilic oxidants (Table 1, entries 3–5) were also

Synthesis of the furo[2,3-b]chromene ring system of hyperaspindols A and B

• Danielle L. Paterson and
• David Barker

Beilstein J. Org. Chem. 2015, 11, 265–270, doi:10.3762/bjoc.11.29

• antibacterial and antiviral activities, as well as inhibitory activity on thromboxane A2 and leukotriene D4 [4]. Acylphloroglucinols are known to act as anti-oxidants, by reducing hydroperoxides and hydrogen peroxide, thereby suppressing the formation of the reactive species [9]. The hyperaspidinols 1 and 2

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

• solvent mixture at 100–110 °C for 18 h. The oxazole moiety also acts as the directing group in the acetoxylation of alkyl groups with Pd(OAc)2/AcOOt-Bu or Pd(OAc)2/lauroyl peroxide oxidative systems; in these reactions acetic anhydride served as the source of the acetoxy groups [88]. Recently, Cu(OAc)2

• -BuOOH in the presence of Bu4NI [143]. It is proposed that tert-butyl peresters 144 are produced as a result of the recombination of acyl radicals 145 and tert-butyl peroxide radicals. The radical reaction mechanism was confirmed by the experiment, in which acyl radicals generated from aldehyde 146 were

• or their hetero analogues, as well as for the generation of tert-butyl peroxide radicals, which react with this complex to give coupling products 214 (Scheme 44). The related peroxidation reactions with hydroperoxides (t-BuOOH, PhMe2COOH) in the presence of transition metal salts (cobalt, manganese

One-pot functionalisation of N-substituted tetrahydroisoquinolines by photooxidation and tunable organometallic trapping of iminium intermediates

• Joshua P. Barham,
• Matthew P. John and
• John A. Murphy

Beilstein J. Org. Chem. 2014, 10, 2981–2988, doi:10.3762/bjoc.10.316

• used, allylindium reagents generated and indium trihalide salt byproducts are non-toxic [43]. Our conditions benefit from the absence of amide side-products typically effected by peroxide intermediates in aerobic photoactivation of THIQs [16][22] and so our methodology serves to complement existing

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• subsequently the intermediate underwent intramolecular cyclization and oxidative aromatization to form the phenanthridine ring. Bowman et al. [16] modified this route for safety reasons by application of di(tert-butyl)peroxide as a source of the t-BuO• radical (Scheme 3). The required arylimines were prepared

• from aminobiphenyl and arylaldehyde in dichloromethane in the presence of molecular sieves at room temperature. Radical cyclisation in the presence of (tert-butyl)peroxide in chlorobenzene at 140–150 °C for 48 h, yielded the corresponding phenanthridines in moderate yields. The t-BuO• radical

Preparation of neuroprotective condensed 1,4-benzoxazepines by regio- and diastereoselective domino Knoevenagel–[1,5]-hydride shift cyclization reaction

• László Tóth,
• Yan Fu,
• Hai Yan Zhang,
• Attila Mándi,
• Katalin E. Kövér,
• Tünde-Zita Illyés,
• Attila Kiss-Szikszai,
• Balázs Balogh,
• Tibor Kurtán,
• Sándor Antus and
• Péter Mátyus

Beilstein J. Org. Chem. 2014, 10, 2594–2602, doi:10.3762/bjoc.10.272

• . Separated enantiomers of the products were characterized by HPLC-ECD data, which allowed their configurational assignment on the basis of TDDFT-ECD calculation of the solution conformers. Two compounds showed neuroprotective activities against hydrogen peroxide (H2O2) or β-amyloid25–35 (Aβ25–35)-induced

• preparation of condensed O,N-heterocycles with the 1,2,8,9-tetrahydro-7bH-quinolino[1,2-d][1,4]benzoxazepine skeleton, the neuroprotective activities of which were tested against hydrogen peroxide (H2O2), Alzheimer's amyloid β-peptide fragment Aβ25–35 and oxygen–glucose deprivation (OGD)-induced neurotoxicity

• rac-5 were tested against hydrogen peroxide (H2O2), β-amyloid-25-35 (Aβ25–35) and oxygen–glucose deprivation (OGD)-induced neurotoxicity in human neuroblastoma SH-SY5Y cells [22]. The preliminary screenings showed that rac-7a at 10 µM concentration displayed neuroprotective activity against H2O2

Oligomerization of optically active N-(4-hydroxyphenyl)mandelamide in the presence of β-cyclodextrin and the minor role of chirality

• Helmut Ritter,
• Antonia Stöhr and
• Philippe Favresse

Beilstein J. Org. Chem. 2014, 10, 2361–2366, doi:10.3762/bjoc.10.246

• of both enantiomers of N-(4-hydroxyphenyl)mandelamide (1) were obtained though oxidative coupling with peroxidase and laccase and also via oligomerization with iron(II)-salen and hydrogen peroxide as a catalyzing system. In the presence of RAMEB-CD it was possible to oligomerize the poorly water

• oligo (N-(4-hydroxyphenyl)mandelamide) (2) Enzymatic oxidative oligomerization with peroxidase: A solution of 7.5 mg peroxidase dissolved in 10 ml pH 7 buffer was added to a solution of 1.22 g (5 mmol) N-(4-hydroxyphenyl)mandelamide (1) and 40 mL 1.4-dioxan. 510 µL of hydrogen peroxide (30%) were added

• reaction mixture. After addition of 510 µL of hydrogen peroxide (30%) in aliquots of 51 µL in 15 minutes intervals, the mixture was stirred for 2 h at room temperature. The precipitated product was isolated by filtration, washed with 0.5 M HCl, water and dried. Then the oligomer was dissolved in dioxan

Efficient routes toward the synthesis of the D-rhamno-trisaccharide related to the A-band polysaccharide of Pseudomonas aeruginosa

• Aritra Chaudhury,
• Sajal K. Maity and
• Rina Ghosh

Beilstein J. Org. Chem. 2014, 10, 1488–1494, doi:10.3762/bjoc.10.153

• by the selective cleavage of the same with 80% aq AcOH. Compound 3a which is the phenyl thioglycoside analogue of 4 was also accessed similarly. Both the compounds were next converted to their rhamnoside counterparts 6 and 7 [44], respectively by treatment with di-tert-butyl peroxide (DTBP) and

Cyclization–endoperoxidation cascade reactions of dienes mediated by a pyrylium photoredox catalyst

• Nathan J. Gesmundo and
• David A. Nicewicz

Beilstein J. Org. Chem. 2014, 10, 1272–1281, doi:10.3762/bjoc.10.128

• to 79%. Keywords: alkene; cascade; endoperoxide; oxidation; photoredox catalysis; Introduction Endoperoxides are a structurally unique class of naturally-occurring compounds that feature a reactive cyclic peroxide moiety of varying ring sizes (Figure 1). The lability of the endocyclic peroxide O–O

• its susceptibility to reduction and for this reason, is ideally introduced late-stage in target-oriented synthesis. Additionally, many endoperoxide natural products possess architecturally complex frameworks (e.g., artemisinin, yingzhaosu A, muurolan-4,7-peroxide) [5] that pose significant synthetic

• reactions of peroxyquinols [11]. While these extant methods are effective at installing the endoperoxide functional group, our interest lay in developing strategies that simultaneously forged both the cyclic peroxide as well as the carbon framework to rapidly build molecular complexity. For this reason, we

Magnesium bis(monoperoxyphthalate) hexahydrate as mild and efficient oxidant for the synthesis of selenones

• Andrea Temperini,
• Massimo Curini,
• Ornelio Rosati and
• Lucio Minuti

Beilstein J. Org. Chem. 2014, 10, 1267–1271, doi:10.3762/bjoc.10.127

• efficient and mild methods for their synthesis is of considerable interest. A few previous papers report the synthesis of selenones 2 by oxidation of the corresponding selenides 1 with potassium permanganate [4], trifluoroacetic acid [4] and hydrogen peroxide in trifluoroethanol with stoichiometric amounts

Synthesis of ethoxy dibenzooxaphosphorin oxides through palladium-catalyzed C(sp²)–H activation/C–O formation

• Seohyun Shin,
• Dongjin Kang,
• Woo Hyung Jeon and
• Phil Ho Lee

Beilstein J. Org. Chem. 2014, 10, 1220–1227, doi:10.3762/bjoc.10.120

• )arylphosphonates by using L-Selectride (Scheme 2). The C–H activation/C–O formation of 2-(phenyl)phenylphosphonic acid monoethyl ester (1a) was examined with a variety of oxidants and bases in the presence of Pd(OAc)2. A multitude of oxidants such as K2S2O8, BQ, benzoyl peroxide, PhI(TFA)2, Cu(OAc)2, CuCl2, CuBr

Nonanebis(peroxoic acid): a stable peracid for oxidative bromination of aminoanthracene-9,10-dione

• Vilas Venunath Patil and
• Ganapati Subray Shankarling

Beilstein J. Org. Chem. 2014, 10, 921–928, doi:10.3762/bjoc.10.90

• at the expense of 1.25 equivalents of peroxide in 2 h (Table 2, entry 15). No product formation was observed in the absence of peracid (Table 2, entry 16). To confirm the efficiency of nonanebis(peroxoic acid), bromination was carried out using commercially available oxidants. The results obtained

• , Oxone (Table 3, entry 2) shows 94% conversion of 1a in 2 h. In case of 50% Hydrogen peroxide (Table 3, entry 3), more than 7 equivalents of oxidant were required with successive addition. The urea hydrogen peroxide shows moderate conversion in 20 h (Table 3, entry 6). The other diperoxy acids like

• was surmised that in the presence of oxidant these substrates form a diimine type product (similar to oxidative hair dye mechanism) [33], which makes the ring unreactive towards electrophilic substitution. Since Oxone and 50% hydrogen peroxide showed good results with substrate 1a, we have checked the

End-group-functionalized poly(N,N-diethylacrylamide) via free-radical chain transfer polymerization: Influence of sulfur oxidation and cyclodextrin on self-organization and cloud points in water

• Sebastian Reinelt,
• Daniel Steinke and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 680–691, doi:10.3762/bjoc.10.61

• accomplished by oxidation with hydrogen peroxide in analogy to literature [11]. As expected, the MALDI–TOF mass spectrum for 8bOx showed only one series of peaks, which was shifted by 16 Dalton in comparison to the origin series of peaks (see Figure 3). The FTIR spectrum showed a decrease of transmission at a

Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

• Ludovic Eberlin,
• Fabien Tripoteau,
• François Carreaux,
• Andrew Whiting and
• Bertrand Carboni

Beilstein J. Org. Chem. 2014, 10, 237–250, doi:10.3762/bjoc.10.19

• diastereomers (Scheme 25). No formation of products resulting from a first cycloaddition of the 1,3-butadienyl moiety was observed when these reactions were conducted in a tandem one-pot process. Various transformations were further carried out as oxidation with hydrogen peroxide or addition to aldehydes that

Synthesis and biological activity of N-substituted-tetrahydro-γ-carbolines containing peptide residues

• Nadezhda V. Sokolova,
• Valentine G. Nenajdenko,
• Vladimir B. Sokolov,
• Daria V. Vinogradova,
• Elena F. Shevtsova,
• Ludmila G. Dubova and
• Sergey O. Bachurin

Beilstein J. Org. Chem. 2014, 10, 155–162, doi:10.3762/bjoc.10.13

• ] (Figure 1). These peptides were found to scavenge hydrogen peroxide and peroxynitrite and inhibit lipid peroxidation in vitro. By reducing mitochondrial reactive oxygen species, they inhibit MPT and cytochrome c release, thus protecting cells from oxidative cell death [11]. We expected that the

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

• fundamental organic reactions. Due to these properties, the molecular structures can be greatly modified to give peroxide ring-retaining products. The chemistry of cyclic peroxides has attracted considerable attention, because these compounds are used in medicine for the design of antimalarial, antihelminthic

• peroxides are based on three key reagents: oxygen, ozone, and hydrogen peroxide. These reagents and their derivatives are used in the main methods for the introduction of the peroxide group, such as the singlet-oxygen ene reaction with alkenes, the [4 + 2]-cycloaddition of singlet oxygen to dienes, the

• Mukaiyama–Isayama peroxysilylation of unsaturated compounds, the Kobayashi cyclization, the nucleophilic addition of hydrogen peroxide to carbonyl compounds, the ozonolysis, and reactions with the involvement of peroxycarbenium ions. Each part of the review deals with a particular class of the above

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• functionalized in moderate yields by using sodium trifluoromethanesulfinate (Langlois’s reagent) and tert-butyl peroxide with 10 mol % of copper(II) triflate (Table 19). The supposed mechanism implies single electron transfers where t-BuOOH and Cu(OTf)2 serve as oxidants (Figure 9). Interestingly, Langlois’s

• benzoyl peroxide (Scheme 8). The copper salts are believed to speed up the process by superimposing a redox chain to the radical chain [90]. 3.2.4 Trifluoromethylation of Csp2–H bonds by means of a nucleophilic CF3-source. To the best of our knowledge, there is only one report in the literature by L. Chu

• ]thiazoles, imidazoles and polyfluorobenzenes (same system but di-tert-butyl peroxide as oxidant instead of air, Table 21); the nature of the copper(II) salt, the base and the oxidant had to be reassessed for the reaction of indoles (Cu(OH)2/1,10-phenanthroline/KF/Ag2CO3). Interestingly, the results obtained