1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF₃: the case of alkyne hydration. Chemistry vs electrochemistry

• Marta David,
• Elisa Galli,
• Richard C. D. Brown,
• Marta Feroci,
• Fabrizio Vetica and
• Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

• the aldol condensation products. Importantly, the ability to recycle the ionic liquid in subsequent reactions was successfully demonstrated. Keywords: alkyne hydration; boron trifluoride; electrochemical synthesis; ionic liquids; Introduction Alkynes are fundamental starting materials towards more

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• oxidative organocatalysis. Electrochemical DDQ-catalyzed intramolecular dehydrogenative aryl–aryl coupling. DDQ-mediated cross-dehydrogenative C–N coupling of benzylic substrates with azoles. Biomimetic o-quinone-catalyzed benzylic alcohol oxidation. Electrochemical synthesis of secondary amines by

Molecular and macromolecular electrochemistry: synthesis, mechanism, and redox properties

• Shinsuke Inagi and
• Mahito Atobe

Beilstein J. Org. Chem. 2022, 18, 1505–1506, doi:10.3762/bjoc.18.158

• reactions to produce value-added products. Electrochemical synthesis (or simply electrosynthesis) is increasingly recognized for the high academic and industrial importance, in line with the concept of green chemistry proposed in 1998 and the Sustainable Development Goals (SDGs) adopted by the United

A one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH₄I

• Shang-Feng Yang,
• Pei Li,
• Zi-Lin Fang,
• Sen Liang,
• Hong-Yu Tian,
• Bao-Guo Sun,
• Kun Xu and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2022, 18, 1249–1255, doi:10.3762/bjoc.18.130

• -alanine-assisted one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH4I (Scheme 1d). This electrochemical method features external-oxidant-free conditions and avoids the prefunctionalization of the substrates. Results and Discussion To

• dehydration to give the heterocyclic product 3. At the cathode, protons are reduced to release H2. Conclusion In conclusion, we have developed a one-pot electrochemical strategy for the synthesis of 2-amniothiazoles by the reaction of active methylene ketones with thioureas. The electrochemical synthesis was

• mmol) in DMSO 1 mL + H2O 14 mL, undivided cell, graphite plate anode and cathode, 30 °C, 5 mA/cm2, 6 F/mol; isolated yields are given. a8 F/mol. Up-scaling experiment. Control experiments. The proposed mechanism for the one-pot electrochemical synthesis of 2-aminothiazoles mediated by NH4I

Electrochemical formal homocoupling of sec-alcohols

• Kosuke Yamamoto,
• Kazuhisa Arita,
• Masashi Shiota,
• Masami Kuriyama and
• Osamu Onomura

Beilstein J. Org. Chem. 2022, 18, 1062–1069, doi:10.3762/bjoc.18.108

• formal homocoupling of benzhydrol did not occur under Kim’s reaction conditions. Thus, the development of an environmentally benign and efficient electrochemical protocol to access vic-1,2-diols would be still highly desirable. Herein, we report the sacrificial anode-free electrochemical synthesis of vic

Electrochemical Friedel–Crafts-type amidomethylation of arenes by a novel electrochemical oxidation system using a quasi-divided cell and trialkylammonium tetrafluoroborate

• Hisanori Senboku,
• Mizuki Hayama and
• Hidetoshi Matsuno

Beilstein J. Org. Chem. 2022, 18, 1040–1046, doi:10.3762/bjoc.18.105

• was carried out using Et3NHBF4 at −10 °C (Table 2, entry 3). Instead of Et3NHBF4, sterically more hindered iPr2NHEtBF4 was effective for the electrochemical synthesis to give the desired compound 2 in the highest yield, 72% by 1H NMR (Table 2, entry 4). These results strongly indicate that

First example of organocatalysis by cathodic N-heterocyclic carbene generation and accumulation using a divided electrochemical flow cell

• Daniele Rocco,
• Ana A. Folgueiras-Amador,
• Richard C. D. Brown and
• Marta Feroci

Beilstein J. Org. Chem. 2022, 18, 979–990, doi:10.3762/bjoc.18.98

• methanol and the Breslow intermediate. Electrochemical reduction of BMImBF4,a followed by the addition of elemental sulfurb. Flow cell, in recycling mode. Electrochemical synthesis of γ-butyrolactones 2a and 2b by conjugate umpolung reaction.a Electrochemical synthesis of esters 3a–c from cinnamaldehyde

Cathodic generation of reactive (phenylthio)difluoromethyl species and its reactions: mechanistic aspects and synthetic applications

• Sadanobu Iwase,
• Shinsuke Inagi and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2022, 18, 872–880, doi:10.3762/bjoc.18.88

• , these methods require various metal and organometallic reagents. On the other hand, electrochemical organic synthesis is a metal-free process and does not require any hazardous reagents and it produces less waste than conventional chemical syntheses. Therefore, electrochemical synthesis is desirable

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• -methyl-1,4-dimethoxynaphthalene, the construction of the naphthoquinone ring, the methylation of 1,4-naphthoquinone, and the electrochemical synthesis from 2-methyl-1,4-dihydroxynaphthalene. The works discussed in this section are grouped according to the synthetic approach that was employed to prepare

• catalyst, in the presence of 1,3-butadiene, presented the best yield (about 33%) (Scheme 9). This presented itself as a good synthetic route, considering that it used easily accessible reagents and there was no formation of polluting products. Electrochemical synthesis Although not common, menadione (10

• ) can be readily produced through electrochemical synthesis. This methodology allows the reuse of the electrolyte and demonstrates a significant substrate conversion. Raju and co-workers [94], for instance, reported the electrochemical synthesis of 10 from menadiol (14) using galvanostatic biphasic

Synthesis of piperidine and pyrrolidine derivatives by electroreductive cyclization of imine with terminal dihaloalkanes in a flow microreactor

• Yuki Naito,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2022, 18, 350–359, doi:10.3762/bjoc.18.39

• . Furthermore, piperidine and pyrrolidine derivatives could be obtained on preparative scale by continuous electrolysis for approximately 1 hour. Keywords: electrochemical synthesis; electrocyclization; flow microreactor; heterocyclic amines; imine; Introduction Heterocycles are a very important class of

• and sustainable synthetic method in the face of increasingly stringent environmental and economic constraints. In this context, several groups have demonstrated the electrochemical synthesis of piperidine and pyrrolidine derivatives by anodic oxidation [22][23][24][25][26]. In contrast, there has been

• their demonstration. Therefore, it is desirable to conduct the reductive cyclizations without the use of a mercury cathode, and the development of a simple, green, and efficient method for the electrochemical synthesis of heterocyclic amines is an important research target. The electrochemical flow

Electrocatalytic C(sp³)–H/C(sp)–H cross-coupling in continuous flow through TEMPO/copper relay catalysis

• Bin Guo and
• Hai-Chao Xu

Beilstein J. Org. Chem. 2021, 17, 2650–2656, doi:10.3762/bjoc.17.178

• alkyne 22 afforded 1.05 g (61%) of product 14 in 13 h (Scheme 3). The productivity could be increased if multiple reactors were employed in parallel [43]. A mechanism for the electrochemical synthesis was proposed based on reported studies (Scheme 4) [3][10]. Anodic oxidation of TEMPO generates the

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• synthesis in comparison to the electrochemical synthesis can be advantageous in obtaining desired patterns of substitution. Hence, this review article presents a comprehensive overview of the developments that have taken place in the last three decades in the field of chemical syntheses of azulene

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• exploiting electroorganic reactions to their fullest extent [15]. Asymmetric electrochemical synthesis refers to electroorganic reactions resulting in the introduction of one or more new elements of chirality into a target compound. The induction of asymmetry into achiral substrates through electrochemical

A diastereoselective approach to axially chiral biaryls via electrochemically enabled cyclization cascade

• Hong Yan,
• Zhong-Yi Mao,
• Zhong-Wei Hou,
• Jinshuai Song and
• Hai-Chao Xu

Beilstein J. Org. Chem. 2019, 15, 795–800, doi:10.3762/bjoc.15.76

• ] have studied the reactions of electrochemically generated NCRs. Particularly, we have recently reported an electrochemical synthesis of imidazo-fused N-heteroaromatic compounds via a radical cyclization cascade [31]. Building on this work, we report herein an atroposelective synthesis of

• reaction. A mechanism for the electrochemical synthesis was proposed based on the results from our previous work [31] and of this work (Scheme 3). The redox catalyst 1 is oxidized at the anode to give radical cation I. In the meanwhile, H2O is reduced at the cathode to afford HO− and H2. The base generated

• electrochemical synthesis of axially chiral biaryls. Reaction conditions: undivided cell, 2 (0.3 mmol), H2O (1 mL), MeCN (9 mL), 3.5 F mol−1. aIsolated yield of the major diastereomer. bDetermined by 1H NMR analysis of crude reaction mixture. cCombined yield of the two diastereomers. Proposed reaction mechanism

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

• electrochemical synthesis [2], and as mediators of living polymerization [10][11]. In organic synthesis more stable types of N-oxyl radicals can be used as carbon-centered radical scavengers [12], oxidation catalysts, mainly for conversion of alcohols to carbonyl compounds [11][13][14][15][16][17]. Less stable

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

• = 25 °C; solvent left: DMF/Et4NBF4 0.1 mol dm−3; right: ACN/Et4NBF4 0.1 mol dm−3. Variation of the amounts of 1a, 2a, and 3a with the number of Faradays of 1a. The Corey–Fuchs reaction. Electrochemical reduction of a carbon–halogen bond. Electrochemical synthesis of vinyl bromides [25]. Scope of this

• . Electrochemical synthesis of 9-ethyl-3-ethynyl-9H-carbazole (2b). Electrochemical synthesis of 1-ethynyl-4-methoxybenzene (2c). Electrochemical synthesis of 2-ethynylnaphthalene (2a). Electrolysis conditions optimization (Scheme 5).a Supporting Information Supporting Information File 58: Detailed experimental

Investigating radical cation chain processes in the electrocatalytic Diels–Alder reaction

• Yasushi Imada,
• Yohei Okada and
• Kazuhiro Chiba

Beilstein J. Org. Chem. 2018, 14, 642–647, doi:10.3762/bjoc.14.51

• solution. We assumed that the catalytic efficiency of the reaction would be further improved through optimizing and/or tuning the conditions in order to facilitate the bulk SET processes. As recently demonstrated by Baran [27][28] and Waldvogel [29][30], electrochemical synthesis has also proven to be

• highly scalable as well as sustainable. The longer chain length, also referred to as a higher “current efficiency” in this context, would enhance such advantages of the electrochemical synthesis. It should also be noted that the mechanism of electrochemical reactions can easily be studied since the

• electrochemical synthesis in that one electron can run the radical cation chain process up to 65 times. GC–MS monitoring showed a sigmoidal curve with an induction period. The monitoring was carried out in the presence of a large excess (10 equivalents) of isoprene (2), which might follow pseudo-first order

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• aldehydes. Synthesis of 1-cycloalkenetriphenylphosphonium salts by electrochemical oxidation of triphenylphosphine in the presence of cycloalkenes. Suggested mechanism for the electrochemical synthesis of 1-cycloalkenetriphenylphosphonium salts. Generation of α,β-(dialkoxycarbonyl)vinylphosphonium salts by

An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

• Carolina S. García,
• Paula M. Uberman and
• Sandra E. Martín

Beilstein J. Org. Chem. 2017, 13, 1717–1727, doi:10.3762/bjoc.13.166

• reactions has been reported, using a phase-transfer agent and focusing on the employment of ultralow catalyst concentrations [45]. Recently, we reported the electrochemical synthesis of stable Pd NPs by using platinum or vitreous carbon electrodes at room temperature via direct electroreduction of aqueous

• . Synthesis of Pd nanoparticles suspension by electrochemical reduction The electrochemical synthesis of PVP-Pd NPs was carried out as previously reported [46]. The experiments were achieved in a glass electrochemical cell equipped with a Pt disc working electrode (geometric area = 0.0746 cm2), a very large

C–H bond halogenation catalyzed or mediated by copper: an overview

• Wenyan Hao and
• Yunyun Liu

Beilstein J. Org. Chem. 2015, 11, 2132–2144, doi:10.3762/bjoc.11.230

• -workers [71] successfully achieved the selective mono-α-chlorination of β-keto esters/amides and 1,3-diketone 78 by employing an electrochemical synthesis via a catalysis by means of Cu(OTf)2. The synthesis of chlorinated carbonyl products 79 were acquired in a divided cell using aqueous HCl as chlorine

A new approach to ferrocene derived alkenes via copper-catalyzed olefination

• Vasily M. Muzalevskiy,
• Aleksei V. Shastin,
• Alexandra D. Demidovich,
• Namiq G. Shikhaliev,
• Abel M. Magerramov,
• Victor N. Khrustalev,
• Rustem D. Rakhimov,
• Sergey Z. Vatsadze and
• Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2015, 11, 2072–2078, doi:10.3762/bjoc.11.223

• current values of oxidation at the iron atom. These findings allow us to state that the synthesized molecules are promising starting materials for the electrochemical synthesis of ferrocene-containing conjugated polymers. Conclusion In conclusion, a novel stereoselective route to ferrocenyl haloalkenes

IR and electrochemical synthesis and characterization of thin films of PEDOT grown on platinum single crystal electrodes in [EMMIM]Tf₂N ionic liquid

• Andrea P. Sandoval,
• Marco F. Suárez-Herrera and
• Juan M. Feliu

Beilstein J. Org. Chem. 2015, 11, 348–357, doi:10.3762/bjoc.11.40

• electrochemical synthesis of PEDOT. The electrochemical properties of thin films of PEDOT are subsequently studied and compared with the behavior obtained in acetonitrile. Results and Discussion Cyclic voltammetry Figure 1 shows the cyclic voltammograms of EDOT in [EMMIM]Tf2N. The onset of the EDOT oxidation

Stereoselective cathodic synthesis of 8-substituted (1R,3R,4S)-menthylamines

• Carolin Edinger,
• Jörn Kulisch and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2015, 11, 294–301, doi:10.3762/bjoc.11.34

• electrochemical preparation of 8a. Electrochemical synthesis of 12a using different additives. Influence of the concentration of additive 11 on the electroreduction of 7b. Supporting Information Supporting Information File 76: Experimental details and 1H and 13C NMR spectra are provided. Acknowledgements

3α,5α-Cyclocholestan-6β-yl ethers as donors of the cholesterol moiety for the electrochemical synthesis of cholesterol glycoconjugates

• Aneta M. Tomkiel,
• Adam Biedrzycki,
• Jolanta Płoszyńska,
• Dorota Naróg,
• Andrzej Sobkowiak and
• Jacek W. Morzycki

Beilstein J. Org. Chem. 2015, 11, 162–168, doi:10.3762/bjoc.11.16

• /bjoc.11.16 Abstract 3α,5α-Cyclocholestan-6β-yl alkyl and aryl ethers were proved to be efficient cholesteryl donors in the electrochemical synthesis of glycoconjugates. 3α,5α-Cyclocholestan-6β-ol (i-cholesterol) and its tert-butyldimethylsilyl ether can also be used for this purpose. The i-cholesterol

• during electrochemical oxidation by cleavage of the carbon–oxygen bond in an intermediate radical-cation. For this reason, i-cholesteryl ethers seemed to be suitable donors of the cholesterol moiety for the electrochemical synthesis of cholesterol glycoconjugates. A series of i-cholesterol derivatives 6b

• ethers 6a–h is necessary for their reactions with sugar 7. No coupling occurred when chemical promoters were attempted. Conclusion 3α,5α-Cyclocholestan-6β-yl ethers are excellent cholesteryl donors for the electrochemical synthesis of cholesterol glycoconjugates. All of the tested compounds proved

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• conducted at low temperatures. The electrochemical synthesis of heterocyclic compounds can be considered as a mature discipline. The last comprehensive review dealing with electrochemical heterocycle generation has been published in 1997 by Tabaković [26]. Earlier reviews on different aspects of the

• intermolecular cyclizations Yoshida, Suga and co-workers investigated the electrochemical synthesis of five-membered heterocycles by integration of an intermolecular and an intramolecular step in one sequence. For this purpose, acyl iminium ions, electrogenerated as a cation pool at −78 °C, were converted at −23

• Undoubtedly, much progress has been made in the electrochemical synthesis of heterocyclic compounds since Tabaković's review appeared in 1997. Advances in anodic olefin coupling or electrochemically induced radical cyclization have made important contributions to this field. Moreover, the emergence of the