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

• to alkyl-containing ketones to give the target products in yields of 30–91% and good regioselectivity 7:1 to 20:1 (Scheme 28) [261]. Asymmetric oxidation: Asymmetric Baeyer–Villiger oxidation reactions can be performed using chiral acetals, organic hydroperoxides, chiral metal complexes and

Biosynthesis of α-pyrones

• Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

• , for most of them the clarification of the biosynthesis remained unknown for many years. An early example for a biosynthetic hypothesis is the biosynthesis of the simple 6-pentyl-α-pyrone (29), which was hypothesized to start with the C-18 linoleic acid. This acid is then shortened by β-oxidation

• reactions to a C-10 intermediate, i.e., 5-hydroxy-2,4-decenoic acid (72), which undergoes lactonization to yield 29 (Figure 17) [34]. This hypothesis is based on the fact that feeding studies with Trichoderma harzianum and T. viride using [U-14C]linoleic acid or [5-14C]sodium mevalonate revealed 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

• reaction volume of 1 mL). Under these conditions the yield of allylic amine 9 doubled relative to the more dilute 1:1 reaction, to 17%; 10 and 11 were not observed. Reaction using a chiral catalyst The chiral catalyst Fe(R,R′)-PDP (6) has been used previously to promote asymmetric C–H oxidation reactions

Active site diversification of P450cam with indole generates catalysts for benzylic oxidation reactions

• Paul P. Kelly,
• Anja Eichler,
• Susanne Herter,
• David C. Kranz,
• Nicholas J. Turner and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2015, 11, 1713–1720, doi:10.3762/bjoc.11.186

Chiroptical properties of 1,3-diphenylallene-anchored tetrathiafulvalene and its polymer synthesis

• Masashi Hasegawa,
• Junta Endo,
• Seiya Iwata,
• Toshiaki Shimasaki and
• Yasuhiro Mazaki

Beilstein J. Org. Chem. 2015, 11, 972–979, doi:10.3762/bjoc.11.109

• cationic species of TTF in any cationic species derived from 3 or PTDPA. Only small changes of λfirst and λsecond peaks, mainly associated with the 1,3-diphenylallene framework, were observed during the oxidation reactions. In the present chiral system, the chiroptical effects between two TTF units are

Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

• Grzegorz Mlostoń,
• Paulina Grzelak,
• Maciej Mikina,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2015, 11, 576–582, doi:10.3762/bjoc.11.63

• the present study were used for oxidation reactions aimed at the preparation of the corresponding sulfoxides and sulfones. As demonstrated in a recent publication [20], polycyclic sulfones are attractive substrates for the synthesis of polycyclic hydrocarbons via thermal SO2 extrusion. In our

• ). The course of the oxidation reactions for these thiopyrans differs from a similar process reported for Se-containing systems. In these cases, ring contraction and elimination of an aryl group, but no formation of an oxidized product, was observed [21]. The same report describes the appearance of

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

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

• toxic products. These are formed due to oxidation reactions caused by the contact with oxygen, the exposure to sunlight, heating treatments, etc. [5][6][7]. Furthermore, they can be generated in the human organism through different oxidation processes, some of which require enzymes. Cholesterol

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

• the reaction was essentially complete in 20 minutes according to TLC analysis. Oxidation reactions performed in polar aprotic solvents, such as DMPU and DMF, gave significantly lower yields compared to THF. As with the parent tetramic acids, isolation and purification of the hydroxylated derivatives

Photovoltaic-driven organic electrosynthesis and efforts toward more sustainable oxidation reactions

• Bichlien H. Nguyen,
• Robert J. Perkins,
• Jake A. Smith and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2015, 11, 280–287, doi:10.3762/bjoc.11.32

• conducting a wide variety of sustainable oxidation reactions. The approach presented in this article is compatible with both direct and indirect oxidation reactions, avoids the need for a stoichiometric oxidant, and leads to hydrogen gas as the only byproduct from the corresponding reduction reaction

• . Keywords: electrochemistry; sustainable oxidation reactions; visible light; Introduction Organic electrochemistry is an extremely versatile tool for conducting a wide variety of chemical reactions [1][2][3]. This versatility stems from both the gentle, acid/base neutral reaction conditions employed for

• cathode. For all of the oxidation reactions highlighted in this work, this reduction reaction leads to the formation of hydrogen gas. In addition to the direct oxidation of a substrate described in the preceding paragraph, indirect electrochemical methods also offer a powerful means of recycling chemical

Cathodic reductive coupling of methyl cinnamate on boron-doped diamond electrodes and synthesis of new neolignan-type products

• Taiki Kojima,
• Rika Obata,
• Tsuyoshi Saito,
• Yasuaki Einaga and
• Shigeru Nishiyama

Beilstein J. Org. Chem. 2015, 11, 200–203, doi:10.3762/bjoc.11.21

• window against evolution of both hydrogen and oxygen and for their high stability which is derived from their diamond carbon structure [6]. Although anodic oxidation reactions mediated by BDD electrodes have been exploited in organic synthesis, there have been only few reports regarding their application

• in preparative-scale cathodic reduction of organic compounds [7]. During our investigations of phenolic oxidation reactions using BDD electrodes, we observed the generation of solvent-derived methoxy radicals that conducted an oxidation process of the phenol substrate to the corresponding coupling

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• introduction of the nucleophile to the C–X bond that contains the electroauxiliary (Scheme 4). Similarly, α-silyl-carbamates undergo low potential anodic oxidation reactions with complete regiocontrol and in special cases diastereoselectivity [34][35]. Interestingly, a porous graphite felt anode and a

An integrated photocatalytic/enzymatic system for the reduction of CO₂ to methanol in bioglycerol–water

• Michele Aresta,
• Angela Dibenedetto,
• Tomasz Baran,
• Antonella Angelini,
• Przemysław Łabuz and
• Wojciech Macyk

Beilstein J. Org. Chem. 2014, 10, 2556–2565, doi:10.3762/bjoc.10.267

• from NAD+ would be of great interest due to their low cost, moderate (ambient) operational conditions and acceptable environmental impact. The most extensively applied photochemical processes are based on the use of TiO2 as a photocatalyst in oxidation reactions [14][15][16]. While pure TiO2 has a band

Oxidative phenylamination of 5-substituted 1-hydroxynaphthalenes to N-phenyl-1,4-naphthoquinone monoimines by air and light “on water”

• Julio Benites,
• Juan Meléndez,
• Cynthia Estela,
• David Ríos,
• Luis Espinoza,
• Iván Brito and
• Jaime A. Valderrama

Beilstein J. Org. Chem. 2014, 10, 2448–2452, doi:10.3762/bjoc.10.255

• concluded that the oxidative arylamination of 1,5-DHN (1) is favorable with arylamines containing electron-donor substituents. Bearing in mind that the formation of the quinone monoimines 6–10 under the above experimental conditions requires aerial oxidation reactions, most likely mediated by oxygen species

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

• Sanjeewa N. Senadheera,
• Abraham L. Yousef and
• Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

• deconjugative rearrangement, instead follow a homolytic pathway. This results in lower yields, poorer efficiencies, and incomplete conversion for 2,6-HNA, and intractable mixtures of chromophoric byproducts and secondary oxidation reactions with O2, for 5,8-BQA. Neither chromophore is suitable for application

Site-selective covalent functionalization at interior carbon atoms and on the rim of circumtrindene, a C₃₆H₁₂ open geodesic polyarene

• Hee Yeon Cho,
• Ronald B. M. Ansems and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2014, 10, 956–968, doi:10.3762/bjoc.10.94

• used to functionalize the existing polyarenes and/or to extend them to larger PAHs. The most common class of reactions is the electrophilic aromatic substitution; however, free radical, nucleophilic addition, reduction, and oxidation reactions are also possible. To synthesize larger PAHs that are not

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

Copper(II)-salt-promoted oxidative ring-opening reactions of bicyclic cyclopropanol derivatives via radical pathways

• Eietsu Hasegawa,
• Minami Tateyama,
• Ryosuke Nagumo,
• Eiji Tayama and
• Hajime Iwamoto

Beilstein J. Org. Chem. 2013, 9, 1397–1406, doi:10.3762/bjoc.9.156

• mixture of 1b and 5 (12:88). Therefore, 5 may not result from the copper(II)-oxidation reaction. Based on the above observations, we anticipated that sterically less hindered cyclopropanols would more efficiently undergo copper(II)-induced oxidation reactions than the corresponding silyl ethers. To probe

Copper-catalyzed aerobic aliphatic C–H oxygenation with hydroperoxides

• Pei Chui Too,
• Ya Lin Tnay and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2013, 9, 1217–1225, doi:10.3762/bjoc.9.138

• tertiary C–H bonds, respectively (Scheme 1b) [8][9]. Stimulated by these remote sp3 C–H oxidation reactions using the nitrogen-centered radicals derived from amidines and ketimines, we became interested to utilize oxygen-centered radicals (O-radicals) for the sp3 C–H functionalization. In this context, we

Selective copper(II) acetate and potassium iodide catalyzed oxidation of aminals to dihydroquinazoline and quinazolinone alkaloids

• Matthew T. Richers,
• Chenfei Zhao and
• Daniel Seidel

Beilstein J. Org. Chem. 2013, 9, 1194–1201, doi:10.3762/bjoc.9.135

• aminals. Here we present catalytic methods for the synthesis of both these compound classes from aminals using Cu(OAc)2/O2/AcOH and KI/TBHP systems, respectively. Results and Discussion Copper-catalyzed oxidations of aminals to dihydroquinazolines Copper-catalyzed oxidation reactions have received a great

NHC-catalysed highly selective aerobic oxidation of nonactivated aldehydes

• Lennart Möhlmann,
• Stefan Ludwig and
• Siegfried Blechert

Beilstein J. Org. Chem. 2013, 9, 602–607, doi:10.3762/bjoc.9.65

• NHC catalyst in hand, we tried oxidation reactions of cyclohexanecarbaldehyde as a nonactivated substrate. During these studies we observed a catalytic oxidation with oxygen using 20 mg mpg-C3N4 per millimol of aldehyde, even without light. Following the reaction by GC-analysis showed an exponential

Polar reactions of acyclic conjugated bisallenes

• Reiner Stamm and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 36–48, doi:10.3762/bjoc.9.5

• is known about the behavior of noncyclic, conjugated bisallenes in ionic or polar reactions, whether these involve metalation processes, the addition of halogens and hydrogen halides, or oxidation reactions, to name but a few. To fill this gap we initiated a research program, hoping also that polar

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Chemo-enzymatic modification of poly-N-acetyllactosamine (LacNAc) oligomers and N,N-diacetyllactosamine (LacDiNAc) based on galactose oxidase treatment

• Christiane E. Kupper,
• Ruben R. Rosencrantz,
• Birgit Henßen,
• Helena Pelantová,
• Stephan Thönes,
• Anna Drozdová,
• Vladimir Křen and
• Lothar Elling

Beilstein J. Org. Chem. 2012, 8, 712–725, doi:10.3762/bjoc.8.80

• . Enzyme activity was determined from the linear reaction rate. Oxidation of 1a–d and 2 Standard oxidation reactions were performed in oxygen-saturated sodium phosphate buffer (50 mM, pH 6, saturated by flushing pure oxygen into the buffer for 10 min). Open glass vessels were used to allow easy oxygen

• scale, variations of the standard procedure were assessed, for example, different pH values, enzyme amounts or reaction time. For the analysis of oxidation reactions, reversed-phase HPLC utilizing method C was performed. Qualitative fast monitoring of the reaction progress was also done by TLC

Synthesis and oxidation of some azole-containing thioethers

• Andrei S. Potapov,
• Nina P. Chernova,
• Vladimir D. Ogorodnikov,
• Tatiana V. Petrenko and
• Andrei I. Khlebnikov

Beilstein J. Org. Chem. 2011, 7, 1526–1532, doi:10.3762/bjoc.7.179

• oxidation reactions. Oxidation of thioethers to sulfoxides and sulfones can be achieved by using different oxidants and catalysts [15], hydrogen peroxide being the most versatile and green among them [16]. Despite the simplicity of their preparation and potentially useful properties, azole-containing

• of compounds 8 and 5 (Figure 1), especially as the HOMO energy of sulfoxide 8 is even slightly higher, leading to its higher reactivity in oxidation reactions. Conclusion In summary, we have prepared new pyrazole- and benzotriazole-derived sulfones and sulfoxides that are interesting in view of their

• coordination chemistry and their potential biological activity. The lower reactivity and selectivity of benzotriazole-containing thioether in oxidation reactions is explained by the presence of electron-withdrawing heterocycles in proximity to the sulfur atom, but nevertheless, the corresponding sulfoxide or

Chimeric self-sufficient P450cam-RhFRed biocatalysts with broad substrate scope

• Aélig Robin,
• Valentin Köhler,
• Alison Jones,
• Afruja Ali,
• Paul P. Kelly,
• Elaine O'Reilly,
• Nicholas J. Turner and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2011, 7, 1494–1498, doi:10.3762/bjoc.7.173

• ; P450 monooxygenase; substrate engineering; Introduction P450 monooxygenases are a ubiquitous family of enzymes found in a wide variety of organisms in all domains of life. These enzymes catalyse oxidation reactions such as hydroxylation, epoxidation, N- and O-dealkylation and heteroatom oxidation

• of the hydroxylation of compounds 11, 13 and 15 has not yet been determined and is currently under investigation. Conclusion In summary, we have described a fast screening method that allows us to find new biocatalysts for oxidation reactions, either by screening P450 variants or by screening

• attractive for the further discovery and development of new oxidation activity. Oxidation reactions with P450cam-RhFRed mutants. Whole cell biotransformation of diphenylmethane to 4-hydroxydiphenylmethane with P450cam(Y96A)-RhFRed. Conversion (% relative peak-area by GC–MS of extracted reaction mixtures