Additive-controlled chemoselective inter-/intramolecular hydroamination via electrochemical PCET process

• Kazuhiro Okamoto,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2024, 20, 264–271, doi:10.3762/bjoc.20.27

• , entry 3); thus, the phosphate base plays a crucial role in N-alkylation, while its basicity is insufficient to promote aza-Michael addition (pKa of the conjugate acid of the phosphate base is 1.72 in H2O) [12]. Furthermore, N-alkylation proceeded in a divided cell (anodic chamber); thus, the possibility

• in vacuo and the resulting residue was subjected to 1H NMR spectroscopy or column chromatography. A divided-cell experiment was performed using an H-type cell (4G glass filter). Compound 1 (0.2 mmol), Bu4NPF6 (387 mg, 1 mmol), phosphate base (90 mg, 0.2 mmol), CH2Cl2 (10 mL), and methyl vinyl ketone

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 19F NMR analysis of BMIm-BF4 after anodic oxidation in a divided cell, which shows a peak at −147.3 ppm (besides the peak at −150.6 due to BF4−) (see Supporting Information File 1, Figure S1e), which is replaced by a peak at −144.0 ppm (referred to −150.6 ppm for BF4−) when the electrolysis is

• was set at −150.6 ppm in 19F NMR spectrum [112]. We thus carried out the anodic oxidation of pure BMIm-BF4 (divided cell, galvanostatic conditions) and stopped the electrolysis after 60 C (corresponding to 0.6 mmol of electrons). At the end of the electrolysis, 0.6 mmol of DIPEA were added to the

• oxidation of pure BMIm-BF4 (divided cell, galvanostatic conditions) and stopped the electrolysis after 60 C (corresponding to 0.6 mmol of electrons). At the end of the electrolysis, 0.6 mmol of DBU were added to the anolyte and the mixture was kept under stirring at room temperature for 30 min. Then the

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• polyene 14 (prepared in two steps) in multigram quantities [23]. The reaction employed a divided cell with substoichiometric amounts of magnesium(II) acetate (0.5 equiv) and catalytic copper(II) 3,5-diisopropylsalicylate (0.02 equiv) to allow the redox radical cyclization of polyene in 42% yield. A Tsuji

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

• benzyl iodides generated in situ. Electrolysis conditions: Constant current electrolysis until anodic potential 1.12 V vs Fc/Fc+, divided cell, reticulated vitreous carbon (RVC) anode(+). Electrochemical oxidative C–O/C–N coupling of alkylarenes with NHPI. Electrolysis conditions: Constant current

Electrogenerated base-promoted cyclopropanation using alkyl 2-chloroacetates

• Kouichi Matsumoto,
• Yuta Hayashi,
• Kengo Hamasaki,
• Mizuki Matsuse,
• Hiyono Suzuki,
• Keiji Nishiwaki and
• Norihito Kawashita

Beilstein J. Org. Chem. 2022, 18, 1116–1122, doi:10.3762/bjoc.18.114

• -chloroacetates in Bu4NBr/DMF using a divided cell equipped with Pt electrodes to produce the corresponding cyclopropane derivatives in moderate yields were discovered. The reaction conditions were optimized, the scope and limitations, as well as scale-up reactions were investigated. The presented method for the

• electrochemical production of cyclopropane derivatives is an environmentally friendly and easy to perform synthetic procedure. Keywords: alkyl 2-chloroacetates; cyclopropane derivatives; divided cell; electro-reduction; Introduction In organic chemistry, cyclopropanes and their related compounds have been

• derivatives could be formed in moderate yields through the electrochemical reduction [13][14][15][16][17][18][19][20][21] of alkyl 2-chloroacetates in a divided cell (Scheme 1, reaction 4). The in Abushanab’s study utilized metal lithium is one of the rarest and most expensive metals. In addition, the

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

• . The reported methods commonly carried out in a divided cell [29][30][31][32][33][34] or an undivided cell with sacrificial anodes [35], such as Al, Mg, and Sn, to prevent undesired oxidative reactions (Scheme 1b) [36][37][38][39]. While sacrificial anodes enable the reactions to be performed with a

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

• , Hokkaido 060-8628, Japan 10.3762/bjoc.18.105 Abstract Electrochemical Friedel–Crafts-type amidomethylation was successfully carried out by a novel electrochemical oxidation system using a quasi-divided cell and trialkylammonium tetrafluoroborates, such as iPr2NHEtBF4. Constant current electrolysis of

• 1,3,5-trimethoxybenzene or indoles in DMA containing 0.1 M iPr2NHEtBF4 using an undivided cell equipped with a Pt plate cathode and a Pt wire anode (a quasi-divided cell) resulted in selective formation of N-acyliminium ions of DMA at the anode, which reacted with arenes to give the corresponding

• amidomethylated products in good to high yields. Keywords: electrochemical oxidation; Friedel–Crafts type amidomethylation; N-acyliminium ion; quasi-divided cell; trialkylammonium salt; Introduction Oxidation of amides generates useful intermediates, N-acyliminium ions, which have been widely used in organic

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

• per l’Ingegneria, Sapienza University, via del Castro Laurenziano, 7, 00161, Rome, Italy 10.3762/bjoc.18.98 Abstract In this paper we present the first electrochemical generation of NHC carried out in a divided flow cell. The flow cell operated in the recycle mode. The need for a divided cell derived

• chamber (Figure 1). The requirement for a divided cell (a more complicated device than the undivided configuration) arises from the need to protect electrogenerated NHC from its anodic oxidation in the absence of a consumable anode. To ensure good sealing of the electrolysis cell, the sandwich-type

• arrangement of cell components was compressed between two end plates using a series of bolts. This design incorporated a solution inlet and a solution outlet for the chamber to allow uniform flow over the surface of the electrodes. In the present work, where a divided cell configuration was required, a proton

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

• ) was placed in the cathodic chamber of a divided cell (40 mL beaker, 3 cm diameter, 6 cm height) equipped with a platinum cathode (5 × 5 cm2), a platinum anode (2 × 1 cm2), and a ceramic cylindrical diaphragm (1.5 cm diameter). A 0.3 M solution of Bu4NClO4 in DMF (4 mL) was placed in the anodic chamber

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

• ) in the kinetic resolution of primary amines 60 via their electrocatalytic oxidation to the corresponding ketones 62, and remaining amines (R)-60 were obtained with very high enantioselectivity. The controlled potential electrolysis was carried out in a divided cell in the presence of a base and a

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

• An electrochemical version of the Corey–Winter reaction was developed giving excellent results in aqueous methanol media (MeOH/H2O (80:20) with AcOH/AcONa buffer 0.5 M as supporting electrolyte), using a reticulated vitreous carbon as cathode in a divided cell. The electrochemical version is much

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

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

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

• transformed to 25-hydroxycholesterol (2) in 13% yield (Scheme 1). The statement that the Tl(II)/HMP/O2 adduct, suggested to be a radical in nature, is responsible for cholesterol oxidation was based on the following observations. The electrolysis performed in the divided cell indicated that the oxidation of

• converted into chlorohydrin 12 under the reaction conditions, which implies it was not formed through an epoxide intermediate. Finally, no products were formed when the electrolysis was performed in a divided cell. It seems that a chlorine species (e.g. Clδ+…FeCl4δ−), produced from anodically generated

• chlorine (dichloromethane was the likely source), initiated the sequence of reactions leading to cholesterol oxidation products. A very similar result was obtained by Kowalski et al. [39]. They carried out the electrolysis of cholesterol in dichloromethane by using a divided cell, the cathode of which was

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

• that it can be efficiently converted to the corresponding diastereomeric amines with an excess of 3a in a divided cell under galvanostatic conditions employing an Hg pool cathode (see Scheme 2, pathway III) [26]. Here, we report a new synthetic route to optically pure 8-substituted menthylamines 1

• (6c and 7c, R2 = Ph) require prolonged reaction times and render slightly lower yields. Electrochemical reduction of 8-substituted menthone oximes The electrolyses were carried out in a divided cell using a Nafion® sheet as separator and platinum as anodic material. Since previous studies revealed

Switching the reaction pathways of electrochemically generated β-haloalkoxysulfonium ions – synthesis of halohydrins and epoxides

• Akihiro Shimizu,
• Ryutaro Hayashi,
• Yosuke Ashikari,
• Toshiki Nokami and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2015, 11, 242–248, doi:10.3762/bjoc.11.27

• )-5-decene We first examined the reactions of β-bromoalkoxysulfonium ion 3a-Br generated by the reaction of (Z)-5-decene (2a) with Br+/DMSO (1-Br) [21] (Scheme 1, X = Br). Bu4NBr in DMSO/CH2Cl2 (1:9 v/v) was electrochemically oxidized at −78 °C in a divided cell using Bu4NBF4 as a supporting

• , X = I). Bu4NI in DMSO/CH2Cl2 (1:9 v/v) was electrochemically oxidized at −78 °C in a divided cell using Bu4NBF4 as a supporting electrolyte until 2.1 F/mol of electricity was applied. After addition of 2a to the solution, the mixture was stirred at 0 °C to give 3a-I, which was characterized by NMR

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

• unprecedented neolignan-type dimeric compounds. Results and Discussion Cathodic reduction on BDD electrode The ester methyl cinnamate (1a) was electrolyzed under constant current electrolysis (CCE) conditions in a divided cell. Solvents used for the reactions played a significant role in providing the desired

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

• iodoalkoxylated products of type 5 (Scheme 3). The electrolysis was carried out in an H-type divided cell (4G glass filter) equipped with carbon fiber electrodes (see Supporting Information File 1). Each chamber was charged with 2,6-lutidine and TBABF4 in CH3CN (0.3 M) and additionally the 1,4-dienol and sodium

• ), dried over Na2SO4 and the solvent was removed under reduced pressure. The product was obtained after column chromatography (n-pentane/diethyl ether). General procedure for the electrochemical iodonium-induced alkoxylation of 1,4-dienols An H-type divided cell (4G glass filter) was equipped with a carbon

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

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

• hydride in combination with a radical initiator such as AIBN. Peters and co-workers described an electrochemical alternative using cathodically generated nickel(I) complexes as mediators [41][42]. Under potentiostatic conditions (C.P.E. = controlled potential electrolysis) in a divided cell

• of the iminium species under formation of oxazolidine or 1,3-oxazinane species 30. According to their protocol, 29 is electrolyzed under galvanostatic conditions in a divided cell, using a NaOMe/MeOH electrolyte and potassium iodide as electron transfer mediator. The method provides access to a

• conventional Wacker-type cyclizations, where stoichiometric amounts of co-oxidant are employed at elevated temperatures, the electrochemical version proceeds smoothly at room temperature. In the case depicted in Scheme 16, the electrolysis was carried out in a divided cell under galvanostatic conditions using

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

• formed, containing isomers of 3-pentenoic acid (C5), 3-hexenedioic acid (C6) and 3,7-decadienedioic acid (C10) (Table 1, entries 1–7). The product distribution is among other things influenced by the water and proton content in the reaction system. In a divided cell, in which the anolyte consists of 1

• were conducted in a divided cell, giving only moderate yields [114][115]. A drastic increase in efficiency was obtained by employing sacrificial anodes [116], especially magnesium anodes [117][118]. The cathode material is again of great importance, with silver and platinum giving the highest

• oxidation and reduction of respectively halides and halonium species. Therefore, the use of a membrane or glass frit can be interesting to minimize this effect. However, in a divided cell, the electrocarboxylation of chloroacetonitrile to cyanoacetic acid still appeared to give higher current efficiencies