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

• these conditions the reaction between aryl thiosulfonates with arynes to give sulfones is competitive. Cu(OTf)2 is essential to remove the sulfinate anions in the reaction medium, avoiding side reactions arising from their attack to the electrophilic arynes. The so-obtained products are susceptible of

Reactivity of hypervalent iodine(III) reagents bearing a benzylamine with sulfenate salts

• Beatriz Dedeiras,
• Catarina S. Caldeira,
• José C. Cunha,
• Clara S. B. Gomes and
• M. Manuel B. Marques

Beilstein J. Org. Chem. 2024, 20, 3281–3289, doi:10.3762/bjoc.20.272

• reactivity with in situ-generated sulfenate anions, from β-sulfinyl esters, to achieve S–N bond formation. The importance of establishing this S–N bond results from the widespread presence of sulfonyl-containing bioactive compounds, such as the sulfonamide group which can be found in many pharmaceuticals

• 5aa (Table 1, entry 2) but with prior degassed solvent (DMF), to prevent potential oxidation of the sulfenate to sulfinate anions. Indeed, the oxidation of the unstable sulfenate intermediates has been previously reported by Waser when using EBX – an HIR applied in the transfer of alkynes to sulfenate

Surprising acidity for the methylene of 1,3-indenocorannulenes?

• Shi Liu,
• Märt Lõkov,
• Sofja Tshepelevitsh,
• Ivo Leito,
• Kim K. Baldridge and
• Jay S. Siegel

Beilstein J. Org. Chem. 2024, 20, 3144–3150, doi:10.3762/bjoc.20.260

• compounds tend to deprotonate to form highly stable anions. The air stability of TBF conforms to that model. In contrast, although the dianion of BFC can be generated with tert-butoxide under inert atmosphere, in the presence of water it quenches and exposed to oxygen it oxidizes to form the diketone

• pentabenzocorannulene would produce air-stable radical and ionic PAHs, and that coupling such fragments would lead to stable redox-active carbon sheets. Conclusion In conclusion, the “surprise” in the surprising pKa for BIC and FIC was in our expectation of the deprotonated forms as poorly delocalized fluorenyl anions

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• metal-free porphyrins. 1.1 Calix[4]pyrrole macrocycles as organocatalysts Calix[4]pyrroles act as versatile ligands in supramolecular chemistry and have been widely studied as binding hosts for various guests such as anions, ion pairs, or neutral compounds [4][30][31], ligands for p-block elements, as

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

• Anastasia I. Ershova,
• Sergey V. Fedoseev,
• Konstantin V. Lipin,
• Mikhail Yu. Ievlev,
• Oleg E. Nasakin and
• Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

• ], positron emission tomography (PET) imaging [24], fluorescent probes and labels [25][26][27] detecting H2S in foodstuff, water, and living cells [28], Fe3+ ions [29], Hg2+ ions [30], and cyanide anions [31], for acid–base vapor sensing [32], and as candidate material for photonics devices, optical switches

Tailored charge-neutral self-assembled L₂Zn₂ container for taming oxalate

• David Ocklenburg and
• David Van Craen

Beilstein J. Org. Chem. 2024, 20, 3007–3015, doi:10.3762/bjoc.20.250

• ; metallocontainer; oxalate; Introduction Dicarboxylic acids and their corresponding anions are essential intermediates in the biosynthesis of proteins and important biological metabolites [1][2]. As a result, the development of receptors for this class of compounds is of high interest [3][4][5]. Oxalate, the

• metallocontainers which are formed by metal-driven self-assembly have become especially popular to bind various kinds of anions since such systems offer easy to tune confinements. Usually, the utilized complexes are net positive which makes them ideal hosts for anions [56][57][58][59][60][61][62][63]. However, the

• positively charged or charge-neutral, is their metal-driven self-assembly. Unfortunately, this can also be their Achilles' heel, as the underlying coordination bonds are fragile compared to covalent bonds. For example, metallocages can easily break apart by the addition of competitive anions which are highly

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• nature of X− [45][46]. Anions like tetrafluoroborate, hexafluorophosphate, and trifluoromethanesulfate are commonly used in DAIS due to their good solubility and weak nucleophilicity. If the two aryl groups (Ar1 and Ar2) in DAIS are different, they are termed unsymmetric diaryliodonium salts 3. The

• diaryliodonium salts regardless of their differing counter-anions. A range of 2-naphthol substrates, including those bearing alkyl and aryl groups, halogens, trimethylsilyl, and protected hydroxy at positions 6 and 7, exhibited good tolerance. However, the reaction with 1-naphthol did not yield positive results

• diaryliodonium salts. Recent advancements in this field have focused on the development of practically simple and scalable methods for the arylation of oxygen using diaryliodonium salts. By modifying the counter anions attached to the iodonium ion, the stability and reactivity of new symmetrical and

Investigation of a bimetallic terbium(III)/copper(II) chemosensor for the detection of aqueous hydrogen sulfide

• Parvathy Mini,
• Michael R. Grace,
• Genevieve H. Dennison and
• Kellie L. Tuck

Beilstein J. Org. Chem. 2024, 20, 2818–2826, doi:10.3762/bjoc.20.237

• removal of Na2S followed by the precipitation and re-addition of Cu2+ ions (Figure 5). Comprehensive selectivity studies were conducted with various anions/sulfur compounds (SO42−, SO32−, S2O52−, S2O42−, S2O32−, ClO−, OAc−, NO3−, I−, HCO3−, CO32−, Cl−, lipoic acid, and glutathione, as depicted in Figure 6

• are highly selective to HS−(aq) ions and are thus suitable for environmental or biological studies where interfering anions may be present. Gaseous H2S studies of [Tb.1·3Cu]3+ We aimed to further investigate the luminescence response of Tb3+ analogues upon exposure to hydrogen sulfide gas, building

• ), was incrementally spiked with a standard solution of 1 mM Na2S(aq). The time-gated luminescence emission spectrum (λex = 250 nm) of the solution was recorded after each addition. Competition assay with anions and cations: The time-gated luminescence emission change of a solution of [Tb.1·3Cu]3+ (5 μM

Mechanochemical difluoromethylations of ketones

• Jinbo Ke,
• Pit van Bonn and
• Carsten Bolm

Beilstein J. Org. Chem. 2024, 20, 2799–2805, doi:10.3762/bjoc.20.235

• reactions of difluorocarbene with cyclic and acyclic 1,3-diones (Scheme 1A) [41][42][43][44][45]. Typically, they were conducted with a base to form the corresponding enolate anions which then reacted with difluorocarbene to yield difluoromethyl enol ethers. Those products are of interest because they

C–C Coupling in sterically demanding porphyrin environments

• Liam Cribbin,
• Brendan Twamley,
• Nicolae Buga,
• John E. O’ Brien,
• Raphael Bühler,
• Roland A. Fischer and
• Mathias O. Senge

Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234

• alternatively by core protonation, whereby all four-core nitrogen atoms are protonated to produce the diacid [12][13]; these diacids can tilt the pyrrole rings 20–40° [14] from the mean-porphyrin plane. Norvaiša et al. showed that a saddle-shaped porphyrin as a dodecasubstituted diacid can bind anions via two

• independent faces and trap anions such as pyrophosphate [15]. Saddle-shaped porphyrins have also been exploited by researchers for the use in organocatalysis as bifunctional system [16][17]. Dodecasubstitution of porphyrin, as seen in Figure 1, often results in saddle-shaped distortion; however, ruffled [18

Efficient modification of peroxydisulfate oxidation reactions of nitrogen-containing heterocycles 6-methyluracil and pyridine

• Alfiya R. Gimadieva,
• Yuliya Z. Khazimullina,
• Aigiza A. Gilimkhanova and
• Akhat G. Mustafin

Beilstein J. Org. Chem. 2024, 20, 2599–2607, doi:10.3762/bjoc.20.219

• generate sulfate anion radicals (SO4•−) [42] during their interaction with sulfate anions. This reaction occurs at a significant rate (k = 3.1∙108 min−1) [43] and leads to the recombination of peroxydisulfate in the reaction mixture. It has been demonstrated that the efficiency of peroxydisulfate

Anion-dependent ion-pairing assemblies of triazatriangulenium cation that interferes with stacking structures

• Yohei Haketa,
• Takuma Matsuda and
• Hiromitsu Maeda

Beilstein J. Org. Chem. 2024, 20, 2567–2576, doi:10.3762/bjoc.20.215

• ] formed a charge-by-charge assembled structure, with alternate stacking of TATA+ and PCCp− through iπ–iπ interactions in the crystal state [20][21]. Charge-by-charge stacking assemblies of 1a+ and porphyrin-based π-electronic anions showed the crystal-state PET between proximally located anions and

• cations [21]. Moreover, ion-pairing assemblies of 1a+ and the π-electronic receptor–anion complexes as pseudo-π-electronic anions exhibited electric conductive properties [22][23][24][25]. The structures and electronic states of ions directly affect the arrangement of constituent ions in the assemblies

• PF6− anions located above the TATA+ plane (Figure 3b,c and Figure 5b,c). Three of the fluorine atoms of BF4− and PF6− were pointed toward the TATA+ plane. The offset angles for Cl−, BF4−, and PF6− to the TATA+ central carbon were 87.7°, 78.1°, and 84.3°, respectively. The distances between fluorine

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• of a variety of biologically important anions due to the presence of two pyrrolic NH hydrogen bond donors [38][39][40][41][42][43]. Notably, in the past few decades, the chemistry of DPMs have attested to be imperative in the existing chemical research because of their easy syntheses, good stability

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

• Akiya Ogawa and
• Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

• radical; isocyanide; radical addition; radical cyclization; Introduction Carbon monoxide is a very important C1 resource in both synthetic and industrial chemistry and is not only capable of reacting with a variety of active species such as carbon cations, carbon anions, and carbon radicals (Figure 1

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

• Pengcheng Lu,
• Luis Juarez,
• Paul A. Wiget,
• Weihe Zhang,
• Krishnan Raman and
• Pravin L. Kotian

Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170

• negligible. These data suggest that deprotonation occurs prior to alkylation and that deprotonation of either indazole tautomer leads to anions of identical or highly similar energy. Furthermore, as seen in Figure 4, a total, five coordinated complexes were found to be at least 4.5 kcal/mol more stable than

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

• A1–A3 and N-arylpyridoindazoliums S1–S3 can be presented in the following scheme (Scheme 3). Anions formed after two-electron reduction of N-arylpyridoindazolium salts are strong bases and can be considered as electrogenerated proton sponges. That was demonstrated taken salt S3 as an example

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

• have been used to effect the transformation of benzylic C(sp3)–H to C(sp3)–F bonds [22]. Shreeve and co-workers reported the use of KOH or n-BuLi to deprotonate acidic protons at benzylic positions adjacent to electron-withdrawing nitro or nitrile groups, respectively, generating benzylic anions that

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• triggered to carry out energy transfer and electron transfer or proton-coupled electron transfer when it absorbs light of an appropriate wavelength (Figure 2). These processes generate highly reactive species, such as radical cations or anions, which can initiate the desired organic transformations

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

• the additional electron transfer to form the corresponding anions is a highly favorable pathway due to the more positive reduction potential of radicals than that of the starting halides [38], employing redox mediators enables the generated aryl radicals to participate in radical arylation reactions

• presence of H2O and 5 mol % of 1,3-dicyanobenzene (1,3-DCB) [55] under visible-light irradiation at 0 °C (Table 1, entry 1) [56]. Ammonium salts containing other counter anions also afforded 3aa in slightly lower yields (Table 1, entries 2 and 3). Changing the sacrificial anode or cathode did not improve

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

• weakly coordinating anions like bis(trifluoromethylsulfonyl)imide [NTf2]− [25]. In addition, dicationic salts or anions containing metal complexes have been described [26][27]. Due to the numerous combinations of different anions and cations, ILs can also be described as designer solvents [28]. We

• different alkyl chain lengths and bromide as well as NTf2 anions. The physicochemical properties (thermal properties, viscosity, conductivity and electrochemical window) of the RTILs were investigated. The two methyl groups in the backbone of the imidazolium core lead to a slightly higher viscosity compared

Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria

• Kara A. Strickland,
• Brenda Martinez Rodriguez,
• Ashley A. Holland,
• Shelby Wagner,
• Michelle Luna-Alva,
• David E. Graham and
• Jonathan D. Caranto

Beilstein J. Org. Chem. 2024, 20, 830–840, doi:10.3762/bjoc.20.75

• (160 μM), Ms (38 μM), and Ps (28 μM). Representative LC–MS EICs monitoring molecular anions of NNG (m/z 119.01 ± 100 ppm) and glyoxylate (m/z 72.99 ± 100 ppm) in samples containing 350 μM NNG, 10 μM dithionite, and 5 μM of indicated NnlA homolog. Samples were incubated for approximately one hour at 21

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• − anions to the open form unexpectedly resulted in the closing of the tweezers thanks to a Mn–CN–Mn bridging [45]. An antiferromagnetic coupling between the two Mn(III) centers combined with a spin crossover from high spin to low spin Mn(III) was observed. Like in the other terpy-based tweezers, a

• counter ions, the bis(terpy) complex is exclusively formed in CDCl3/CD3OD 4:1. This complex can be converted to the 1:1 species upon exchange of the triflate with more coordinating chloride anions or directly formed upon closing with ZnCl2. Interestingly, only the closed 1:1 form presents a selective

• ). They developed tweezers with carboxamidoindole units connected in 4 and 4’ positions to a 2,2’-bipyridine unit for switchable anion recognition [62]. The uncomplexed open conformation displays a very low affinity for anions such as chloride, acetate, or diphosphate (log K < 2). The coordination of

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• -centered while being C-centered in analogous anions alpha to sulfonamides [51]. Sulfonamides are known to protonate at nitrogen [31]. Gold coordination to carbonyls would be predicted to retain N-centered nucleophilicity, while gold coordination to the sulfonamide nitrogen would not. Sulfonamides are less

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

• fragmentation rate constants or the N–O bond dissociation energies of radical anions and neutral radicals derived from RAEs are not available in the literature. Lumb and co-workers recently published a study on the conversion of biaryl-derived NHPI esters into spirocyclic cyclohexadienones through a