Mechanochemical synthesis of hyper-crosslinked polymers: influences on their pore structure and adsorption behaviour for organic vapors

• Sven Grätz,
• Sebastian Zink,
• Hanna Kraffczyk,
• Marcus Rose and
• Lars Borchardt

Beilstein J. Org. Chem. 2019, 15, 1154–1161, doi:10.3762/bjoc.15.112

• Information File 1, Figure S2) at around 310 °C. The residual mass of only 1.9% confirms the absence of both, excessive abrasion and oxidant inside the polymer. This is further supported by the SEM-EDX (scattering electron microscope, energy-dispersive X-ray spectroscopy) measurements showing both Cl and Fe

• surface area) achieved with the classical solvent-based approach (Sol-HCP, SSABET = 1450 m2g−1, Vp = 1.55 cm−3g−1) [11] could not be reached. In order to improve this property, we varied the mechanochemical reaction parameters such as milling time and amount of oxidant in a systematic (DOE) design of

Extending mechanochemical porphyrin synthesis to bulkier aromatics: tetramesitylporphyrin

• Qiwen Su and
• Tamara D. Hamilton

Beilstein J. Org. Chem. 2019, 15, 1149–1153, doi:10.3762/bjoc.15.111

• placing reactants in a sealed tube at high temperatures (150 °C or higher) for 24 to 48 hours in the absence of air or any oxidant. Not every substituted benzaldehyde could survive this process and yield the porphyrin. Adler and Longo later introduced refluxing propionic acid (141 °C) open to air as a

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• acid derivative as one of the substrates of the reaction, together with an amine and a third reagent that provides the carbon atom needed to complete the cyclic moiety. Thus, Shi et al. [76] reacted benzoic acid derivatives 1, amides 2 and DMSO (3) in the presence of DDQ as oxidant and without any

Azologization of serotonin 5-HT₃ receptor antagonists

• Karin Rustler,
• Galyna Maleeva,
• Piotr Bregestovski and
• Burkhard König

Beilstein J. Org. Chem. 2019, 15, 780–788, doi:10.3762/bjoc.15.74

• , nitrosoquinoxaline 3 was synthesized in a two-step procedure starting from 2-chloroquinoxaline (1), which was transformed into its oxime 2 using hydroxylammonium chloride [64]. The subsequent oxidation was performed using periodic acid as oxidant [65]. The subsequent reaction with differently substituted anilines in

Efficient synthesis of 4-substituted-ortho-phthalaldehyde analogues: toward the emergence of new building blocks

• Clémence Moitessier,
• Ahmad Rifai,
• Pierre-Edouard Danjou,
• Isabelle Mallard and
• Francine Cazier-Dennin

Beilstein J. Org. Chem. 2019, 15, 721–726, doi:10.3762/bjoc.15.67

• cyclisation in a basic medium of 2 then occurred to generate 4,5-dihydroisobenzofuran-5-ol (3) [19]. At this step, Cao et al. [17] have chosen the direct oxidation of 4,5-dihydroisobenzofuran-5-ol (3) to obtain 4-HO-OPA by using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an oxidant. However, the yield

Selective benzylic C–H monooxygenation mediated by iodine oxides

• Kelsey B. LaMartina,
• Haley K. Kuck,
• Linda S. Oglesbee,
• Asma Al-Odaini and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2019, 15, 602–609, doi:10.3762/bjoc.15.55

• hypervalent iodine species as a terminal oxidant. Combinations of ammonium iodate and catalytic N-hydroxyphthalimide (NHPI) were shown to be effective in the selective oxidation of n-butylbenzene directly to 1-phenylbutyl acetate in high yield (86%). This method shows moderate substrate tolerance in the

• ) scaffold have been intensely studied for their ability to mediate hydrogen atom abstraction using a terminal oxidant of molecular oxygen [40][41][42][43][44][45]. NHPI has also been used in the effective C–H to C–O functionalization of benzylic positions using oxidants other than molecular oxygen including

• hydrocarbons [53], was also able to catalyze the reaction yielding compound 3a in 81% yield. The NHPI-catalyzed oxidation of n-butylbenzene (1a) was shown to be compatible with a variety of iodine(V) and iodine(VII) oxidants. As shown in Table 1, the use of potassium periodate as the terminal oxidant in the

Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions

• Nicholas L. Reed,
• Madeline I. Herman,
• Vladimir P. Miltchev and
• Tehshik P. Yoon

Beilstein J. Org. Chem. 2019, 15, 351–356, doi:10.3762/bjoc.15.30

• describe a method for alkene oxyamination and diamination that utilizes simple carbamate and urea groups as nucleophilic heteroatom donors. This method uses a tandem copper–photoredox catalyst system that is operationally convenient. The identity of the terminal oxidant is critical in these studies. Ag(I

• ligand sets might be required, as in enantioselective catalytic oxidation reactions or certain cross-coupling applications. We wondered, therefore, if catalytic loadings of copper(II) salts might be used in these reactions by adding a secondary terminal oxidant to turn over the intermediate copper(I

• dioxygen for this purpose is frequently exploited to effect synthetically useful copper-catalyzed aerobic oxidation reactions [27][28]. However, the use of molecular oxygen as a terminal oxidant presents unique challenges in photoredox chemistry. Triplet dioxygen rapidly quenches the excited state of most

Metal-free C–H mercaptalization of benzothiazoles and benzoxazoles using 1,3-propanedithiol as thiol source

• Yan Xiao,
• Bing Jing,
• Xiaoxia Liu,
• Hongyu Xue and
• Yajun Liu

Beilstein J. Org. Chem. 2019, 15, 279–284, doi:10.3762/bjoc.15.24

• showed it served not only as a solvent but also as an oxidant. The developed reaction system required neither a metal catalyst nor a ligand. This simple method is expected to have potential application in both laboratory and industry. Representative examples of biologically active 2-mercaptobenzoxazoles

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• [2,3-c]dihydrocarbazoles 70 and [2,3-c]carbazoles 71 (Scheme 15) [91]. This process permitted the use of readily available and cheap AgOAc as the catalyst and oxidant, and DMF as the solvent. Notably, the product 70 was easily transformed into 71 in the presence of chloranil (1.4 equiv) at 120 °C under

• using AgF2 as both oxidant and fluorine atom source via the silver(II)-mediated ring-opening and fluorination of cyclopropanols 91 (Scheme 32) [112]. Through this method, a fluorine atom could easily be introduced in the β-position of a ketone. The mechanism is outlined in Scheme 32, the Ag-alkoxide

• ring-opening and difluoromethylthiolation of cyclopropanols 91 with PhSO2SCF2H 142 for the synthesis of difluoromethylthioethers 143 was reported by Shen and co-workers (Scheme 38) [118]. AgNO3 was utilized as catalyst, K2S2O8 as oxidant, and SDS (sodium dodecyl sulfate) as addictive in water. The SDS

Mn-mediated sequential three-component domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction towards annulated imidazo[1,2-a]pyridines

• Olga A. Storozhenko,
• Alexey A. Festa,
• Delphine R. Bella Ndoutoume,
• Alexander V. Aksenov,
• Alexey V. Varlamov and
• Leonid G. Voskressensky

Beilstein J. Org. Chem. 2018, 14, 3078–3087, doi:10.3762/bjoc.14.287

• , complicated by the need of an oxidant to fulfil the final aromatization. Following our interest in domino [42][43] and MCR chemistry [44][45] and taking an advantage of 2-iminochromene reactivity, herein we report a sequential three-component domino reaction of salicylaldehydes 2 and N-(cyanomethyl)pyridinium

• product 4. It is worth noting, that the conversion of 3 to 4 is a constant side reaction, occurring even at rt and complicating the process. Since the air oxygen was not enough to deliver the needed cyclization, we started to look for an appropriate oxidant. The addition of 1.1 equiv diacetoxyiodobenzene

• (PIDA) as an external oxidant on the second step and changing the solvent to trifluoroethanol allowed the isolation of the desired product 5a with 25% yield after 2 h reflux (Table 1, entry 2), while leaving the reaction at rt for 7 days gave the compound 5a with 30% yield (Table 1, entry 3). Further

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• . That's why the excited photoredox catalyst is at the same time a stronger oxidant and a stronger reductant than its ground state. Therefore, the PC can react more easily with an oxidant or a reductant (see in Figure 1) [16]. By addition of another reduction or oxidation agent, the catalytic cycle can be

Synthesis of indole–cycloalkyl[b]pyridine hybrids via a four-component six-step tandem process

• Muthumani Muthu,
• Rakkappan Vishnu Priya,
• Abdulrahman I. Almansour,
• Raju Suresh Kumar and
• Raju Ranjith Kumar

Beilstein J. Org. Chem. 2018, 14, 2907–2915, doi:10.3762/bjoc.14.269

• cyclization with the carbonyl to give 11, which subsequently undergoes dehydration to yield the cyclododeca[b]pyridine-3-carbonitrile 12. The intermediate 12 upon oxidative aromatization by molecular oxygen as the sole oxidant yields the indole–cyclododeca[b]pyridine-3-carbonitrile 7f. This four-component

Molecular iodine-catalyzed one-pot multicomponent synthesis of 5-amino-4-(arylselanyl)-1H-pyrazoles

• Camila S. Pires,
• Daniela H. de Oliveira,
• Maria R. B. Pontel,
• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Diego Alves,
• Raquel G. Jacob and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2018, 14, 2789–2798, doi:10.3762/bjoc.14.256

• hydroperoxide in dichloromethane at room temperature for 2 h, the respective diazo aromatic compound 6 could be obtained in 50% yield (Scheme 5). As can be seen, the reaction proceeded smoothly allowing formation of the new N=N bond without cleavage of the C–Se bond under the oxidant media and the presence of

DABCO- and DBU-promoted one-pot reaction of N-sulfonyl ketimines with Morita–Baylis–Hillman carbonates: a sequential approach to (2-hydroxyaryl)nicotinate derivatives

• Soumitra Guin,
• Raman Gupta,
• Debashis Majee and
• Sampak Samanta

Beilstein J. Org. Chem. 2018, 14, 2771–2778, doi:10.3762/bjoc.14.254

• DABCO, followed by aromatization using DBU as a base in an open-flask has been developed. This smart oxidant metal-free C–C/C–N bond forming process leads to an array of functionalized nicotinates/nicotinonitriles possessing an interesting phenolic moiety at C6 position in good to high yields. Moreover

Transition metal-free oxidative and deoxygenative C–H/C–Li cross-couplings of 2H-imidazole 1-oxides with carboranyl lithium as an efficient synthetic approach to azaheterocyclic carboranes

• Lidia A. Smyshliaeva,
• Mikhail V. Varaksin,
• Pavel A. Slepukhin,
• Oleg N. Chupakhin and
• Valery N. Charushin

Beilstein J. Org. Chem. 2018, 14, 2618–2626, doi:10.3762/bjoc.14.240

• reaction of 2,2-dimethyl-4-phenyl-2H-imidazole 1-oxide (1a) with carboranyllithium 2. The experiments performed have shown effects of the used oxidants, temperature regime, and exposure time after addition of an oxidant into the reaction mixture. As a result, the optimal conditions have been found to

• involve the use of DDQ as oxidant and refluxing of the reaction mixture in argon atmosphere for 1 h (Table 2, entry 12). It has also been observed that further increase in the exposure time does not improve yields (39–52%) of the target carboranyl-substituted imidazole 1-oxides 5a–d (Scheme 1). Besides

Synthesis of aryl sulfides via radical–radical cross coupling of electron-rich arenes using visible light photoredox catalysis

• Amrita Das,
• Mitasree Maity,
• Simon Malcherek,
• Burkhard König and
• Julia Rehbein

Beilstein J. Org. Chem. 2018, 14, 2520–2528, doi:10.3762/bjoc.14.228

• , electron poor arenes are required. In this article, we report the development of a mild and efficient oxidative photocatalytic method of thiolation of electron-rich di- and trimethoxybenzene arenes with aryl disulfides and (NH4)2S2O8 as terminal oxidant (Scheme 2). Results and Discussion 1,2,4

• very slow when air was used as an oxidant, also it led to various oxidation products of the sulfur and the degradation of the photocatalyst was observed upon irradiation. Therefore, (NH4)2S2O8 was used as terminal oxidant. The addition of tert-butyl hydroperoxide (TBHP) as an oxidant led to degradation

• of the reaction mixture, also when nitrobenzene (PhNO2) was used as oxidant, trace amounts of product were observed along with the formation of aniline, likely arising from the regeneration of the catalyst. Control experiments confirmed that light and photocatalyst were essential for the arylation

The mechanochemical synthesis of quinazolin-4(3H)-ones by controlling the reactivity of IBX

• Md Toufique Alam,
• Saikat Maiti and
• Prasenjit Mal

Beilstein J. Org. Chem. 2018, 14, 2396–2403, doi:10.3762/bjoc.14.216

• ]. During the reaction with the stronger oxidant PIDA, the basicity of the amine was regulated using an externally added acid salt, NaHSO4 (Figure 2a). In Figure 2b, a comparison in the reactivities of arylamines in the presence of non-iodine-based oxidant oxone [32] and IBX (iodine-based oxidant) is shown

• with IBX. c) Treatment of 2-aminobenzamide with IBX did not lead to any explosion. d) Reaction of 2-aminobenzamide and aldehydes in the presence of IBX as oxidant afforded quinazolin-4(3H)-ones at maximum interaction of the reactants, i.e., under ball-milling conditions. Comparison of the current work

A challenging redox neutral Cp*Co(III)-catalysed alkylation of acetanilides with 3-buten-2-one: synthesis and key insights into the mechanism through DFT calculations

• Andrew Kenny,
• Alba Pisarello,
• Arron Bird,
• Paula G. Chirila,
• Alex Hamilton and
• Christopher J. Whiteoak

Beilstein J. Org. Chem. 2018, 14, 2366–2374, doi:10.3762/bjoc.14.212

• functionalisation approach in 43% yield from the Cp*Rh(III)-catalysed coupling of allylic alcohols with acetanilide through a redox-active mechanism (Scheme 1b) [21], thus requiring stoichiometric oxidant (Cu(OAc)2), whereas the new protocol described in this report is intended to provide a more attractive redox

• -neutral alternative, obviating the requirement for addition of terminal oxidant (Scheme 1c). Herein, our results from this study will be reported and the difficulties of this translation will be explained through a DFT study of the mechanism, which will also be directly compared with the use of benzamides

A novel and practical asymmetric synthesis of eptazocine hydrobromide

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan,
• Kuaile Lin and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 2340–2347, doi:10.3762/bjoc.14.209

• , entry 3). When other oxidants, such as selenium oxide and manganese dioxide, were used, even at reflux temperature, no reaction took place (Table 2, entries 4 and 5). Owing to the concern of heavy metal pollution from the metal oxidant, organic oxidants were tested. Fortunately, DDQ in dioxane could

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• alkenes, which required a stoichiometric amount of oxidant. Herein, we wish to review the cobalt-catalyzed hydroarylation of alkynes, alkenes, allenes, enynes, imines, and isocyanates. These reactions usually proceed via either an oxidative addition of Ar–H to a low-valent cobalt to form A1 intermediate

A general and atom-efficient continuous-flow approach to prepare amines, amides and imines via reactive N-chloramines

• Katherine E. Jolley,
• Michael R. Chapman and
• A. John Blacker

Beilstein J. Org. Chem. 2018, 14, 2220–2228, doi:10.3762/bjoc.14.196

• generates and immediately reacts N-chloramines directly, avoiding purification and isolation steps. 2-Chloramines were produced from the reaction of styrenes with N-alkyl-N-sulfonyl-N-chloramines, whilst N-alkyl or N,N’-dialkyl-N-chloramines reacted with anisaldehyde in the presence of t-BuO2H oxidant to

• 76 and 77% observed, respectively. Reaction of N-chloramine with aldehyde Reaction of N-chloramines with aromatic and aliphatic aldehydes to form amides has been reported by Porcheddu [34]. Under these literature conditions, FeCl3 catalyst (0.15 mol %), t-BuO2H oxidant (3.6 equiv) and excess aldehyde

• . Unexpectedly, a control reaction omitting the FeCl3 catalyst resulted in 90% conversion following a two-hour reaction time (Table 3, entry 4). Removing the t-BuO2H oxidant reduced the reaction rate significantly, leading to 10% conversion under otherwise identical conditions (Table 3, entry 5), whilst fewer

Hypervalent iodine compounds for anti-Markovnikov-type iodo-oxyimidation of vinylarenes

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Mikhail A. Syroeshkin,
• Alexander A. Korlyukov,
• Pavel V. Dorovatovskii,
• Yan V. Zubavichus,
• Gennady I. Nikishin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2018, 14, 2146–2155, doi:10.3762/bjoc.14.188

• , Ostrovitianov str., 1, 117997 Moscow, Russian Federation National Research Center “Kurchatov Institute”, Akademika Kurchatova pl., 1, 123182 Moscow, Russian Federation 10.3762/bjoc.14.188 Abstract The iodo-oxyimidation of styrenes with the N-hydroxyimide/I2/hypervalent iodine oxidant system was proposed. Among

• formation of C–I and C–O bonds, which implies the radical pathway of the reaction. The iodo-oxyimidation of styrenes was studied in the model reaction of styrene (1a) with N-hydroxyphthalimide (2a). During the optimization, the oxidant and the iodine source, as well as the nature of the solvent and the

• reaction time were varied (Table 1). In general, the iodo-oxyimidation reaction is characterized by the following: The product 3aa is formed regardless what kind of hypervalent iodine compound is used (Table 1, entries 1-14) and Oxone (Table 1, entries 15 and 16) as the oxidant. The best yield of 3aa (90

Cobalt-catalyzed peri-selective alkoxylation of 1-naphthylamine derivatives

• Jiao-Na Han,
• Cong Du,
• Xinju Zhu,
• Zheng-Long Wang,
• Yue Zhu,
• Zhao-Yang Chu,
• Jun-Long Niu and
• Mao-Ping Song

Beilstein J. Org. Chem. 2018, 14, 2090–2097, doi:10.3762/bjoc.14.183

• substrates to optimize the alkoxylation reaction (Table 1, see more in Tables S1–S5 in Supporting Information File 1). To our delight, the desired product 3aa was obtained in 66% yield when using Co(OAc)2·4H2O as catalyst and Ag2CO3 as oxidant (Table 1, entry 1). Other cobalt salts such as CoF3 and CoF2 were

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• classed as a reductive quenching cycle (Figure 4). In a reductive quenching catalytic cycle, a species must act as an oxidant to return the photocatalyst to its native oxidation state. If ET occurs such that the catalyst is oxidised, the cycle is classed as an oxidative quenching cycle (Figure 5). In an

• coupling of aromatic aldehydes and a wide range of secondary amines, using mesitylacridinium salts as the photocatalysts (Scheme 1) [38]. The main advantage is the use of air as the oxidant, which converts the formed α-hydroxy amine into the desired amide. This makes for a much more atom economical and

• reaction specifically investigated the dimerization of thiols. Some of the experiments carried out by the group were in a flow chemistry set up, exemplifying the scalability of the procedure. In addition, the oxidant that achieves the transformation is molecular oxygen, making this a very sustainable route

Cobalt-catalyzed nucleophilic addition of the allylic C(sp³)–H bond of simple alkenes to ketones

• Tsuyoshi Mita,
• Masashi Uchiyama,
• Kenichi Michigami and
• Yoshihiro Sato

Beilstein J. Org. Chem. 2018, 14, 2012–2017, doi:10.3762/bjoc.14.176

• -catalyzed C–C bond formation using a stoichiometric amount of an oxidant [16][17][18][19][20][21][22], the π-allylpalladium intermediate [23][24][25] is an electrophilic species that exclusively reacts with nucleophiles. Therefore, it would be a formidable challenge for the generation of a nucleophilic π