Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• years and in the past, they were perceived as fleeting reaction intermediates. Recent progress in photoredox catalysis [6][7][8], electrochemistry [9][10], and the use of transition-metal (TM) catalysts in radical cross-coupling reactions [11] have dramatically expanded the use of radicals in synthesis

• reductant (typically Zn0 or Mn0) to both activate the NHPI ester and turn-over the catalytic cycle. However, the merger of Ni-catalysis and electrochemistry allows for the implementation of more convenient conditions in which these two crucial reductive steps can be mediated by the cathode (Scheme 34). In

• advancements in photochemistry, TM catalysis, NHC catalysis, and electrochemistry to show the generality of these RAEs in diverse mechanistic paradigms. Their application as radical progenitors continues to broaden the scope of radical-mediated reactions, especially in complex molecular settings, where issues

Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor

• Pengcheng Li,
• Daniel Kowalczyk,
• Johannes Liessem,
• Mohamed M. Elnagar,
• Dariusz Mitoraj,
• Radim Beranek and
• Dirk Ziegenbalg

Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9

• Pengcheng Li Daniel Kowalczyk Johannes Liessem Mohamed M. Elnagar Dariusz Mitoraj Radim Beranek Dirk Ziegenbalg Institute of Chemical Engineering, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany Institute of Electrochemistry, Ulm University, Albert-Einstein-Allee 47, 89081 Ulm

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• (without an acetylenic moiety as in 20) are themselves poor photosensitizers for singlet oxygen. Electrochemistry Cyclic voltammograms of compounds 11, 13, 15, 16, and 17 (in MeCN for compounds 11 and 15 and in CH2Cl2 for compounds 13, 16, and 17, all with 0.1 M Bu4NPF6 as supporting electrolyte) are shown

• Cary 50 UV–vis spectrophotometer scanning between 800 and 200 nm. All spectra were recorded with baseline correction in CH2Cl2 or toluene (HPLC grades) at 25 °C in a quartz cuvette with a 10 mm path length. Electrochemistry Cyclic voltammograms (CV) and differential pulse voltammograms (DPV) were

Synthesis of N-acyl carbazoles, phenoxazines and acridines from cyclic diaryliodonium salts

• Nils Clamor,
• Mattis Damrath,
• Thomas J. Kuczmera,
• Daniel Duvinage and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 12–16, doi:10.3762/bjoc.20.2

• fluorophors, previously shown to exhibit strong organic phosphorescence when mixed with specific additives [1][2][3][4][5]. Carbazole units are also found in drugs and natural products. They are also used in electrochemistry and as reagents in transamidation reactions [6][7][8][9][10][11][12]. The traditional

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

• complex organic compounds, widely used both in organic chemistry and in electrochemistry as raw materials for the preparation of different molecules of pharmaceutical and industrial interest [1][2][3][4][5][6][7][8][9]. Among the different organic transformations involving alkynes, their hydration is a

• [90][91]. Due to their wide electrochemical window, imidazolium ILs are commonly used in organic electrochemistry, simultaneously as solvents and supporting electrolytes [92][93][94]. In addition, the cathodic reduction (both in batch [95] and in flow [96]) can be exploited for the generation of N

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• . Their electrochemistry and reactivity were compared to those derived from 2-(4-(dimethylamino)phenyl)- (1b+) and 2-cyclohexylbenzo[d]imidazolium (1e+) salts. E(1+/1•) values for 2-aryl species are less reducing than for 2-alkyl analogues, i.e., the radicals are stabilized more by aryl groups than the

• donors (1gH, 1hH, 1iH). We also report crystal structures of several of these compounds and of several salts of the corresponding 1+ cations, and compare the electrochemistry and reactivity of these species. Results and Discussion Synthesis Although an unsymmetrical 12-like molecule, 2-diethoxyphosphoryl

• crystallographically characterized. Electrochemistry The 1+, 1H, and 12 species were investigated using cyclic voltammetry in THF/0.1 M Bu4NPF6 at a scan rate of 50 mV s−1. The voltammograms (shown for one series of compounds in Figure 6) were qualitatively similar to those reported and shown elsewhere for other

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• commercialized. Specifically, the company Twelve are making large advances in the electrolysis of carbon dioxide to carbon monoxide. Their contracts started with materials and have now expanded to fuels [10]. However, industrial electrochemistry either requires a dedicated power source, or plugging into a

• . Carpenter and co-workers also proposed, but did not test, recycling their amine with electrochemistry and light [32]. They cited a work by Itoh et al. who modified a proton exchange membrane electrolyzer with a Rh–Pt catalyst to generate hydrogen from water to hydrogenate benzene to cyclohexane in one

Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light

• Damiano Diprima,
• Hannes Gemoets,
• Stefano Bonciolini and
• Koen Van Aken

Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82

• [23][24] and methods for oxidation such as photochemistry, or electrochemistry have been developed [2][25]. However, low selectivity and the need for appropriate catalysts that are stable, cost-effective, and easy to remove remain problematic. Recently, catalyst-free procedures using O2 or air have

• separate” additives, a significant rate enhancement could be obtained with a positive impact on productivity rates. Results and Discussion There are a lot of similarities between electrochemistry and photoredox chemistry [33] as both rely on single-electron transfer processes to initiate reactions. In

• electrochemistry, the electron transfer occurs locally at the surface of the physical electrodes (typically located at a distance in the range of 200 μm to 2 cm) on which a potential is induced by an external potentiostat (Scheme 2). While for photoredox chemistry, the light-activated semiconductor catalyst

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

• , excellent alternative conditions are available to overcome these limitations, harvesting two different but correlated concepts: the use of multi-photon processes such as consecutive photoinduced electron transfer (conPET) and the combination of photo- and electrochemistry in synthetic photoelectrochemistry

• by a single catalyst entity [18][19][20][21]. 1.2 Photoelectrochemistry (PEC) Another important vehicle for SET is synthetic organic electrochemistry (SOE) [22][23]. While undoubtedly powerful, electrochemistry can suffer limitations in reaction selectivity because the constant application of high

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• were studied by steady state UV–vis absorption spectroscopy, transient photoluminescence spectroscopy, nanosecond/femtosecond transient absorption spectroscopy, electrochemistry, as well as DFT/TDDFT computations. We observed experimental evidence for the spin–vibronic coupling effect in the TADF

• -PTZ-F, etc. Electrochemistry study In order to obtain the energy of the CS state, the electrochemistry of these compounds was studied (Figure 5). A reversible oxidation wave at +0.29 V (vs Fc/Fc+) was observed for NI-PTZ-F, which is attributed to the oxidation of the PTZ part. Moreover, a reversible

Two-step continuous-flow synthesis of 6-membered cyclic iodonium salts via anodic oxidation

• Julian Spils,
• Thomas Wirth and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 27–32, doi:10.3762/bjoc.19.2

• Friedel–Crafts alkylation followed by an anodic oxidative cyclization yielded a defined set of cyclic iodonium salts in a highly substrate-dependent yield. Keywords: electrochemistry; flow chemistry; hypervalent compounds; iodine; oxidation; Introduction Hypervalent iodine compounds (HVI) are well

• electrochemistry is a highly economical tool that avoids chemical oxidants for synthesizing hypervalent iodine reagents [30]. Iodoarenes are suitable and well-established mediators in either in- or ex-cell electrochemical processes [31][32][33][34][35][36]. Nonetheless, HVIs, DIS and CDIS have been generated by

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

• ], and electrochemistry [22] all refuelled the field, allowing for more practical radical disconnections for total synthesis. Divergent synthesis of pyrone diterpenes (Baran 2018) [23]: The modestly sized family of pyrone diterpenes exhibits a wide range of bioactivities, ranging from immunosuppressive

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• that would otherwise be prohibitive or achieve readily scalable processes suitable for industrial applications [6][7][8][9]. In addition, flow chemistry has become the method of choice in modern research areas including photo- [10][11][12][13], electrochemistry [14][15][16], and biocatalysis [17][18

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

• /bjoc.18.158 Keywords: electron transfer; electrosynthesis; organic electrochemistry; redox-active materials; Electrochemistry is now a powerful tool in organic chemistry not only for analyzing the electron transfer behavior of organic molecules and macromolecules, but also for driving organic

• of organic electrochemistry for energy material applications. Organic semiconductor design for electron or hole transport is important for transistor and solar cell applications, and redox-active (but stable) organic and polymeric materials are promising for secondary batteries and redox flow

• macromolecular electrochemistry. The scope of this interdisciplinary issue ranges from synthetic aspects (such as electrosynthesis and reaction mechanisms) to materials science (including redox properties and devices). Shinsuke Inagi and Mahito Atobe Yokohama, October 2022

Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence

• Kaiyue Ye,
• Liyuan Cao,
• Davita M. E. van Raamsdonk,
• Zhijia Wang,
• Jianzhang Zhao,
• Daniel Escudero and
• Denis Jacquemin

Beilstein J. Org. Chem. 2022, 18, 1435–1453, doi:10.3762/bjoc.18.149

• , ΦΔ are much larger, up to 100% in dichloromethane (DCM) and ACN, likely due to the heavy-atom effect. Electrochemistry study The redox potentials of the dyads were studied with cyclovoltammetry (Figure 6, Table 3), and the Gibbs free energy changes of the charge separation (ΔGCS) and charge

Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives

• Oleg A. Levitskiy,
• Olga I. Aglamazova,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2022, 18, 1166–1176, doi:10.3762/bjoc.18.121

• base complexes; stereoselective electrosynthesis; voltammetric testing; Introduction Electrochemistry provides a direct access to highly reactive species by means of harnessing electrons or electron holes as reagents [1][2]. This capacity can be efficiently exploited in organic synthesis for rational

Electro-conversion of cumene into acetophenone using boron-doped diamond electrodes

• Mana Kitano,
• Tsuyoshi Saitoh,
• Shigeru Nishiyama,
• Yasuaki Einaga and
• Takashi Yamamoto

Beilstein J. Org. Chem. 2022, 18, 1154–1158, doi:10.3762/bjoc.18.119

• , first reported in 1944 [3], a wide variety of catalytic systems are still being reported [4][5][6][7][8][9][10][11][12]. Electro-organic synthesis refers to an organic synthetic method combined with electrochemistry [13][14]. A striking feature in electro-organic synthesis is the use of electricity as a

Radical cation Diels–Alder reactions of arylidene cycloalkanes

• Kaii Nakayama,
• Hidehiro Kamiya and
• Yohei Okada

Beilstein J. Org. Chem. 2022, 18, 1100–1106, doi:10.3762/bjoc.18.112

• electrochemistry in most cases, probably because both single-electron oxidation and reduction are made possible at the same surface [45]. This is especially true for the radical cation Diels–Alder reaction, since non-substituted β-methylstyrene, which was previously reported as an unsuccessful dienophile, was

• electrochemistry in many cases for these dienophiles, which accords well with our previous reports. The ring size effect of cycloalkanes was also clearly observed and cyclobutane was much more effective than the others. A similar trend was observed using some heterocycles, which also accorded well with the

Synthesis, optical and electrochemical properties of (D–π)₂-type and (D–π)₂Ph-type fluorescent dyes

• Kosuke Takemura,
• Kazuki Ohira,
• Taiki Higashino,
• Keiichi Imato and
• Yousuke Ooyama

Beilstein J. Org. Chem. 2022, 18, 1047–1054, doi:10.3762/bjoc.18.106

• practical concern with the objective of not only fundamental studies [1][2][3][4][5][6][7][8][9][10][11][12][13] in synthetic chemistry, electrochemistry and photochemistry, but also their potential applications to emitters for optoelectronic devices, such as organic light-emitting diodes (OLEDs) [14][15

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

• used as organocatalyst in two classical umpolung reactions of cinnamaldehyde: its cyclodimerization and its oxidative esterification. Keywords: Breslow intermediate; cathodic reduction; flow electrochemistry; N-heterocyclic carbene; oxidative esterification; Introduction Ionic liquids (ILs) are well

• reactions and usually the product separation is easy [4][5]. Among ILs, imidazolium derivatives are the most studied, in part due to their ease of synthesis, low cost and diverse applications from solvents and reagents in synthesis, to supporting electrolytes in electrochemistry [6]. The imidazolium cation

• as slow rates of conversion, low selectivity and reproducibility [26]. As a matter of fact, these problems can be addressed by using flow electrochemistry, usually achieving higher rates of conversion of reagents to products [27]. Moreover, electrochemical flow cells can have a very small gap between

Introducing a new 7-ring fused diindenone-dithieno[3,2-b:2',3'-d]thiophene unit as a promising component for organic semiconductor materials

• Valentin H. K. Fell,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Eman J. Hussien and
• Peter J. Skabara

Beilstein J. Org. Chem. 2022, 18, 944–955, doi:10.3762/bjoc.18.94

• its phase below its melting point. The limits of thermal stability were recorded by a 5% mass loss at elevated temperatures, as determined by thermal gravimetric analysis (TGA), and found to be 406 °C, indicating a high thermal stability (Figure S18 in Supporting Information File 1). Electrochemistry

Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons

• Hengjia Liu and
• Guohua Xie

Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83

• was assumed to be the reason for the decrease of the band gap. Meanwhile, the LUMO levels estimated from electrochemistry experiments (see Figure 11c and 11d) were also depressed from −3.60 eV (compound 19) to −3.96 eV (compound 19/B(C6F5)3) and from −3.59 eV (compound 20) to −4.12 eV (compound 20/B

Synthesis of α-(perfluoroalkylsulfonyl)propiophenones: a new set of reagents for the light-mediated perfluoroalkylation of aromatics

• Durbis J. Castillo-Pazos,
• Juan D. Lasso and
• Chao-Jun Li

Beilstein J. Org. Chem. 2022, 18, 788–795, doi:10.3762/bjoc.18.79

• perfluorinated chains into aromatic rings have been developed since the first reports of such transformation by George Tiers in 1960, and McLoughlin and Thrower in 1969 [2][3]. Most approaches have made extensive use of organometallic chemistry, radical initiators, photocatalysis, electrochemistry, and more

Complementarity of solution and solid state mechanochemical reaction conditions demonstrated by 1,2-debromination of tricyclic imides

• Petar Štrbac and
• Davor Margetić

Beilstein J. Org. Chem. 2022, 18, 746–753, doi:10.3762/bjoc.18.75

• , irradiation and electrochemistry as methods of chemical activation [8]. Based upon our experience in applications of this method to organic synthesis [9][10][11][12], we recognized its potential for the adjustment of conditions in zinc-mediated debromination reactions. Highly reactive dienophiles such as