A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

Electrocatalytic hydrogenation of cyanoarenes, nitroarenes, quinolines, and pyridines under mild conditions with a proton-exchange membrane reactor

• Koichi Mitsudo,
• Atsushi Osaki,
• Haruka Inoue,
• Eisuke Sato,
• Naoki Shida,
• Mahito Atobe and
• Seiji Suga

Beilstein J. Org. Chem. 2024, 20, 1560–1571, doi:10.3762/bjoc.20.139

• decomposition of the substrates, and the desired products were not obtained. This system can be applied to large-scale syntheses. A similar yield of 7a was obtained when the reaction was scaled up (Scheme 5a). The electrolysis of 2.32 g of 6a gave 2.12 g of 7a (88% yield). Next, we examined the electroreduction

• synthesis. Therefore, the electroreduction of pyridine (8a) was performed (Table 6). First, the electroreduction of 8a was performed with 0.1 equiv of PTSA, and 1.0 equiv of PTSA was added after electrolysis to determine the yield by 1H NMR analysis (Table 6, entry 1). The yield of 9a·PTSA (26% yield) was

• under the optimized reaction conditions (Scheme 6). Electroreduction of 2-methylpyridine (8b) and 2-ethylpyridine (8c) afforded the corresponding 2-substituted piperidines 9b and 9c in 94% and 93% yields, respectively. The reaction of 3-methylpyridine (8d) gave 3-methylpiperidine (9d) in good yield. In

Transition-metal-catalyst-free electroreductive alkene hydroarylation with aryl halides under visible-light irradiation

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

Beilstein J. Org. Chem. 2024, 20, 1327–1333, doi:10.3762/bjoc.20.116

• that a reductive radical-polar crossover pathway is likely to be involved in this transformation. Keywords: aryl halides; C–C bond formation; electroreduction; radicals; visible light; Introduction Alkene hydroarylation is an attractive method for the construction of alkylarenes, which serve as

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

• alcohol derivatives. The present transformations smoothly proceed in a simple undivided cell under constant current conditions without the use of external chemical oxidants/reductants, and transition-metal catalysts. Keywords: alcohols; dimerization; electrooxidation; electroreduction; paired

• ][41][42][43][44]. The group of Wang recently reported the sacrificial anode-free electroreduction of benzophenone derivatives to afford vic-1,2-diols using over-stoichiometric NaN3 under acidic conditions, but appropriate precautions should be taken for in situ-generated explosive and toxic HN3 [45

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor: selectivity and utility

• Koichi Mitsudo,
• Haruka Inoue,
• Yuta Niki,
• Eisuke Sato and
• Seiji Suga

Beilstein J. Org. Chem. 2022, 18, 1055–1061, doi:10.3762/bjoc.18.107

• should be controllable by the cathode catalyst and electrochemical parameters. Fortunately, we found that chemoselective reduction of enones 1 can be carried out using different cathode catalysts (Pd/C or Ir/C). Results and Discussion Electroreduction of enones to ketones First, we chose cyclohex-2-en-1

• -one (1a) as a model compound, and the electroreduction of 1a was carried out using a PEM reactor (Figure 1a, a single path). Pd/C was used as a cathode catalyst. Without electricity, trace amounts of cyclohexanone (2a) and cyclohexanol (3a) were obtained (Table 1, entry 1). With a current of 2.5 mA⋅cm

• −1, 2a and 3a were obtained in a yield of 3% (current efficiency 66%) and 0.57% (current efficiency 5.7%), respectively (Table 1, entry 2). While 2a was obtained with moderate current efficiency, the yield was far from satisfactory. Therefore, electroreduction with a higher current density was

Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds: density functional theory study on product selectivity

• Naoki Kise and
• Toshihiko Sakurai

Beilstein J. Org. Chem. 2022, 18, 956–962, doi:10.3762/bjoc.18.95

• -dihydronaphthalene-1,4-diones (Scheme 1) [5]. In addition, we disclosed that the electroreduction of phthalimides with α,β-unsaturated carbonyl compounds under the same conditions and subsequent treatment with trifluoroacetic acid (TFA) produced 3- and 2-substituted 4-aminonaphthalen-1-ols (Scheme 2) [6]. In this

• context, we report here that the electroreduction of o-acylbenzoates 1 with acrylonitrile (2a) in the presence of TMSCl and subsequent treatment with 1 M HCl gives 2-cyanonaphthalen-1-ols 3 or 3-(3-cyanoethyl)phthalides 4 (Scheme 3). The product selectivity depends on the position of the methoxy

• Discussion The electroreduction of methyl 2-formylbenzoate (1a) with acrylonitrile (2a) was carried out in 0.3 M Bu4NClO4/THF in the presence of TMSCl at 0.1 A (2.5 F/mol). From the crude product, cyclized product 6a was obtained by column chromatography as a complex mixture of stereoisomers. Since compound

Controlled decomposition of SF₆ by electrochemical reduction

• Sébastien Bouvet,
• Bruce Pégot,
• Stéphane Sengmany,
• Erwan Le Gall,
• Eric Léonel,
• Anne-Marie Goncalves and
• Emmanuel Magnier

Beilstein J. Org. Chem. 2020, 16, 2948–2953, doi:10.3762/bjoc.16.244

• , CNRS, ICMPE, UMR 7182, 2 rue Henri Dunant, 94320 Thiais, France 10.3762/bjoc.16.244 Abstract The electroreduction of SF6 is shown at ambient temperature in acetonitrile using an array of platinum microelectrodes to improve the electrical detection. Its half reduction potential occurs at −2.17 V vs Fc

• +/Fc. The exact number of electrons for the full consumption of sulfur hexafluoride was determined and this gas further quantitatively transformed into environmentally benign fluoride anion and sulfur by electrochemical reduction. Keywords: electroreduction; fluoride anion; redox potential; sulfur

• reduction potential of SF6. To allow its electroreduction feasibility in acetonitrile, an electrochemical analytical approach was required [24]. This crucial step was supported by sensors which are based on a micro-disc-array of platinum ultramicroelectrodes (20 µm diameter) acting as multi-probe channels

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

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

• mixture during the electroreduction of acetophenone on a mercury cathode induces optical activity in the product (alcohol 24a, Scheme 7) [29]. Additionally, pinacol (23) was also obtained via dimerization along with chiral alcohols. The same method was reinvestigated by Wang and Lu in 2013 using a silver

• , conditions B). Based on a strychnine alkaloid-induced asymmetric electroreduction, Kopilov, Kariv and Miller showed that 4- and 2-acetylpyridines (1 and 25) could be reduced to the corresponding pyridylethanols (2 and 26, respectively) in presence of a catalytic amount of the alkaloid on a mercury cathode

• . Notably, the highest optical yields were achieved using strychnine (Scheme 8) [31]. Similarly, by applying modified electrolytic conditions, in 1993, Schoo and Schäfer increased the enantioselectivity of the alkaloid-catalyzed enantioselective electroreduction of 4-methylcoumarin (8) relative to that

Electrochemical Corey–Winter reaction. Reduction of thiocarbonates in aqueous methanol media and application to the synthesis of a naturally occurring α-pyrone

• Ernesto Emmanuel López-López,
• José Alvano Pérez-Bautista,
• Fernando Sartillo-Piscil and
• Bernardo A. Frontana-Uribe

Beilstein J. Org. Chem. 2018, 14, 547–552, doi:10.3762/bjoc.14.41

• precursor 6 from pyrone dioxolane 7. Putative reaction mechanism of the electrochemical Corey–Winter reaction. Electroreduction of thiocarbonates 4 and 6 in MeO/H2O 80:20 with AcOH/AcONa buffer 0.5 M as electrolytic media.a Supporting Information Supporting Information File 100: Experimental procedures and

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

• by electroreduction, entry 13, Table 1). Under the same reaction conditions, this in situ arranged catalytic system proved to be less active than the electrochemically preformed Pd NPs. Additionally, Pd NPs of an average size of (4 ± 1) nm and spherical shape were obtained when they were prepared

• area sheet of Pt (counter electrode) and a saturated calomel reference electrode (SCE). The Pd NPs dispersions were obtained through Pd(II) electroreduction in KNO3 (0.1 M) and H2PdCl4 (0.5 × 10−3 M) solutions (pH 3.0) by applying a current density pulse at the Pt electrode in the presence of PVP as

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

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

• which the reducing agent for oxygen (zinc) was replaced with electroreduction [24][25]. The chemical system was also applied to the oxidation of a side chain (Scheme 2) in protected cholesterol 3 [26], affording the corresponding 20-oxo derivative 4 (4.7%; yields are not corrected for recovered starting

• cholesterol and dioxygen to produce cholest-4-en-3-one and hydrogen peroxide [50]. Then, the cholesterol level can be determined from an amperometric response, which can either be measured as a decrease in the dioxygen electroreduction current or, more frequently, from the hydrogen peroxide reduction or

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

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

• , Yokohama 223-8521, Japan International Institute for Integrative Sleep Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan Japan Science and Technology Agency (JST), CREST, Hiyoshi 3-14-1, Yokohama 223-8522, Japan 10.3762/bjoc.11.21 Abstract The electroreduction reaction of

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• carboxylic acids from CO2 under relatively mild conditions, reactive organometallic nucleophiles such as Grignard reagents can be used, generating a large amount of waste [21][22][23][24]. Electroreduction of CO2 can be a worthy alternative for these dangerous energy-intensive processes, replacing toxic or

• electrons is determined by the applied voltage [25]. Since the electroreduction takes place on a cathode surface, the need for complex homogeneous organometallic catalysts is minimized. Furthermore, electricity will be increasingly of renewable origin in the future, making organic electrosynthesis a

• promising technology for environmentally friendly chemical processes [26]. The electroreduction of CO2 can be applied for the synthesis of fuels like formic acid [27], methanol [28] or methane [29] via two-, six- and eight-electron reductions, respectively (Scheme 2). This way electric energy from periodic

Novel indolin-2-one-substituted methanofullerenes bearing long n-alkyl chains: synthesis and application in bulk-heterojunction solar cells

• Irina P. Romanova,
• Andrei V. Bogdanov,
• Inessa A. Izdelieva,
• Vasily A. Trukhanov,
• Gulnara R. Shaikhutdinova,
• Dmitry G. Yakhvarov,
• Shamil K. Latypov,
• Vladimir F. Mironov,
• Vladimir A. Dyakov,
• Ilya V. Golovnin,
• Dmitry Yu. Paraschuk and
• Oleg G. Sinyashin

Beilstein J. Org. Chem. 2014, 10, 1121–1128, doi:10.3762/bjoc.10.111

• A 1–9 are reduced in the potential range from 0 to –2.5 V. A comparison of the peak potentials of the first reduction process of C60, A 1–9 and AIM 1–9 allows us to conclude that the electron transfer onto the fullerene sphere is the initial stage of the AIM electroreduction. The other cathodic