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

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

Discovery of unguisin J, a new cyclic peptide from Aspergillus heteromorphus CBS 117.55, and phylogeny-based bioinformatic analysis of UngA NRPS domains

• Sharmila Neupane,
• Marcelo Rodrigues de Amorim and
• Elizabeth Skellam

Beilstein J. Org. Chem. 2024, 20, 321–330, doi:10.3762/bjoc.20.32

• small peptides [3][4][9], however, unguisin A has been shown to bind a series of anions [10]. Recently the biosynthesis of unguisins A and B from Aspergillus violaceofuscus CBS 115571 was reported [5]. A seven module non-ribosomal peptide synthetase (NRPS; UngA) was heterologously expressed in

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• ). In this case, the participation of the acenaphthylene derivative seems quite logical, since this should facilitate the SNAr reaction and inhibit the formation of type 7 anions (under the action of methoxide as a base), which are inactive to subsequent nucleophilic attack. Dimethoxyacenaphthylene 14

• acenaphthylene 8) or as a result of double protodebromination (giving acenaphthene 5). Overall, the observed process resembles a redox transformation. Benzyl-type anions, which have hydride mobility and are formed in an alkaline environment from 15, may act as a reducing agent here. We tried to stop this

• increase in the series 3 → 5 → 8 (“clothespin” effect) [30]. The crystal packing patterns in salts 5·HBF4 and 8·HBF4 are quite similar. The main factor here continues to be the tendency of almost flat disk-shaped heterocyclic cations to π-stacking, leading to the formation of dense columns with anions in

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• + cations (500 equiv). At the same time, addition of TBA+ cations showed just a minimal impact on the stability of the Z-form comparable with the effect of counter anions and solvent polarity. In 2021, Tsubaki and co-workers synthesized bridged N,N′-dialkyl-substituted indigos 13 and studied their thermal

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

• weakly coordinating or not-coordinating organic or inorganic anions. They have interesting physicochemical properties that differentiate them from the organic solvents commonly used in synthesis [74][75][76][77]. Importantly, they have a very low vapour pressure, and therefore do not behave as air

• experiments were carried out under the conditions reported in entry 9 of Table 1, in order to observe possible variations in the yield of compound 2a. ILs with different anions or cations (compared to BMIm-BF4) were investigated to probe potential interactions with the reagents, the intermediates or the

• 1-butyl-3-methylimidazolium cation unchanged, anion variation also affected the reaction yield. Indeed, in the presence of triflate, acetate or trifluoroacetate anions the desired product was obtained only in trace amounts (Table 3, entries 10–12). This could be explained by the fact that these

Anion–π catalysis on carbon allotropes

• M. Ángeles Gutiérrez López,
• Mei-Ling Tan,
• Giacomo Renno,
• Augustina Jozeliūnaitė,
• J. Jonathan Nué-Martinez,
• Javier Lopez-Andarias,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2023, 19, 1881–1894, doi:10.3762/bjoc.19.140

• –16 was as in the amide series from 8 and thus supported entropic contributions to anion–π catalysis. Steric increase of the secondary amide in 17 impeded anion–π catalysis, presumably because the catalytic π surface next to the ammonium cation became inaccessible for anions paired with the tethered

• fullerenes as well. The unique polarizability of fullerene monomers like 1 is thought to induce strong anion–π interactions and thus account for the observed catalytic activity (Figure 7A) [12]. This polarizability should further increase in fullerene dimers like 36 [80]. Anions, anionic reactive

Controlling the reactivity of La@C₈₂ by reduction: reaction of the La@C₈₂ anion with alkyl halide with high regioselectivity

• Yutaka Maeda,
• Saeka Akita,
• Mitsuaki Suzuki,
• Michio Yamada,
• Takeshi Akasaka,
• Kaoru Kobayashi and
• Shigeru Nagase

Beilstein J. Org. Chem. 2023, 19, 1858–1866, doi:10.3762/bjoc.19.138

• , the third carbon allotrope, have unique spherical molecular structures and exhibit high reactivity as electron-deficient polyolefins. The excellent redox properties of fullerenes are useful for their chemical derivatization and practical applications [1][2][3][4][5]. Fullerene anions can be easily

• added to the solution to precipitate excess TBAF which was then removed by filtration. The La@C2v-C82 anion ([La@C2v-C82]PF6) was collected as the filtrate (with a 78% yield estimated from the molar absorbance coefficient). This step was repeated to ensure a sufficient amount of La@C2v-C82 anions for

• @C2v-C82 anion with 1a. 110 °C, 2 h. (b) La@C2v-C82 with 1a. 110 °C, 2 h. (c) La@C2v-C82 anion with 1a. hv > 350 nm, 1 h. (d) La@C2v-C82 with 1a. hv > 350 nm, 1 h. Black line is the HPLC profiles of La@C2V-C82 at the same concentration as the reaction. Reaction mixtures with La@C2v-C82 anions were

Unprecedented synthesis of a 14-membered hexaazamacrocycle

• Anastasia A. Fesenko and
• Anatoly D. Shutalev

Beilstein J. Org. Chem. 2023, 19, 1728–1740, doi:10.3762/bjoc.19.126

• [1][2][3][4][5][6]. The great interest in PAMs is primarily due to their ability to bind various cations, anions, and neutral molecules [7][8][9][10][11][12][13][14]. In addition, some representatives of PAMs were found in various natural products and play an important role in living systems (e.g

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

• (located and refined for 1bH, geometrically placed for the others). Structures of the cations from the single crystal structures of 1g+I− (left), 1h+PF6− (center), and 1i+PF6− (right), shown with 50% thermal ellipsoids and excluding hydrogen atoms and counter anions. Cyclic voltammograms (50 mV s−1, THF

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• ]. The CsF binding led to a supramolecular self-assembly process, inducing a sandwich host–guest complex formation in the solid state (Scheme 2). It was established that fluoride is preferred over any other halide anions. The binding of the ion pairs was observed in highly polar solvent media, but in the