Electrochemical allylations in a deep eutectic solvent

• Sophia Taylor and
• Scott T. Handy

Beilstein J. Org. Chem. 2024, 20, 2217–2224, doi:10.3762/bjoc.20.189

• , but its effective realization is limited by the need for both a solvent as well as a supporting electrolyte to allow for the flow of current through the reaction. Although some imaginative options have been reported, they tend to be quite limited in scope. Room temperature ionic liquids (RTILs) were

O,S,Se-containing Biginelli products based on cyclic β-ketosulfone and their postfunctionalization

• Kateryna V. Dil and
• Vitalii A. Palchykov

Beilstein J. Org. Chem. 2024, 20, 2143–2151, doi:10.3762/bjoc.20.184

• ). Results and Discussion Reaction optimization Over the past two decades more than 300 various catalytic systems have been proposed for Biginelli chemistry, e.g., simple inorganic and organic acids, metal salts, metal oxides, ionic liquids, phosphines, nanocatalysts, organocatalysts, ion exchange resins [1

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• -pot process can be conducted in various solvents such as in PEG 400 [79], ionic liquids like 1-butyl-3-methylimidazolium hydroxide ((Bim)OH) [80], the nanoionic liquid 1-methylimidazolium trinitrocarbide ([[HMIM]C(NO2)3]) [81], N-methylpyridinium tosylate (NMPYT) [82], or glucose-based strong eutectic

Novel oxidative routes to N-arylpyridoindazolium salts

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

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• −1.2V to −1.3 V region (Table 1). In case of S2, the second reduction peak corresponds to the reduction of the carbonyl group. Thus, the electrochemical window for the new salts exceeds 3.5 V; that makes their molten forms perspective for application as ionic liquids. As follows from Table 1, oxidation

Syntheses and medicinal chemistry of spiro heterocyclic steroids

• Laura L. Romero-Hernández,
• Ana Isabel Ahuja-Casarín,
• Penélope Merino-Montiel,
• Sara Montiel-Smith,
• José Luis Vega-Báez and
• Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

• , such as a one-pot four-component synthesis and the use of ionic liquids as solvents [30]. Kanchithalaivan et al. [31] reported a library of 16-spiro pyrrolo[1,2-c][1,3]thiazoles of trans-androsterone and DHEA (49a and 49b, respectively). The syntheses were achieved through the 1,3-dipolar cycloaddition

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• under the cell potentials required to initiate the first single-electron transfer, resulting in benzylic cation IV [89][90]. This species can then be captured by fluoride to give benzylic fluoride product V. HF·amine ionic liquids are a popular choice of fluoride source in organic electrochemistry as

Synthesis of 1,2,3-triazoles containing an allomaltol moiety from substituted pyrano[2,3-d]isoxazolones via base-promoted Boulton–Katritzky rearrangement

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 1334–1340, doi:10.3762/bjoc.20.117

• ionic liquids [8][9]. Also, thermal and photochemical variants of studied recyclization are known in the literature [10][11]. Besides that, an unusual procedure for Boulton–Katritzky reaction including the use of surfactants is suggested by Fontana and co-workers [12]. Other heterocyclic systems capable

Synthesis and physical properties of tunable aryl alkyl ionic liquids based on 1-aryl-4,5-dimethylimidazolium cations

• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2024, 20, 1278–1285, doi:10.3762/bjoc.20.110

• Stefan Fritsch Thomas Strassner Physikalische Organische Chemie, Technische Universität Dresden, 01062 Dresden, Germany 10.3762/bjoc.20.110 Abstract We present a new class of tunable aryl alkyl ionic liquids (TAAILs) based on 1-aryl-4,5-dimethylimidazolium cations with electron-withdrawing and

• . With an electrochemical window of up to 6.3 V, which is unprecedented for TAAILs with an NTf2 anion, this new class of TAAILs demonstrates the opportunities that arise from modifications in the backbone of the imidazolium cation. Keywords: conductivity; electrochemical window; ionic liquids; tunable

• aryl alkyl ionic liquid; viscosity; Introduction Ionic liquids (ILs) are a special class of solvents generally defined as salts with melting points below 100 °C [1]. Due to their unique properties, e.g., their high thermal stability and their negligible vapor pressure [2][3], ILs have found widespread

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

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

• alkynes was studied in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIm-BF4) adding boron trifluoride diethyl etherate (BF3·Et2O) as catalyst. Different ionic liquids were used, varying the cation or the anion, in order to identify the best one, in terms of both efficiency and reduced

• 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

• with alternative solvents could represent an important innovation for alkyne hydration. In particular, ionic liquids (ILs) could represent a valid alternative to conventional organic solvents. ILs are generally liquid salts at or near room temperature, formed by large unsymmetrical organic cations and

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• -catalyzed sulfenylation by N-(sulfenyl)succinimides/phthalimides In 2012, Chen and co-workers found that in the reaction of N-(organothio)succinimides 1 and sodium sulfinates 2 using a Lewis acid in ionic liquids (ILs) and water as a green solvent system leads to the formation of thiosulfonates 3 (Scheme 2

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• [75]. However, the major drawback with using these catalysts in A3 reactions was the loss of the catalyst at the end of the reaction. Furthermore, on using Au(I), Ag(I), and Cu(I) in ionic liquids, as well as supported Au(III), Ag(I), CuI, and CuCl to catalyze A3 coupling reactions under heterogeneous

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• nanoorganocatalysts. Various solvent systems, such as aqueous conditions, different organic solvents, solvent-free conditions, ionic liquids, and DESs, have been reported in modified Clauson–Kaas reactions at room temperature, under thermal and microwave-assisted conditions. In the Clauson–Kaas reaction mechanism

• various acids and ionic liquids such as [hmim][HSO4], CH3COOH, [hmim][H2PO4], and [bmim][BF4] was investigated. Among these, [hmim][HSO4] proved to be the best catalyst providing higher yields in shorter time. This protocol provides a greener, environmental friendly, and a cleaner route for the synthesis

Friedel–Crafts acylation of benzene derivatives in tunable aryl alkyl ionic liquids (TAAILs)

• Swantje Lerch,
• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2023, 19, 212–216, doi:10.3762/bjoc.19.20

• liquids (TAAILs) has been developed. Through optimization of the metal salt, reaction conditions and ionic liquids, we were able to design a robust catalyst system that tolerates different electron-rich substrates under ambient atmosphere and allows for a multigram scale. Keywords: Friedel–Crafts

• acylation; homogeneous catalysis; ionic liquids; iron catalysis; TAAILs; Introduction The Friedel–Crafts acylation is one of the oldest metal-catalyzed reactions in organic chemistry [1] and allows for the synthesis of a broad range of diverse compounds [2][3][4][5]. Starting from electron-rich aromatic

• compounds, acylation is possible by an organic acid chloride/acid anhydride and a Lewis acid [6][7]. In the course of the development of ionic liquids (ILs) as a reaction medium for chemical reactions [8][9], the Friedel–Crafts reaction was also examined [10][11][12][13][14][15][16]. First protocols were

Cyclodextrin-based Schiff base pro-fragrances: Synthesis and release studies

• Attila Palágyi,
• Jindřich Jindřich,
• Juraj Dian and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2022, 18, 1346–1354, doi:10.3762/bjoc.18.140

• hydrolysis, oxidation, or light (Figure 1) [18]. Different substrates were used to synthesize pro-fragrances, like polymers [19], ionic liquids [20], rotaxanes [21], or saccharides [22]. To the best of our knowledge, no studies investigate the use of CDs as substrate. Linking the fragrance to CDs could

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

• known salts, at present used in a wide variety of chemical fields. The first definition of ionic liquids was given by Paul Walden in 1914: “they are materials composed of cations and anions, that melt around 100 °C or below as an arbitrary temperature limit” [1]. ILs are salts formed by non or weakly

• coordinated cations and anions, usually bulky organic cations and inorganic or organic anions such as −BF4, −PF6, −N(CF3SO2)2, etc. [2][3]. The physicochemical properties of RTILs (room temperature ionic liquids) are reported in the literature and include very low vapor pressure, and thus the possibility to

Synthesis of 5-unsubstituted dihydropyrimidinone-4-carboxylates from deep eutectic mixtures

• Sangram Gore,
• Sundarababu Baskaran and
• Burkhard König

Beilstein J. Org. Chem. 2022, 18, 331–336, doi:10.3762/bjoc.18.37

• replacement of organic solvents. The melts are stable against air and have very low vapor pressures resembling the properties of ionic liquids. In addition, the polarity of these melts is very high [33]. Recently, we have explored several organic transformations such as coupling reaction, cycloaddition

The PIFA-initiated oxidative cyclization of 2-(3-butenyl)quinazolin-4(3H)-ones – an efficient approach to 1-(hydroxymethyl)-2,3-dihydropyrrolo[1,2-a]quinazolin-5(1H)-ones

• Alla I. Vaskevych,
• Nataliia O. Savinchuk,
• Ruslan I. Vaskevych,
• Eduard B. Rusanov,
• Oleksandr O. Grygorenko and
• Mykhailo V. Vovk

Beilstein J. Org. Chem. 2021, 17, 2787–2794, doi:10.3762/bjoc.17.189

• derivatives with 4-chloroketones or 4-oxocarboxylic acids in ionic liquids [20][21][22][23] or refluxing acetic acid [24][25]. An alternative approach involves cascade cyclization of anthranilamides with 4-chlorobutanoyl chloride [26][27]. Also, reductive cyclocondensation of 2-nitrobenzamides and

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

• the halide anions Cl−, Br−, and I−-, respectively, UCST behavior can also be induced in polymeric ionic liquids by the addition of a suitable hydrophobic counterion, such as tetrafluoroborate BF4− [288][289]. In both cases, the critical phase transition temperature is strongly affected by the

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• for the water removal instead employed either DMSO or ionic liquids as additives for the water removal. The same condensation (of 17 to 127) was also performed by Clark et al. using a silica-coated microreactor with an AP-T catalyst deposited on the reactor’s walls [160]. The solvent-free approach

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• reaction suffers from drawbacks such as harsh reaction conditions, longer reaction time and low yields [70]. Several attempts have been made to improve the reaction conditions using various catalyst/reagents, ionic liquids etc. [71][72]. Contributing to this need, dos Anjos et al. [73] reported a base

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• nitrogen-based catalysts, ionic liquids [123][124] and alcoholysis of oxygen-containing polymers, such as polyesters, polycarbonates and polyamides, i.e., glycolysis of PET, wherein high temperatures and nearly stoichiometric amounts of catalysts are often required to achieve moderate yields of monomers

• catalysts in the form of ionic liquids (ILs) [209]. Advantages of metallated ILs include low flammability, high thermal stability and versatility. However, their “greenness” and toxicity are still debated [225][226]. Thus, amim[ZnCl3] (amin = 1-allyl-3-methylimidazolium, Table 4, entry 1) [227] and amim

• [ZnCl3] (bmim = 1-butyl-3-methylimidazolium, Table 4, entry 2) [228] were recently studied, showing higher catalytic activity compared to metal-free ionic liquids (i.e., bmim chloride), the conventional catalysts (i.e., ZnCl2, Zn(OAc)2) or the analogous Mn, Co and Cu ionic liquids. Typically, 80–85% BHET

Mesoionic tetrazolium-5-aminides: Synthesis, molecular and crystal structures, UV–vis spectra, and DFT calculations

• Vladislav A. Budevich,
• Sergei V. Voitekhovich,
• Alexander V. Zuraev,
• Vadim E. Matulis,
• Vitaly E. Matulis,
• Alexander S. Lyakhov,
• Ludmila S. Ivashkevich and
• Oleg A. Ivashkevich

Beilstein J. Org. Chem. 2021, 17, 385–395, doi:10.3762/bjoc.17.34

• attractive as environmentally friendly pyrotechnics [4], insensitive high-energy materials [5][6][7], and promising energetic ionic liquids [8][9][10]. The most interesting and less examined 5-aminotetrazole derivatives are tetrazolium-5-aminides, which can be depicted as 4 by analogy with other mesoionic

An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp³)–H bond functionalization under solvent- and catalyst-free conditions

• Divya Rohini Yennamaneni,
• Vasu Amrutham,
• Krishna Sai Gajula,
• Rammurthy Banothu,
• Murali Boosa and
• Narender Nama

Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259

• stability of 1-phenyl-2-(2-pyridyl)ethanol [32]. Different catalysts such as ionic liquids [33], CuFe2O4 [34], and Ca(OTf)2 [35] were also utilized. Due to the abundant importance of these products, several different approaches were reported (Scheme 1 and Scheme 2). These higher azaarene products were also

Ultrasound-assisted Strecker synthesis of novel 2-(hetero)aryl-2-(arylamino)acetonitrile derivatives

• Emese Gal,
• Luiza Gaina,
• Hermina Petkes,
• Alexandra Pop,
• Castelia Cristea,
• Gabriel Barta,
• Dan Cristian Vodnar and
• Luminiţa Silaghi-Dumitrescu

Beilstein J. Org. Chem. 2020, 16, 2929–2936, doi:10.3762/bjoc.16.242

• using “green” solvents, for example, low vapor pressure solvents such as ionic liquids [3], low volatile solvents such as glycerol, ethylene glycol and its oligomers, or nontoxic water solvent, as well as in heterogeneous media under solvent-free conditions [4]. Other advantages induced by sonication