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

• unsymmetrical forms of these salts serve as effective electrophilic arylating reagents in various organic syntheses. The use of diaryliodoniums in C–C and carbon–heteroatom bond formations, particularly under metal-free conditions, has further enhanced the popularity of these reagents. In this review, we

• concentrate on various arylation reactions involving carbon and other heteroatoms, encompassing rearrangement reactions in the absence of any metal catalyst, and summarize advancements made in the last five years. Keywords: arylation reaction; diaryliodonium salts; electrophilic arylation reagent; metal-free

• arylation; rearrangement reaction; Introduction The chemistry of hypervalent iodine compounds is well-established and they are prevalent as oxidants and electrophilic reagents in organic conversions [1][2][3]. They have gained significant attention due to their high reactivity and ability to carry out

C–H Trifluoromethylthiolation of aldehyde hydrazones

• Victor Levet,
• Balu Ramesh,
• Congyang Wang and
• Tatiana Besset

Beilstein J. Org. Chem. 2024, 20, 2883–2890, doi:10.3762/bjoc.20.242

• transformation, experiments with different SCF3 sources were conducted. First, we hypothesized that trifluoromethylthiolated succinimide, which might be in situ generated from NBS and AgSCF3, could be the active species. When the reaction was carried out in the presence of this electrophilic source and 1a, no

Synthesis of pyrrole-fused dibenzoxazepine/dibenzothiazepine/triazolobenzodiazepine derivatives via isocyanide-based multicomponent reactions

• Marzieh Norouzi,
• Mohammad Taghi Nazeri,
• Ahmad Shaabani and
• Behrouz Notash

Beilstein J. Org. Chem. 2024, 20, 2870–2882, doi:10.3762/bjoc.20.241

• electrophilic sites simultaneously in their structure, these zwitterions are able to participate in various cyclization processes, especially for the synthesis of pyrroles [37][38][39][40]. For example, Li et al. developed a one-pot four-component reaction (4-CR) of malononitrile, aldehydes, and isocyanides

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• -O-trimethylsilyl-ʟ-rhamnopyranose (4b) with TMSI gave intermediate A containing an anomeric iodide. Electrophilic addition of rhamnosyl iodide A to one of the two imino groups of 13 gave intermediate B. Another electrophilic addition of n-propyl mercaptane to the second imino group afforded

Synthesis of tricarbonylated propargylamine and conversion to 2,5-disubstituted oxazole-4-carboxylates

• Kento Iwai,
• Akari Hikasa,
• Kotaro Yoshioka,
• Shinki Tani,
• Kazuto Umezu and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2024, 20, 2827–2833, doi:10.3762/bjoc.20.238

• -acylamine; oxazole; propargylamine; Introduction Propargylamine is an important motif in the synthesis of heterocyclic compounds [1][2][3][4] and drug discovery [5][6] due to its multifunctionality, which includes a basic and nucleophilic amino group, an electrophilic and dipolarophilic triple bond, and an

• derivative has been employed (Scheme 1) [13][14]. Recently, we have demonstrated that the central carbonyl group of DEMO is highly electrophilic, facilitating the nucleophilic addition of less reactive reagents such as acid amides [23][24][25][26]. When the reaction was conducted in the presence of acetic

• various nucleophiles. This is because the imino carbon atom of 2 is also highly electrophilic, similar to DEMO [23][24][25]. This method offers an advantage over conventional methods as the N-acyl group can be modified by altering the acid amide. In this study, lithium acetylides were employed as

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

• by these findings, we now explored difluoromethylation reactions with compounds bearing less nucleophilic functional groups. Ketones caught our particular attention as they contain a weak nucleophilic carbonyl oxygen adjacent to an electrophilic carbonyl carbon. Previous studies have focused on

Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light

• Francesco Gambuti,
• Jacopo Pizzorno,
• Chiara Lambruschini,
• Renata Riva and
• Lisa Moni

Beilstein J. Org. Chem. 2024, 20, 2722–2731, doi:10.3762/bjoc.20.230

• reacts with an isocyanide and an electron-rich aniline in a three-component Ugi-type reaction to give an α-aminoamidine. This compound might undergo an additional visible light-mediated oxidation to furnish a second iminium intermediate, which acts as electrophile in an intramolecular electrophilic

Synthesis of fluoroalkenes and fluoroenynes via cross-coupling reactions using novel multihalogenated vinyl ethers

• Yukiko Karuo,
• Keita Hirata,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2024, 20, 2691–2703, doi:10.3762/bjoc.20.226

• blocks. When using them as nucleophilic reagents [15][16][17][18][19][20], the reaction between anion species, such as fluorine-containing Horner–Wadsworth–Emmons reagents, and carbonyl compounds led to E-selective olefination (Scheme 1A) [15]. On the other hand, some reactions with electrophilic

• fluorine-containing building blocks have been developed [21][22][23][24][25]. Jubault and Poisson et al. reported SN2’ reactions of hydride or alcohols to electrophilic fluorine-containing alkenes gave the corresponding fluoroalkenes (Scheme 1B) [21]. In recent years, many fluorine-containing coupling

Computational design for enantioselective CO₂ capture: asymmetric frustrated Lewis pairs in epoxide transformations

• Maxime Ferrer,
• Iñigo Iribarren,
• Tim Renningholtz,
• Ibon Alkorta and
• Cristina Trujillo

Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224

• initial study, it can be concluded that the mechanism for our system proceeds according to mechanism two. The following simulations were performed on this conclusion. Regioselectivity PO exhibits two distinct electrophilic sites, which can be subject to nucleophilic attack (Figure 2B). Thus, the

• new intermediate (Min5) is stabilised, in which the oxygen of CO2 has attacked the electrophilic carbon of PO, and the oxygen atom of PO interacts with the LB. This mechanism is exclusive to phosphorus-containing FLPs, as nitrogen does not support this type of reactivity. Subsequently, the

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

• not increase the yield of pyridine 11 further (Table 2). Despite the numerous works in the field of peroxydisulfate oxidation, there is still no unified view of the reaction mechanism. Consequently, in [31], the assumption of an electrophilic substitution mechanism for the Elbs and Boyland–Sims

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• atomoxetine, metaxalone, and tadalafil. Mechanistically, thiophenol is oxidized at the anode to the corresponding radical by SET, then dimerizes into a disulfide, which is further oxidized into an intermediate cation radical, yielding a highly electrophilic species. Subsequently, a selective anisole attack

• =C bond in the Co–alkene complex, forming an intermediate alkyl radical, which is further anodically oxidized to produce an intermediate alkyl cation. Another indole molecule undergoes electrophilic alkylation by this intermediate, forming an indolyl cation, which upon deprotonation yields the final

Phenylseleno trifluoromethoxylation of alkenes

• Clément Delobel,
• Armen Panossian,
• Gilles Hanquet,
• Frédéric R. Leroux,
• Fabien Toulgoat and
• Thierry Billard

Beilstein J. Org. Chem. 2024, 20, 2434–2441, doi:10.3762/bjoc.20.207

• developed an electrophilic phenylseleno trifluoromethoxylation of alkenes, which leads to β-selenylated trifluoromethoxylated compounds or, upon subsequent reduction, to the trifluoromethoxylated ones. Keywords: DNTFB; electrophilic addition; fluorine; selenium; trifluoromethoxy; Introduction Due to the

• compounds from alkenes and DDPyOCF3, more precisely to α-trifluoromethoxylated, β-phenylselenylated compounds. Results and Discussion The electrophilic addition of phenylselenyl halides to alkenes to form a selenonium intermediate that can be intercepted by an external nucleophile is a well-known method to

• obtain 1,2-disubstituted compounds [72][73][74]. Therefore, the reaction of alkenes with electrophilic sources of phenylselenyl in presence of DDPyOCF3 as a nucleophilic source of the CF3O group was studied (Table 1). First, we started from the optimal conditions previously established for the

Homogeneous continuous flow nitration of O-methylisouronium sulfate and its optimization by kinetic modeling

• Jiapeng Guo,
• Weike Su and
• An Su

Beilstein J. Org. Chem. 2024, 20, 2408–2420, doi:10.3762/bjoc.20.205

• values of k0 at different temperatures, the activation energy for the electrophilic attack of NO2+ on the IO can be calculated by the Arrhenius equation: where R is the molar gas constant and T denotes the temperature in Kelvin, and Ea and A are the activation energy and pre-exponential factors for the

Evaluating the halogen bonding strength of a iodoloisoxazolium(III) salt

• Dominik L. Reinhard,
• Anna Schmidt,
• Marc Sons,
• Julian Wolf,
• Elric Engelage and
• Stefan M. Huber

Beilstein J. Org. Chem. 2024, 20, 2401–2407, doi:10.3762/bjoc.20.204

• in a Mannich reaction [4]. In 2018, our group showed in a proof-of-principle study [5] that the Lewis acid catalysis by DAI salts is based on halogen bonding (XB), an interaction between a Lewis base (XB acceptor) and an electrophilic halogen atom in the Lewis acid (XB donor) [6][7][8][9][10]. In

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• excellent enantioselectivities (89–98% ee) and low to moderate yields (48–72%). The homologation step proceeds via the stereoretentive 1,2-migration of the vinyl group from the tetracoordinated boron to the highly electrophilic carbon of the diazomethane, concerted with the elimination of the nitrogen

• transfer reagents; (iv) direct metal-free imine carbanion addition to electrophilic alkene. Class (i) underwent an evolution from catalysis by covalent interaction to chiral hydrogen-bonded catalysis, which allowed the expansion of the allyl component scope from simple allyl to substituted allyl groups

Improved deconvolution of natural products’ protein targets using diagnostic ions from chemical proteomics linkers

• Andreas Wiest and
• Pavel Kielkowski

Beilstein J. Org. Chem. 2024, 20, 2323–2341, doi:10.3762/bjoc.20.199

• /off-target protein and a tested NP or a similar active small compound (Figure 1). The covalent bond serving this purpose can be formed in two distinct ways: either the NP or small compound already contains a reactive, often electrophilic group directly or the reactive group, for example a photo

Hydrogen-bond activation enables aziridination of unactivated olefins with simple iminoiodinanes

• Phong Thai,
• Lauv Patel,
• Diyasha Manna and
• David C. Powers

Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197

• general, transition metal catalysts are required to effect efficient NGT to unactivated olefins because iminoiodinanes are insufficiently electrophilic to engage in direct aziridination chemistry. Here, we demonstrate that 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) activates N-arylsulfonamide-derived

gem-Difluorination of carbon–carbon triple bonds using Brønsted acid/Bu₄NBF₄ or electrogenerated acid

• Mizuki Yamaguchi,
• Hiroki Shimao,
• Kengo Hamasaki,
• Keiji Nishiwaki,
• Shigenori Kashimura and
• Kouichi Matsumoto

Beilstein J. Org. Chem. 2024, 20, 2261–2269, doi:10.3762/bjoc.20.194

• fluorinating reagents, such as diethylaminosulfur trifluoride (DAST), HF, CsF, and AgF has been established as a reliable method. Electrophilic fluorinating reagents, such as 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor), N-fluorobenzenesulfonimide, and

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

• with electrophiles, such as deuteration or electrophilic chlorination using N-chlorosuccinimide, in this consecutive three-component synthesis to give persubstituted pyrazoles 165 (Scheme 55) [162]. (3 + 2)-Cycloaddition – C2 building blocks as substrates 1,3-Dipolar cycloadditions are important

Harnessing the versatility of hydrazones through electrosynthetic oxidative transformations

• Aurélie Claraz

Beilstein J. Org. Chem. 2024, 20, 1988–2004, doi:10.3762/bjoc.20.175

• generation of electrophilic thiocyanogen as the initial step. Further reaction with the hydrazone 95 and deprotonation led to hydrazonoyl thiocyanate intermediate 99, which isomerized to the thermodynamically more stable isothiocyanate derivatives 100 through 1,3-shift. The latter underwent spontaneous ring

• ) atom were well tolerated and the best result was obtained with a morpholine ring. Based on cyclic voltammetry studies, the transformation initiated with the anodic oxidation of hydrazone 101 to form highly electrophilic radical cationic species 104. Subsequent addition of azide 102 and desilylation

• species to be oxidized, initial SET anodic oxidation of the hydrazone furnishes the highly electrophilic radical cation species D, which undergo nucleophilic addition of the second partner and deprotonation to produce hydrazinyl radical F (route a). Alternatively, if the partner possesses a lower

Development of a flow photochemical process for a π-Lewis acidic metal-catalyzed cyclization/radical addition sequence: in situ-generated 2-benzopyrylium as photoredox catalyst and reactive intermediate

• Masahiro Terada,
• Zen Iwasaki,
• Ryohei Yazaki,
• Shigenobu Umemiya and
• Jun Kikuchi

Beilstein J. Org. Chem. 2024, 20, 1973–1980, doi:10.3762/bjoc.20.173

• Abstract A flow photochemical reaction system for a π-Lewis acidic metal-catalyzed cyclization/radical addition sequence was developed, which utilizes in situ-generated 2-benzopyrylium intermediates as the photoredox catalyst and electrophilic substrates. The key 2-benzopyrylium intermediates were

Radical reactivity of antiaromatic Ni(II) norcorroles with azo radical initiators

• Siham Asyiqin Shafie,
• Ryo Nozawa,
• Hideaki Takano and
• Hiroshi Shinokubo

Beilstein J. Org. Chem. 2024, 20, 1967–1972, doi:10.3762/bjoc.20.172

• through denitrogenation of AIBN, is closer to the HOMO level of Ni(II) norcorrole 1 (−4.68 eV) rather than its LUMO (−3.16 eV). This result explains the selective addition of the electrophilic isobutyronitrile radical to the distal α-position of the pyrrole unit. The calculated molecular orbital

• coefficient of the HOMO indicates that two α-carbon atoms of the pyrrole subunits are the most reactive positions for electrophilic species. In addition, the distal α-carbon atom relative to the meso-position could be more reactive than the proximal α-carbon atom due to the steric hindrance of bulky mesityl

• subsequent demetallation. Conclusion In conclusion, we have investigated the addition reaction of electrophilic alkyl radicals derived from azo radical initiators to antiaromatic Ni(II) norcorroles. The reaction smoothly proceeded to afford bowl-shaped nonconjugated macrocycles 2a in excellent yield, which

1,2-Difluoroethylene (HFO-1132): synthesis and chemistry

• Liubov V. Sokolenko,
• Taras M. Sokolenko and
• Yurii L. Yagupolskii

Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171

• 1,2-difluoroethylene (HFO-1132). The major routes for the preparation of the E- and Z-isomer of HFO-1132 are reviewed, along with the chemistry in radical, nucleophilic, and electrophilic reactions. Keywords: 1,2-difluoroethylene; fluorinated monomers; HFO-1132; hydrofluoroolefins; radical reactions

• ]. In this electrophilic reaction, two products were formed in 3:1 ratio (Scheme 17) in a very low yield of 0.4%. In patent literature [95], radical reaction of 1,2-difluoroethylene with long-chain perfluoroalkyl iodides (CnF2n + 1I, n = 2–8) was described (Scheme 18). Products formed were further

• transitional metal complexes with 1,2-difluoroethylene as a ligand should be mentioned [109][110][111]. Conclusion In conclusion, our literature analysis demonstrated that radical processes are most typical for 1,2-difluoroethylene, while examples of electrophilic reactions are scarce, and nucleophilic

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

• to be driven by stabilizing non-covalent interactions. Specifically, the carbonyl O in N2-s-cis shows NCIs with one of the benzene rings of PPh3 as well as a hydrogen bond-like NCI with a H-atom of the electrophilic methyl. Thus, the partitioning between transition states favor the N2-pathway over

• critically N1, position the electrophilic methyl group 2.1 Å from N2, lowering the TS energy by ΔΔG‡ = 2.6 kcal/mol in 18-N1-Cs. Interestingly, the difference in product energies is quite small, only favoring the N1-product, 18-N1, by 0.6 kcal/mol. Concerning conditions B, the difference between the neutral

• indazole and the deprotonated indazole was only −0.2 kcal/mol (Figure 11). Again, no preorganized intermediates were found. The NCIs were consistent with the parent system. The hydrogen bond between the H on the electrophilic methyl group and an ester oxygen was found in the transition state leading to the

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

• formed in oxidation. Since oxidation occurs in the bulk and the potential of the mediator is insufficient for the further oxidation of the electrophilic CF3-substituted diarylaminyl radicals to the corresponding cations, the N–N coupling of thus formed aminyl radicals dominates over the intramolecular