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

• ][109][110][111][112][113]. Organic peroxides are widely used as oxidants in oxidative coupling processes [114][115][116][117][118][119][120]. Industrial-scale production of readily available and efficient initiators of free radical polymerization and effective biologically active compounds promotes the

Towards potential nanoparticle contrast agents: Synthesis of new functionalized PEG bisphosphonates

• Souad Kachbi-Khelfallah,
• Maelle Monteil,
• Margery Cortes-Clerget,
• Evelyne Migianu-Griffoni,
• Jean-Luc Pirat,
• Olivier Gager,
• Julia Deschamp and
• Marc Lecouvey

Beilstein J. Org. Chem. 2016, 12, 1366–1371, doi:10.3762/bjoc.12.130

• one step has been performed. Thus, tested oxidants were the Jones reagent [22], potassium permanganate [23], with catalytic o-iodoxybenzoic acid (IBX) in oxone [24] and catalytic 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) with bis(acetoxy)iodobenzene (BAIB) [25]. The first two conditions led to a

Synthesis of 2-oxindoles via 'transition-metal-free' intramolecular dehydrogenative coupling (IDC) of sp² C–H and sp³ C–H bonds

• Nivesh Kumar,
• Santanu Ghosh,
• Subhajit Bhunia and
• Alakesh Bisai

Beilstein J. Org. Chem. 2016, 12, 1153–1169, doi:10.3762/bjoc.12.111

• -arylamido esters with alkyl halides followed by a dehydrogenative coupling. Experimental evidences indicated toward a radical-mediated path for this reaction. Keywords: C−H functionalization; intramolecular dehydrogenative coupling (IDC); iodine; N-iodosuccinimide; oxidants; 2-oxindoles; Introduction The

• article, we disclose the scope and limitations of 'transition-metal-free' IDC of Csp2-H and Csp3-H using iodine and N-iodosuccinimide (NIS) as oxidants. In addition, we have also demonstrated the synthetic utility of oxidative coupling products in the syntheses of 3-substituted-2-oxindoles, via a

• suitable solvent, potential bases, oxidants etc. yielded the desired product in good yields i.e. 85%, 88%, and 90% in THF, dioxane, and DMSO, respectively (Table 1, entries 3, 5, and 8). However, in non-polar aromatic solvents like xylene, benzene, and toluene, poor yields (43–49%, Table 1, entries 4, 6

Nucleic acids through condensation of nucleosides and phosphorous acid in the presence of sulfur

• Tuomas Lönnberg

Beilstein J. Org. Chem. 2016, 12, 670–673, doi:10.3762/bjoc.12.67

• polymerization. Proposed oxidants for prebiotic phosphite chemistry include H2O2 and Fe(III). The present paper describes the polymerization of thymidine and triethylammonium phosphite, with elemental sulfur acting as the oxidant. Up to pentameric oligonucleotides with internucleosidic phosphorothioate linkages

Mycothiol synthesis by an anomerization reaction through endocyclic cleavage

• Shino Manabe and
• Yukishige Ito

Beilstein J. Org. Chem. 2016, 12, 328–333, doi:10.3762/bjoc.12.35

• mycobacteria for protection against foreign electrophilic agents such as oxidants, radicals, and drugs. In the detoxification pathway, MSH reacts with alkylating reagents and the resulting S-conjugates are subsequently cleaved at the amide bond by MSH S-conjugate amidase (Scheme 1) [4][5][6][7][8][9][10

Cascade alkylarylation of substituted N-allylbenzamides for the construction of dihydroisoquinolin-1(2H)-ones and isoquinoline-1,3(2H,4H)-diones

• Ping Qian,
• Bingnan Du,
• Wei Jiao,
• Haibo Mei,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2016, 12, 301–308, doi:10.3762/bjoc.12.32

• -methylallyl)benzamide (4a) and cyclohexane (2a) as model compounds (Table 1). As shown in Table 1, we found that the reactions did not happen or gave only a trace amount of the desired product with K2S2O8, AIBN, BPO and TBHP as oxidants (Table 1, entries 1, 3–5). PhI(OAc)2 and DCP could be used as oxidants

Base metal-catalyzed benzylic oxidation of (aryl)(heteroaryl)methanes with molecular oxygen

• Hans Sterckx,
• Johan De Houwer,
• Carl Mensch,
• Wouter Herrebout,
• Kourosch Abbaspour Tehrani and
• Bert U. W. Maes

Beilstein J. Org. Chem. 2016, 12, 144–153, doi:10.3762/bjoc.12.16

• use of (super)stoichiometric quantities of oxyanions of toxic metals like Mn(VII) and Cr(VI) [1][2]. The amount of waste these oxidants produce and limitations on their use by new legislation [3] has prompted scientists to search for more sustainable oxidation methods. The use of transition metal- or

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

• ][24][25][26]. Several new developments in the related hetero-Diels–Alder reaction of acylnitroso species have also been reported recently [27][28][29][30]. These methodologies generally involve in situ generation of the acylnitroso species, achieved using a variety of oxidants including vanadium- [28

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• produce supramolecular structures, and their TTF units stack face-to-face to form columnar structures using the fastener effect. Based on redox-active self-organizing supramolecular structures, conducting nanoobjects are constructed by doping of TTF oligomers with oxidants after the formation of such

Pd(OAc)₂-catalyzed dehydrogenative C–H activation: An expedient synthesis of uracil-annulated β-carbolinones

• Biplab Mondal,
• Somjit Hazra,
• Tarun K. Panda and
• Brindaban Roy

Beilstein J. Org. Chem. 2015, 11, 1360–1366, doi:10.3762/bjoc.11.146

• % yield of 5a with 52% conversion of starting material. Increasing the temperature to 90 °C (Table 1, entry 2) afforded 63% yield of 5a with 80% conversion of 4a. Then different oxidants [Cu(OTf)2, PhI(OAc)2, K2S2O8, (NH4)2S2O8, p-benzoquinone (BQ), oxone, AgOAc, molecular oxygen] were examined under

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

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

• oxidants [5]. In such experiments, the potential at the anode increases to a point where it matches the oxidation potential of the reduced chemical oxidant (Scheme 1). The reduced chemical oxidant is then oxidized in order to generate the active chemical oxidant. The chemical oxidant then performs the

• reason, the sunlight-driven oxidation reactions were extended to the recycling of chemical oxidants. Three examples are shown in Scheme 4 [12] where each was chosen for its unique feature related to the indirect electrochemical approach. In the first reaction (Scheme 4a), an asymmetric dihydroxylation

• oxidation strategies, which can be used to generate new carbon–carbon bonds, functionalize amides, and capitalize on the reagent-based selectivity associated with chemical oxidants. In all cases, the use of constant current electrolysis conditions allows the potential at the anode surface to be adjusted to

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

Electrochemical selenium- and iodonium-initiated cyclisation of hydroxy-functionalised 1,4-dienes

• Philipp Röse,
• Steffen Emge,
• Jun-ichi Yoshida and
• Gerhard Hilt

Beilstein J. Org. Chem. 2015, 11, 174–183, doi:10.3762/bjoc.11.18

• organic trihalide salts [30], N-bromosuccinimide or N-iodosuccinimide and its derivatives [31][32][33][34][35][36], or more specialised reagents such as bis(pyridinium)iodonium(I) tetrafluoroborate [37][38][39]. Next to those, the in situ oxidation of halogenide ions with strong oxidants such as oxone, Pb

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

• reactions, in which two different molecules are linked by a new bond accompanied by the elimination of a hydrogen atom from each molecule (Scheme 1) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]; however, these terms are also applied to a large number of various reactions with oxidants, which involve

• benzylideneaniline were subjected to the acetoxylation using the Pd(OAc)2/PhI(OAc)2 system [33]. More recently, reactions involving the same and some other directing groups were studied in more detail. In most of the studies, Pd(OAc)2 was used as the catalyst, and PhI(OAc)2 or peroxides served as the oxidants. The

• lower temperature (50 °C instead of 100 °C, as in the case of CH-reagents 22 and 23) [53]. The ortho-acetoxylation and methoxylation of O-methyl aryl oximes 31 with Pd(OAc)2 combined with such oxidants as oxone, potassium persulfate, and (diacetoxyiodo)benzene (Scheme 7, coupling products 32 and 33

A facile synthesis of functionalized 7,8-diaza[5]helicenes through an oxidative ring-closure of 1,1’-binaphthalene-2,2’-diamines (BINAMs)

• Youhei Takeda,
• Masato Okazaki,
• Yoshiaki Maruoka and
• Satoshi Minakata

Beilstein J. Org. Chem. 2015, 11, 9–15, doi:10.3762/bjoc.11.2

• reductants or oxidants, leading to low functional group compatibility. More importantly, the reductive methods i) and ii) hardly avoid the production of N-oxide of diazahelicenes as well as azoxynaphthalenes (Scheme 1), the N-oxides are quantitatively reduced by a strong reductant to the corresponding

• (Scheme 2, the upper reaction) [31]. During a thorough screening of oxidants for the rearrangement reaction, we found out that the use of tert-butyl hypochlorite (t-BuOCl) as an oxidant exclusively gave 7,8-diaza[5]helicene instead of the corresponding rearranged product in good yields. This preliminary

• reaction). Results and Discussion Initially, we began to identify the optimum reaction conditions (oxidants, bases, and solvents) for the oxidative ring-closure of BINAMs using 1a as the model substrate (Table 1, for the full details of the screening of reaction conditions, see Supporting Information File

Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

• Kuppusamy Bharathimohan,
• Thanasekaran Ponpandian,
• A. Jafar Ahamed and
• Nattamai Bhuvanesh

Beilstein J. Org. Chem. 2014, 10, 3031–3037, doi:10.3762/bjoc.10.321

• According to the report of Kolarovič et al., the decarboxylative CuAAC reaction occurs efficiently with a CuSO4/NaAsc/DMSO catalytic system [6]. The palladium-catalyzed oxidative dehydrogenative coupling reaction may be effected by various oxidants [42][43] such as Ag2O, AgOAc, Ag2CO3, Na2S2O8, Cu(OPiv)2

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

• catalysts are used in combination with various stoichiometric oxidants including oxygen [16][21]. However, nucleophilic trappings of resultant iminium salts are typically exemplified with highly stabilised carbon nucleophiles such as cyanides, nitronates, enolate equivalents and heterocycles (Scheme 1) [14

• organometallic addition after photoactivation (thus far precluded by the use of BrCCl3), compatibility might be accomplished in two ways. Firstly, moderate the reactivity of the organometallic to tolerate BrCCl3 or secondly, find alternative oxidants which tolerate the organometallic. Whilst the former looked

• side-reactions of the malonyl radical and diethyl malonate. We explored alternative alkyl halide oxidants that would form inert byproducts. No reaction was observed when substituting BrCCl3 with ClCH2CN (−0.72 V vs SCE [48]) but to our delight, BrCH2CN (−0.60 V vs SCE [48]) resulted in near

A general metal-free approach for the stereoselective synthesis of C-glycals from unactivated alkynes

• Shekaraiah Devari,
• Manjeet Kumar,
• Ramesh Deshidi,
• Masood Rizvi and
• Bhahwal Ali Shah

Beilstein J. Org. Chem. 2014, 10, 2649–2653, doi:10.3762/bjoc.10.277

• catalyzed rapid C-alkynylation of glycals with a wide variety of unactivated alkynes, i.e., arylacetylenes and aliphatic alkynes. The method circumvents the use of metal catalysts/co-oxidants and exhibits short reaction times, i.e., 2 min. This method may find use in a large number of reactions, which are

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

• (1) with phenylamines using oxidants such as K3Fe(CN)6, HIO3 and NaIO4 in aqueous alcohol. According to these authors, the oxidative phenylamination mechanism involves a radical cation intermediate generated by an electron transfer process from the phenylamine to the oxidant. Further electrophilic

New highlights of the syntheses of pyrrolo[1,2-a]quinoxalin-4-ones

• Emilian Georgescu,
• Alina Nicolescu,
• Florentina Georgescu,
• Florina Teodorescu,
• Daniela Marinescu,
• Ana-Maria Macsim and
• Calin Deleanu

Beilstein J. Org. Chem. 2014, 10, 2377–2387, doi:10.3762/bjoc.10.248

• peak areas of the final reaction products 4 to 5 were determined (Table 2). The results suggest that in the presence of an organic and/or inorganic base the formation of pyrrolo[1,2-a]quinoxalin-4-one derivatives 4 is favored, while in a neutral medium or in the presence of oxidants, such as TPCD [12

Pd/C-catalyzed aerobic oxidative esterification of alcohols and aldehydes: a highly efficient microwave-assisted green protocol

• Marina Caporaso,
• Giancarlo Cravotto,
• Spyros Georgakopoulos,
• George Heropoulos,
• Katia Martina and
• Silvia Tagliapietra

Beilstein J. Org. Chem. 2014, 10, 1454–1461, doi:10.3762/bjoc.10.149

• not require co-catalysts, co-oxidants or ligands. Results and Discussion Pd-catalyzed esterification can be performed with Pd(II) species [31][32][33][34][35][44]. The challenge of performing aerobic oxidation under MW irradiation in a preliminary investigation prompted us to select benzylalcohol and

An economical and safe procedure to synthesize 2-hydroxy-4-pentynoic acid: A precursor towards ‘clickable’ biodegradable polylactide

• Quanxuan Zhang,
• Hong Ren and
• Gregory L. Baker

Beilstein J. Org. Chem. 2014, 10, 1365–1371, doi:10.3762/bjoc.10.139

• ). This was not expected since acid 1 prepared by other methods did not decompose upon isolation (Scheme 2) [17]. The possible reason for this decomposition is that there might be certain oxidants present in ether phase after continuous extraction (for example, HNO2 and HNO3, verified by a rapid color

• examined which presumably would remove any residual oxidants. Product 1 was not detected in ether filtrate after addition of solid Na2SO3 to an ether solution of 1 and filtration to remove Na2SO3 solid. However, acid 1 can be recovered in lower yield after extracting the acidified aqueous solution of

• indicates that solid Na2S2O5 removes possible oxidants and simply enables the formation of undecomposed solid product 1 after drying in vacuo. Despite the moderate yield, this procedure represents a simple, economical and safe approach to synthesize precursor 1. Conclusion One simple, economical and safe

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

• single electron oxidants capable of this task, we elected to employ photooxidation catalysts. Additionally, we sought to select visible light-activated organic single electron oxidants that do not readily sensitize singlet oxygen [17][18][19]. For these reasons, we were attracted to the use of

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