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

• consumption of hydrogen peroxide. It has been shown that the AS is substrate tolerant and accepts different hydroxylation patterns as well as glycosylations on the chalcone A and B rings [154]. However, the oxidative half-reaction only occurs with chalcones and not with other aryl substrates like L-tyrosine

Automated glycan assembly of a S. pneumoniae serotype 3 CPS antigen

• Markus W. Weishaupt,
• Stefan Matthies,
• Mattan Hurevich,
• Claney L. Pereira,
• Heung Sik Hahm and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2016, 12, 1440–1446, doi:10.3762/bjoc.12.139

• using a mixture of lithium hydroxide and hydrogen peroxide to avoid elimination reactions which are common for uronic acid methyl esters under strongly basic conditions [30][32]. In the next step, the remaining esters were removed employing sodium hydroxide in methanol. Finally, catalytic hydrogenation

Interactions between 4-thiothymidine and water-soluble cyclodextrins: Evidence for supramolecular structures in aqueous solutions

• Vito Rizzi,
• Sergio Matera,
• Paola Semeraro,
• Paola Fini and
• Pinalysa Cosma

Beilstein J. Org. Chem. 2016, 12, 549–563, doi:10.3762/bjoc.12.54

• , ROS (namely singlet oxygen, superoxide ions and hydrogen peroxide), generated via the excited state of the PS, destroy the PS itself. Because of this, the effort to preserve the PS is one of main issues. Regarding S4TdR, as a result of its photodynamic activity, the thiobase can be destroyed by a

Aluminacyclopentanes in the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes

• Vladimir A. D’yakonov,
• Alevtina L. Makhamatkhanova,
• Rina A. Agliullina,
• Leisan K. Dilmukhametova,
• Tat’yana V. Tyumkina and
• Usein M. Dzhemilev

Beilstein J. Org. Chem. 2016, 12, 406–412, doi:10.3762/bjoc.12.43

• dichlorophosphines (R′PCl2). Hydrogen peroxide oxidation and treatment with S8 of the synthesized phospholanes and α,ω-bisphospholanes afforded the corresponding 3-alkyl(aryl)-1-alkyl(phenyl)phospholane 1-oxides, 3-alkyl(aryl)-1-alkyl(phenyl)phospholane 1-sulfides, bisphospholane 1,1'-dioxides, and bisphospholane

• regioisomers react in situ with phosphorus dihalides and hydrogen peroxide to afford 1-phenyl(alkyl)-2-arylphospholane oxides 7a–f and 1-phenyl(alkyl)-3-arylphospholane oxides 8a–f in 2:1 ratio in a 69–87% total yield (Table 2). The regioisomers were isolated by column chromatography (hexane/ethyl acetate

• ]+): 277.4046; found: 277.4. Preparation of 3-alkyl(aryl)phospholane-1-oxides (general procedure) A 30% solution of hydrogen peroxide (0.7 mL, 6 mmol) was slowly added dropwise with vigorous stirring to a solution of 3-alkyl(benzyl)-1-alkyl(phenyl)phospholane (5 mmol), synthesized as described above, in

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

• -(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

• )anisole and 4-(pentafluorosulfanyl)phenol the meta-derivatives 10 and 11 underwent oxidation with aqueous hydrogen peroxide in sulfuric acid to provide SF5-muconolactone and SF5-maleic acid as main products. Improved conversion of SF5-maleic acid was rationalized by preferential formation of SF5

Supramolecular polymer assembly in aqueous solution arising from cyclodextrin host–guest complexation

• Jie Wang,
• Zhiqiang Qiu,
• Yiming Wang,
• Li Li,
• Xuhong Guo,
• Duc-Truc Pham,
• Stephen F. Lincoln and
• Robert K. Prud’homme

Beilstein J. Org. Chem. 2016, 12, 50–72, doi:10.3762/bjoc.12.7

• greatly deceased upon the addition of β-CD because host–guest complexation of ferrocene masks its hydrophobicity and the hydrophilic exterior of the complexing β-CD much decreases association between the polymer chains. The same effect occurs when hydrogen peroxide is added to aqueous BPEI-FC and the

Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

• David Porter,
• Belinda M.-L. Poon and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2015, 11, 2549–2556, doi:10.3762/bjoc.11.275

• 5. Nicholas and Kalita have reported that the addition of hydrogen peroxide can improve yields in their copper-catalysed allylic amination reactions using BocNHOH [41]. Thus the addition of hydrogen peroxide (1:1 relative to BocNHOH) to reactions with 4 or 5 was investigated. Using a 1:1:1 ratio of

• cyclohexene:BocNHOH:H2O2 with FeTPA (4) at 1 mol %, allylic hydroxylamine 9 was formed in only 4% yield, with the allylic oxidation products 9 and 10 predominant. This is not unexpected given the propensity of hydrogen peroxide to react directly with iron complexes to produce 10 and 11 via Fenton-type pathways [47][53

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

• donor and ‘picks up’ holes thereby releasing a cascade of extremely reactive hydroxyl radicals (see Figure 2). Oxygen acts as the acceptor, picks up electrons from the semiconductor surface, so yielding superoxide anions that are converted to hydroperoxyl radicals and to hydrogen peroxide on successive

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

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

• in solvent volume in the delivery tube, we conclude that PTFE tape is permeable to small H2O2 molecules but not to the considerably larger oxalate or rubrene molecules. In the reactions where hydrogen peroxide was dissolved in acetonitrile/water (2:1) or tert-butanol/water (2:1) mixtures, the column

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

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

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

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

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

• , 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

• 50–55 °C. The N-alkylated substrates such as 1i, 1j and the substrate 1k showed poor conversion (product formed in tracess) even at a higher temperature when 50% hydrogen peroxide was used as an oxidant. This study demonstrates the superiority of nonanebis(peroxoic acid) under the present protocol

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

• 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

• peroxide moiety, the Isayama–Mukaiyama peroxysilylation, and reactions involving peroxycarbenium ions. Syntheses employing hydrogen peroxide and the intramolecular Kobayashi cyclization are less frequently used. 1.1. Use of oxygen for the peroxide ring formation The singlet-oxygen ene reaction with alkenes

Biosynthesis of rare hexoses using microorganisms and related enzymes

• Zijie Li,
• Yahui Gao,
• Hideki Nakanishi,
• Xiaodong Gao and
• Li Cai

Beilstein J. Org. Chem. 2013, 9, 2434–2445, doi:10.3762/bjoc.9.281

• sanctum seeds) and investigated their synthetic application for L-glucose production from D-sorbitol (Scheme 13) [83][84]. Catalase could degrade the hydrogen peroxide byproduct and increase the conversion by removing the inhibition effect of hydrogen peroxide toward galactose oxidase and regenerating

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• -step sequence yielded azetidine 107. After oxidation with hydrogen peroxide, the resulting N-oxide cleanly underwent a [1,2]-Meisenheimer rearrangement upon heating in tetrahydrofuran. The so-formed azocine 108 was converted to amine 109 by hydrogenolysis of the N–O bond. Amide formation with acid

Integrating reaction and analysis: investigation of higher-order reactions by cryogenic trapping

• Skrollan Stockinger and
• Oliver Trapp

Beilstein J. Org. Chem. 2013, 9, 1837–1842, doi:10.3762/bjoc.9.214

• reactions, so that the reaction kinetics can be investigated under comparable reaction conditions. So far, we investigated only first-order or pseudo-first-order reactions, where, for example, one reactant is used as a carrier gas, i.e., hydrogen in hydrogenation reactions or hydrogen peroxide as oxidant