Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• reactions starting from different reagents. In a first approach proposed by Meshram and co-workers, pyridin-2-one, O-tosylhydroxylamine and acetophenone treated in an ionic liquid assembled through the cascade formation of three C–N bonds to give the imidazo[1,2-a]pyridine scaffold 33 (Scheme 25) [43]. The

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

• substrates also increase yields. The ionic liquid [bmim][InCl4] can be used as a catalyst for the one-pot synthesis of pyrazoles 68 from 1,3-diketones, aldehydes, and hydrazines (Scheme 23) [101]. The synergistic effect between anion and cation favors high regioselectivity, and high yields can be observed in

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

• . prepared the Brønsted acid ionic liquid 7, based on the 1-(butyl-4-sulfonic)-3-methylimidazolium cation, (Scheme 4) and tested it in the model reaction reported in Scheme 2 (R = t-Bu), obtaining a 71% yield using 20 mol % of catalyst in ethanol as the solvent under reflux conditions. The yield could be

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

• the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][OTf]) for the fluorination of phthalides at the benzylic position (Figure 37) [95]. It was considered that the zwitterionic nature of the ionic liquid served two purposes. Firstly, to enhance the nucleophilicity of fluoride

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

• 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

• ionic liquid in addition to the possibility to introduce alkyl chains with varying length [30]. TAAILs have already been successfully used for the synthesis of nanoparticles and as solvents in catalysis [31][32]. Recently we have described the synthesis and physical properties of TAAILs which have been

• difference between Ered and Eox. The anodic limit Eox is mainly influenced by the anion of the ionic liquid, resulting in similar values for Eox for the NTf2-based TAAILs. The cathodic limit Ered depends on the cation and at what voltage the imidazolium cation is reduced. The substitution on the aryl ring

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

• his research group developed a novel sulfonic graphitic carbon nitride (g-C3N4-SO3H) as a nanosheet ionic liquid for the one-pot synthesis of BIMs [125]. Graphitic carbon nitride is a non-metal and non-toxic chemically stable nanostructure, which is obtained through a facile pyrolysis process that has

• not seen wide applications in nanocatalysis despite its numerous benefits. Therefore, Ozturk made it usable by coupling it with an ionic liquid, creating g-C3N4-SO3H nanoparticles, which displayed high catalytic activity for the Friedel–Crafts arylation of indoles with aldehydes. The optimum product

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

• the hydration of alkynes, named poly(ionic liquid)s (PILs), using trifluoroethanol as solvent [88][89]. One of the most studied classes of ILs in organic chemistry are 1,3-disubstitued imidazolium cations, which are cheap, liquid over a wide range of temperatures, and possess good solvating properties

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

• substitution to provide C2,C3-disulfenylated product 66 (Scheme 28). In the same year, Sutherland and Dodds disclosed a protocol for the C–H bond thioarylation of electron-rich arenes 4 like anisoles, acetanilides, phenols, and N-heterocycles in the presence of Fe(III) Lewis acid and ionic liquid [BMIM]NTf2 as

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

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

• Yolacan [88] reported the Clauson–Kaas reaction for the preparation of acidic ionic liquid 1-hexyl-3-methylimidazolium hydrogen sulfate ([hmim][HSO4])-catalyzed N-substituted pyrrole derivatives 71 under microwave irradiation (Scheme 34). To optimize of reaction conditions, the catalytic activity of

Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?

• Lukáš Marek,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61

• 70–95%). The presence of a base and the type of solvent seems to be an important factor for the reaction course. In toluene, ionic liquid or in refluxing ethanol without a base [16][19][20] or in the presence of weakly basic pyridine [17][18][21] (pKa = 5.23 in water, 3.4 in DMSO, 3.3 in DMF, and

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

• cost-efficient metal salts in a water and air stable ionic liquid is still hard to find [50][51]. In this contribution, we present the use of imidazolium-based tunable aryl alkyl ionic liquids (TAAILs) in a catalytic Friedel–Crafts acylation. This relatively new class of ionic liquids [52] previously

• derivatives (see Scheme 1). First, the arylimidazole is obtained through a ring closing reaction using an aniline derivative, glyoxal, formaldehyde and ammonium chloride. The following alkylation with hexyl bromide yields the bromido ionic liquid. TAAILs 1–6 are then formed by an anion exchange reaction using

• %, with minor formation of the ortho-isomer when using benzoic acid anhydride. Bromobenzene, which is electron poor and less reactive towards acylation, was also used as a substrate in the acylation reaction, but no product was observed. This indicates that the ionic liquid 6, having the same substituent

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

• Merve Karaman,
• Abhishek Kumar Gupta,
• Subeesh Madayanad Suresh,
• Tomas Matulaitis,
• Lorenzo Mardegan,
• Daniel Tordera,
• Henk J. Bolink,
• Sen Wu,
• Stuart Warriner,
• Ifor D. Samuel and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

• with an ionic liquid (EQEmax = 0.12%, Bmax = 10 cd m−2), which was incorporated to increase charge mobility within the emissive layer. We later showed that this emitter could act as host material in combination with a cyanine dye emitter [18]. The EQEmax for this host–guest device was higher than for

• operation. To solve this, we fabricated devices adding an ionic liquid (lithium hexafluorophosphate (LiPF6) or 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM:PF6) in a 4 to 1 molar ratio) and, in some cases, an electrolyte matrix (PEO (polyethylene oxide)), to improve the ionic mobility on the active

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

• flow electrolysis At this point, the preliminary results from flow electrochemistry may be compared with those reported in the literature for NHC formation using batch electrolysis. The comparison between these two techniques is not straightforward. In fact, in batch electrosynthesis, the ionic liquid

Synthesis of phenanthridines via a novel photochemically-mediated cyclization and application to the synthesis of triphaeridine

• Songeziwe Ntsimango,
• Kennedy J. Ngwira,
• Moira L. Bode and
• Charles B. de Koning

Beilstein J. Org. Chem. 2021, 17, 2340–2347, doi:10.3762/bjoc.17.152

• , such as ionic liquid- and transition metal-catalyzed and other metal-free transformations [1]. A strategically diverse route to phenanthridines involves intramolecular cyclization of biaryl oximes, allowing for the formation of a new C–N bond. Such a strategy was explored by Deb and Yoshikai in the Fe

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• -2), N-fluorobenzenesulfonimide (NFSI), and N-fluoro-2,6-dichloropyridinium tetrafluoroborate (5-4s) (Scheme 71) [99]. These reactions produced F-pClBzQN-X 31-2 quantitatively at 20 °C within 30 min in acetonitrile or in an ionic liquid such as 1-hexyl-3-methylimidazolinium hexafluorophosphate [hmim

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• subsequent elimination of HBr leads to the triazole ring [39]. Another metal-free strategy to 1,4,5-trisubstituted 1,2,3-triazoles 8 was realized by regioselective reaction of aryl azides 7 with enaminones 6 in the presence of triethylamine, water, and ionic liquid (IL). This method exhibits good functional

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

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

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

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• were mediated by acids and an ionic liquid. 3-Bromo-2,2-difluoropropyl ketones 114 were formed in good to excellent yields by an overall addition of HBr accompanied by a distal bond cleavage. Dolbier et al. also studied the MgI2-facilitated reactions of aryl-2,2-difluorocyclopropyl ketones 113 with

A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles

• Bingbing Lai,
• Meng Ye,
• Ping Liu,
• Minghao Li,
• Rongxian Bai and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238

• recyclability. However, the stability and durability of LS was very limited especially in polar solvents such as H2O, EtOH and at harsh conditions. In a further study of our previous work [15], a LS/dicationic ionic liquid composite was prepared via an ion exchange process, and then used as catalyst support for

A new method for the synthesis of diamantane by hydroisomerization of binor-S on treatment with sulfuric acid

• Rishat I. Aminov and
• Ravil I. Khusnutdinov

Beilstein J. Org. Chem. 2020, 16, 2534–2539, doi:10.3762/bjoc.16.205

• is replaced by an ionic liquid prepared from triethylamine and sulfuric acid [15], the reaction follows a different route: Starting binor-S (2) is converted to two isomeric hexacyclic hydrocarbons, hexacyclo[8.4.0.02,7.03,14.04,8.09,13]tetradec-5-ene (4а) and hexacyclo[6.6.0.0.2,6.05,14.07,12.09,13

Synergy between supported ionic liquid-like phases and immobilized palladium N-heterocyclic carbene–phosphine complexes for the Negishi reaction under flow conditions

• Edgar Peris,
• Raúl Porcar,
• María Macia,
• Jesús Alcázar,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2020, 16, 1924–1935, doi:10.3762/bjoc.16.159

• cross-coupling; NHC complex; palladium; supported ionic liquid; Introduction N-heterocyclic carbenes (NHCs) are known as efficient coordination ligands for different types of metals. The main feature of NHC complexes is their structural tunability [1]. Thus, their catalytic efficiency can be easily

• this leaching process, the role of the ligand and the support on the evolution of the catalytic systems should be carefully considered. It has been shown that the immobilization of Pd-catalysts or precatalysts onto supported ionic liquid-like materials can facilitate the recapture by the support of the

• released active species at the end of the reaction, in what has been called a “boomerang” mechanism [16][17]. Here, we report our efforts aiming a rational development for Negishi catalysts based on NHC–Pd complexes in conjunction with supported ionic liquid-like phases to enhance their catalytic stability

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125