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

• indole moiety to afford the target product 64 along with the regenerated Rh(III) catalyst. A silver-catalyzed intramolecular cascade amination/ring-opening/cyclization of a variety of substituted MCPs 69 was proposed by Fan and co-workers, which provided a simple and efficient way for the building of

• . Notably, this finding was the first example for silver-catalyzed regioselective C2-alkylation of heterorarenes with primary alkyl radicals, generated from cyclopropanols through a radical ring-opening process. Lopp’s group also reported an efficient approach for copper-catalyzed ring-opening and

• scope under mild conditions. Surprisingly, four- and five-membered cycloalkanols were suitable in this system. In 2015, Zhu’s group developed the silver-catalyzed ring-opening of cycloalkanols 91 with NCS 118 for the synthesis of distally chlorinated ketones 119 (Scheme 28) [108]. The reaction was

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• give dimethyl ester 98 (Scheme 25). Silver oxide-promoted methylation introduces a MeO-C4 unit. Regioselective aziridine ring opening in 99 was then carried out in the known way with benzyl alcohol or methanol to produce substituted dimethyl L-glutamates 100 and 101. To ensure clean deprotection in the

Gold-catalyzed ethylene cyclopropanation

• Silvia G. Rull,
• Andrea Olmos and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2019, 15, 67–71, doi:10.3762/bjoc.15.7

• development of a catalytic route for cyclopropane 1, we have not invested efforts in the characterization of such materials. The silver complex Tp(CF3)2,BrAg(thf) [19] (Table 1, entry 3) was not effective toward the aforementioned target, since only 5% of 1 was formed. In this case, the product derived from

• the insertion of the carbene CHCO2Et group into the C–Cl of the solvent was the major one, accordingly with previous work from this and other laboratories using silver-based catalysts [20][21]. Therefore, we moved onto gold-based catalysts that had already been validated for EDA decomposition and

• the solvent (4) constituted the main transformation. This is probably the effect of the silver in the reaction medium, since simple silver salts promote such reaction. The use of NaBArF4 delivered ethyl cyclopropanecarboxylate (1) in 62% yield, with only 2% of olefins 2 as byproducts, the remaining 36

Gold-catalyzed post-Ugi alkyne hydroarylation for the synthesis of 2-quinolones

• Xiaochen Du,
• Jianjun Huang,
• Anton A. Nechaev,
• Ruwei Yao,
• Jing Gong,
• Erik V. Van der Eycken,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2018, 14, 2572–2579, doi:10.3762/bjoc.14.234

• ). Conducting the AuPPh3Cl/AgOTf-catalyzed reaction in trifluoroethanol (TFE) led to improved results producing 8a in up to 97% yield (Table 1, entry 6). Thus, this greener alternative [63] to chlorinated solvents was selected as the solvent of choice for the further exploration. Changing the silver counterpart

Practical tetrafluoroethylene fragment installation through a coupling reaction of (1,1,2,2-tetrafluorobut-3-en-1-yl)zinc bromide with various electrophiles

• Ken Tamamoto,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 2375–2383, doi:10.3762/bjoc.14.213

• Ken Tamamoto Shigeyuki Yamada Tsutomu Konno Faculty of Molecular Chemistry and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan 10.3762/bjoc.14.213 Abstract (1,1,2,2-Tetrafluorobut-3-en-1-yl)zinc bromide was prepared by insertion of the zinc–silver couple

• quantitatively recovered (Table 1, entry 1). Interestingly, when a zinc–silver couple Zn(Ag) [34] was employed instead of zinc powder, the desired zinc insertion took place very smoothly to form the desired (1,1,2,2-tetrafluorobut-3-en-1-yl)zinc bromide (2-Zn) in 86% NMR yield, along with a small amount of a

Coordination-driven self-assembly of discrete Ru₆–Pt₆ prismatic cages

• Aderonke Ajibola Adeyemo and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2018, 14, 2242–2249, doi:10.3762/bjoc.14.199

• silver nitrate in methanol at room temperature for 3 hours gave the dinuclear arene–ruthenium(II) clips 1a,1b(NO3)2. As represented in Scheme 1, the self-assembly reactions of methanolic solutions of 1a,1b(NO3)2 and methanolic solution of the triplatinum metalloligand 2 at room temperature yielded the

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

• previous literature [30][31][46][47], a plausible reaction mechanism for cobalt-catalyzed alkoxylation was proposed. As shown in Scheme 4, initially, CoIIX2 could be oxidized to CoIIIX2OR in the presence of a silver salt and an alcohol. Based on the experiments and the density functional theory

Preparation and X-ray structure of 2-iodoxybenzenesulfonic acid (IBS) – a powerful hypervalent iodine(V) oxidant

• Irina A. Mironova,
• Pavel S. Postnikov,
• Rosa Y. Yusubova,
• Akira Yoshimura,
• Thomas Wirth,
• Viktor V. Zhdankin,
• Victor N. Nemykin and
• Mekhman S. Yusubov

Beilstein J. Org. Chem. 2018, 14, 1854–1858, doi:10.3762/bjoc.14.159

• selectively affords the respective iodine(V) product after heating at 60 °C for 16 h with almost quantitative conversion. The aqueous solution containing IBS-Na (as sodium salt) and inorganic products resulting from the reduction of NaIO4 was treated with silver nitrate to precipitate I– and IO3– anions. The

• precipitate of silver salts was filtered off, and the mother liquor was concentrated using blowing air to about half of the initial volume. The concentrated aqueous solution was left for several days resulting in the formation of a microcrystalline precipitate of IBS-Na isolated in 61% yield. 1H and 13C NMR

Investigations of alkynylbenziodoxole derivatives for radical alkynylations in photoredox catalysis

• Yue Pan,
• Kunfang Jia,
• Yali Chen and
• Yiyun Chen

Beilstein J. Org. Chem. 2018, 14, 1215–1221, doi:10.3762/bjoc.14.103

• group first used alkynylbenziodoxoles for decarboxylative radical alkynylation under silver salt and persulfate conditions [19]. In 2014, the Chen group discovered that alkynylbenziodoxoles (BI-alkyne) readily participated in photoredox catalysis as the radical alkynylation reagent [20], after which

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• method for the synthesis of 2-bromobenzotropone 26 starting from dihydronaphthalene (322) was also realized by Balci’s group (Scheme 54) [188]. After addition of dibromocarbene to 322, the obtained dibromocyclopropane 323 was submitted to silver ion-catalyzed ring expansion/hydrolysis in aqueous acetone

Iodine(III)-mediated halogenations of acyclic monoterpenoids

• Laure Peilleron,
• Tatyana D. Grayfer,
• Joëlle Dubois,
• Robert H. Dodd and
• Kevin Cariou

Beilstein J. Org. Chem. 2018, 14, 1103–1111, doi:10.3762/bjoc.14.96

• NIS [21] and does not require the use of a strong oxidant such as IBX [22]. Compared to the standard procedure for the preparation of acetoxyhypohalites that requires the use of expensive and potentially toxic silver salts [23], our method offers a more practical alternative. It also differs from the

Electrochemically modified Corey–Fuchs reaction for the synthesis of arylalkynes. The case of 2-(2,2-dibromovinyl)naphthalene

• Fabiana Pandolfi,
• Isabella Chiarotto and
• Marta Feroci

Beilstein J. Org. Chem. 2018, 14, 891–899, doi:10.3762/bjoc.14.76

• File 1, Table S1) evidence the catalytic effect of the silver cathode in the C–Br bond reduction (Ep1 is quite less negative on Ag cathode) [28][29], although this effect is more evident in DMF than in ACN. In any voltammogram, the cathodic peak at the less negative potential should be related to the

• influence the outcome of an electrosynthesis, so we carried out electrolyses of 1a using a glassy carbon cathode (Table 1, entry 8) and a silver cathode (Table 1, entry 9). In both cases the working potential was that of the first reduction wave. In the case of glassy carbon, the electrolysis could not be

• terminated as the current flow stopped very early [30]. When a silver cathode was used, a good yield of desired alkyne 2a was obtained (72%), along with a small amount of hydrogenated alkene 4a (6%). In order to increase the yield of alkyne 2a (and as 2a reduction potential is much more negative, vide infra

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• based on poly(acrylamide-co-acryl acid) (poly(AAm-co-AAc)) [117]. These nanogels were transformed into their catalytic counterparts by growing silver nanoparticles (Ag NPs) inside the cross-linked polymeric network. These catalytic nanogels were also used to catalyse the reduction of 4-nitrophenol to 4

Enhanced quantum yields by sterically demanding aryl-substituted β-diketonate ancillary ligands

• Rebecca Pittkowski and
• Thomas Strassner

Beilstein J. Org. Chem. 2018, 14, 664–671, doi:10.3762/bjoc.14.54

• and argon-flushed Schlenk tube was charged with 1-methyl-3-phenyl-1H-imidazol-3-ium iodide (1, 230 mg, 0.8 mmol) and silver(I) oxide (100 mg, 0.4 mmol). After the addition of 20 mL of dry DMF the reaction mixture was stirred under an argon atmosphere with the exclusion of light for two hours at room

• ,κC2‘][bis(2,3,5,6-tetramethylphenyl) propane-1,3-dionato-κO,κO‘]platinum(II) (3) The product was obtained following the general procedure reported for 2 using 1-methyl-3-phenyl-1H-imidazol-3-ium iodide (1, 230 mg, 0.8 mmol) and silver(I) oxide (100 mg, 0.4 mmol), dichloro(1,5-cyclooctadiene)platinum

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• CF3SO2Na by means of an oxidative system comprising catalytic amounts of silver(I) nitrate and potassium persulfate K2S2O8. Both atmospheric oxygen and K2S2O8 can be the source of the oxygen atom of the ketone moiety. A series of experiments that include the formation of TEMPO–CF3 (TEMPO: 2,2,6,6

• simple alkenes, sodium triflinate and diazonium salts. The CF3 radical was produced from CF3SO2Na by oxidation with H2O2 in the presence of silver nitrate. Then, CF3• was added to the terminal position of the alkene to give radical 26 that was trapped by the arenediazonium salt to form the radical cation

• into the final oxindole (Scheme 26). In an independent work Wang and co-workers demonstrated that silver nitrate was not necessary for the reaction to proceed in acetonitrile and water at 80 °C (Scheme 27) [48]. Again, N-acyl and N–H derivatives failed to deliver the desired products and meta

Binding abilities of polyaminocyclodextrins: polarimetric investigations and biological assays

• Marco Russo,
• Daniele La Corte,
• Annalisa Pisciotta,
• Serena Riela,
• Rosa Alduina and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2751–2763, doi:10.3762/bjoc.13.271

• modelled as a mixture of independent virtual weak bases. We already have employed these products as capping agents for the preparation of silver nanocomposites [37], which in turn have been tested as catalysts for nitroarene reduction and as antimicrobial agents in synergism with classical antibiotics [40

Ring-size-selective construction of fluorine-containing carbocycles via intramolecular iodoarylation of 1,1-difluoro-1-alkenes

• Takeshi Fujita,
• Ryo Kinoshita,
• Tsuyoshi Takanohashi,
• Naoto Suzuki and
• Junji Ichikawa

Beilstein J. Org. Chem. 2017, 13, 2682–2689, doi:10.3762/bjoc.13.266

• synthesis. We have already achieved the metal-catalyzed and acid-mediated cationic cyclization of 1,1-difluoro-1-alkenes. In the former case, we reported the palladium [6][7][8][9][10], indium [10][11][12][13], and silver-catalyzed construction of ring-fluorinated carbocycles and heterocycles [14]. In the

• elimination from 2a, 1,2-migration of the phenyl group, and deprotonation, followed by hydrolysis of the resulting doubly activated benzylic difluoromethylene unit (Scheme 2). Neither a combination of bis(pyridine)iodonium (IPy2BF4) and trifluoromethanesulfonic acid nor a combination of I2 and silver(I

Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• final saponification gave the monofluoroalkene-based dipeptide isostere 61. Finally, Fürstner’s group developed the silver-mediated fluorination of functionalized alkenylstannanes to access monofluoroalkenes [42]. Hydrostannation of the N-protected ynamines 62 followed by electrophilic fluorination with

• Pannecoucke and co-workers. Synthesis of Fmoc-Val-ψ[(E)-CF=C]-Pro by Pannecoucke and co-workers. Diastereoselective addition of Grignard reagents to sulfinylamines derived from α-fluoroenals with Me2Zn as additive. Silver-mediated fluorination of functionalized alkenylstannanes. Activity towards the calcium

Exploring mechanochemistry to turn organic bio-relevant molecules into metal-organic frameworks: a short review

• Vânia André,
• Sílvia Quaresma,
• João Luís Ferreira da Silva and
• M. Teresa Duarte

Beilstein J. Org. Chem. 2017, 13, 2416–2427, doi:10.3762/bjoc.13.239

• to approximately 80 °C. Both BioMOFs were obtained recurring to manual mechanochemistry. Due to the possibility of synergic effects with Ag+, a known antimicrobial agent, the new network with 4-aminosalicylic acid and silver is highly interesting, as it represents a promising candidate to future

Is the tungsten(IV) complex (NEt₄)₂[WO(mnt)₂] a functional analogue of acetylene hydratase?

• Matthias Schreyer and
• Lukas Hintermann

Beilstein J. Org. Chem. 2017, 13, 2332–2339, doi:10.3762/bjoc.13.230

• . More specifically, gold complex AuCl(PPh3) is not usually considered an alkyne hydration catalyst itself, but turns into a catalytically active gold(I) cation after activation with silver salt or Lewis acid [31][32][33][34]. Under the forcing microwave reaction conditions in aqueous methanol

Diosgenyl 2-amino-2-deoxy-β-D-galactopyranoside: synthesis, derivatives and antimicrobial activity

• Henryk Myszka,
• Patrycja Sokołowska,
• Agnieszka Cieślińska,
• Andrzej Nowacki,
• Maciej Jaśkiewicz,
• Wojciech Kamysz and
• Beata Liberek

Beilstein J. Org. Chem. 2017, 13, 2310–2315, doi:10.3762/bjoc.13.227

• the β anomer). Glycosylation of diosgenin with 2 was performed in dichloromethane by a “reverse” procedure: The glycosyl donor was added to the solution of diosgenin and the promoter (silver triflate) [31]. This procedure afforded the expected β glycoside 3 in 80% yield. The structure of 3 was

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

• Satoru Mori and
• Norio Shibata

Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224

• reflux conditions was attempted, but the reaction did not proceed because of the poor axial reactivity. Therefore, the axis substitution reaction for F-SubPc was carried out after activating its axial position by silver triflate to obtain an intermediate dimer. Finally, H-SubPc was condensed by the axial

• substitution reaction using the activation method by silver triflate to induce the desired trimer 34. Even in the trimer, an investigation of the spectroscopic properties suggested the transfer of energy between units. Each unit had an independent absorption property, but the fluorescence peak corresponding to

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• oxidative [4 + 1]-annulation of nitrosoalkenes with 1,3-dicarbonyl compounds (Scheme 37). Optimized reaction conditions require 2 equivalents of silver carbonate as oxidizer and K2CO3 as a base to generate nitrosoalkene from a halooxime precursor 1. The plausible mechanism involves the initial conjugate

• addition of dicarbonyl compounds to a nitrosoalkene followed by a silver-mediated radical cyclization of the resulting oximes 6 to final isoxazolines 100. Importantly, the reaction is well-tolerated by various substituents both in halooxime and in dicarbonyl compounds producing isoxazolines 100 in moderate

Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2017, 13, 2028–2048, doi:10.3762/bjoc.13.201

• 72. The latter was then intramolecularly glycosylated in the presence of silver triflate, tin(II) chloride, and 2,6-di-tert-butyl-4-methylpyridine (DTBMP). Finally, the tether was cleaved off using TFA to give pure 1,2-cis glycoside 73 in 63% yield over two steps. An alternative linker was developed

• alcohol showed good selectivity (α/β = 4.8:1) when boronic acid and NBS were employed. Control experiments with a thiophenyl or a thiobenzyl leaving group showed lower stereoselectivities and a slight reduction in yields. The addition of triflic acid or silver triflate resulted in a significant reduction

High-speed vibration-milling-promoted synthesis of symmetrical frameworks containing two or three pyrrole units

• Marco Leonardi,
• Mercedes Villacampa and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2017, 13, 1957–1962, doi:10.3762/bjoc.13.190

• catalytic amount of Ce(IV) ammonium nitrate (CAN) [17], which had been previously pre-mixed for 30–60 min to ensure the complete generation of the intermediate bis-β-enaminones 5, were added to the reaction vessel, together with silver nitrate, and the mixture was again submitted to milling for an