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

• of promoting the three-component cascade cyclization of 2-formylbenzonitriles, alkyl aryl ketones, and diaryliodonium salts to afford 2-arylisoindolinones 32 (Scheme 24) [41]. It is conceivable that the reaction starts with the formation of an N-arylnitrilium cation XXXI that, after hydrolysis

Direct trifluoroethylation of carbonyl sulfoxonium ylides using hypervalent iodine compounds

• Radell Echemendía,
• Carlee A. Montgomery,
• Fabio Cuzzucoli,
• Antonio C. B. Burtoloso and
• Graham K. Murphy

Beilstein J. Org. Chem. 2024, 20, 3182–3190, doi:10.3762/bjoc.20.263

• research groups recently reported the α-arylation between sulfoxonium ylides and diaryliodonium salts [33], and encouraged by this precedent, we envisioned that the chemistry between sulfoxonium ylides and hypervalent iodine compounds might be ripe for further exploitation. The trifluoroethyliodonium salt

• in 87% yield (Scheme 3b). To gain insight into the mechanism, we modelled two reaction pathways commonly suggested for the 2,2,2-trifuoroethyl(mesityl)iodonium triflate salt, and for related diaryliodonium salts (Figure 2). The first mechanism explored was the associative pathway that terminates via

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

• Ritu Mamgain Kokila Sakthivel Fateh V. Singh Department of Chemistry, SAS, Vellore Institute of Technology Chennai, Chennai-600 127, Tamil Nadu, India 10.3762/bjoc.20.243 Abstract Diaryliodonium salts have become widely recognized as arylating agents in the last two decades. Both, symmetrical and

• 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

• , diaryliodonium salts (DAIS), a versatile category of hypervalent iodine compounds, have seen significant progress in hypervalent iodine chemistry. Their efficiency and environmentally friendly characteristics have positioned DAIS as next-generation arylation reagents [29][30]. Other than aromatic electrophiles

Predicting bond dissociation energies of cyclic hypervalent halogen reagents using DFT calculations and graph attention network model

• Yingbo Shao,
• Zhiyuan Ren,
• Zhihui Han,
• Li Chen,
• Yao Li and
• Xiao-Song Xue

Beilstein J. Org. Chem. 2024, 20, 1444–1452, doi:10.3762/bjoc.20.127

• synthesized by Yoshida and Wencel-Delord (Figure 1). Cyclic hypervalent chlorine(III) reagents with similar skeletal structures have not been reported yet, and only biphenyl hypervalent chlorine(III) reagents [40][41][42] and cyclic diaryliodonium salts [43] have been synthesized. Previous investigations [44

A comparison of structure, bonding and non-covalent interactions of aryl halide and diarylhalonium halogen-bond donors

• Nicole Javaly,
• Theresa M. McCormick and
• David R. Stuart

Beilstein J. Org. Chem. 2024, 20, 1428–1435, doi:10.3762/bjoc.20.125

• (Scheme 1a) [1][2][3][4]. Hypervalent halogen compounds, specifically diaryliodonium salts, have also been known to form Lewis acid–base adducts [9][10] and a relative scale to quantify this property has recently been reported [11][12]. Consequently, there has been a recent surge in the use of

Ortho-ester-substituted diaryliodonium salts enabled regioselective arylocyclization of naphthols toward 3,4-benzocoumarins

• Ke Jiang,
• Cheng Pan,
• Limin Wang,
• Hao-Yang Wang and
• Jianwei Han

Beilstein J. Org. Chem. 2024, 20, 841–851, doi:10.3762/bjoc.20.76

• salts is an efficient tool for the construction of two or more chemical bonds in a one-pot process. Ortho-functionalized diaryliodonium salts have showcased distinct reactivity in the exploration of benzocyclization or arylocyclization. With this strategy of ortho-ester-substituted diaryliodonium salts

• , herein, we utilized a copper catalyst to activate the C–I bond of diaryliodonium salts in the generation of aryl radicals, thus resulting in an annulation reaction with naphthols and substituted phenols. This approach yielded a diverse array of 3,4-benzocoumarin derivatives bearing various substituents

• . Keywords: annulation; arylocyclization; 3,4-benzocoumarin; diaryliodonium salts; naphthol; Introduction Diaryliodonium salts as electrophilic reagents have attracted significant attention in the field of organic synthesis owing to their efficiency and selectivity [1][2][3][4][5][6][7]. Particularly, they

Synthesis of N-acyl carbazoles, phenoxazines and acridines from cyclic diaryliodonium salts

• Nils Clamor,
• Mattis Damrath,
• Thomas J. Kuczmera,
• Daniel Duvinage and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 12–16, doi:10.3762/bjoc.20.2

• diaryliodonium salts [29][31], as well as Pd-catalysed methods for synthesizing N-aryl carbazoles [32]. Similar procedures were published for the Cu-catalysed synthesis of aryl carbazoles from amines as well as other heterocycles such as N-acyl acridanes with nitriles using cyclic iodonium salts by Wen and Chen

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• -triazolines and their derivatives via tandem 1,2-addition/cyclization reactions between trifluoromethyl acylhydrazones and cyanamide [105] (Scheme 17b). Afterwards, Hu et al. developed a method for the N-arylation and N-alkylation of trifluoromethyl acylhydrazones with diaryliodonium salts and alkyl halides

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• (I-6, 0.042 e) and dichloroiodobenzene (I-7, 0.060 e) showed similar potentials with I-2 and I-3, with the weaker σ-hole found on the more covalent difluoroiodoarene species I-6 [72][87]. The symmetric diaryliodonium salts I-8 and I-9 each presented two σ-holes, with the acyclic variant’s potentials

• Liang also assessed the effect of ortho-substituents on iodonium ylides undergoing radiofluorination, similar to that encountered with diaryliodonium salts [135][136][137][138]. They prepared a series of ylides (61a–d) with substituents situated ortho- or para- to iodine, and found the radiochemical

• of diaryliodonium salts [136][140]. Incorporation of a Lewis basic ether that could participate in secondary bonding with iodine was critical, and further improvements were realized when this Lewis base was not deactivating the ring (62c vs 62d). From these examples, the evidence suggests that σ

Copper-catalyzed N-arylation of amines with aryliodonium ylides in water

• Kasturi U. Nabar,
• Bhalchandra M. Bhanage and
• Sudam G. Dawande

Beilstein J. Org. Chem. 2023, 19, 1008–1014, doi:10.3762/bjoc.19.76

• types of hypervalent iodine reagents, diaryliodonium salts are commonly used reagents for the N-arylation of nitrogen-containing compounds, particularly for N-arylation of amines under catalyst-free conditions either in the presence of additives or at higher temperatures [26][27][28][29][30][31][32

• ]. Further, a few reports are also available for the copper and palladium-catalyzed N-arylation of primary and secondary aliphatic as well as aromatic amines using diaryliodonium salts as aryl sources [33][34][35] (Scheme 1a). Similarly, iodonium ylides undergo a wide range of reactions through in situ

Synthesis and reactivity of azole-based iodazinium salts

• Thomas J. Kuczmera,
• Annalena Dietz,
• Andreas Boelke and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27

• highly versatile, and a wide range of applications is meanwhile established in organic synthesis [1][2][3][4][5]. They can be applied as mild oxidants [6][7][8], in phenol dearomatizations [9] or in α-oxygenation reactions [10]. In a complemental reactivity, diaryliodonium salts are potent electrophilic

Two-step continuous-flow synthesis of 6-membered cyclic iodonium salts via anodic oxidation

• Julian Spils,
• Thomas Wirth and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 27–32, doi:10.3762/bjoc.19.2

• continuous-flow procedure for the generation of six-membered diaryliodonium salts. The accompanying scalability and atom economy are significant improvements to existing batch methods. Benzyl acetates are submitted to this two-step procedure as highly available and cheap starting materials. An acid-catalyzed

• blocks for the synthesis of natural products [16][17][18][19][20][21]. One subclass of HVIs is diaryliodonium salts (DIS), which have been used as versatile electrophilic arylation reagents in metal-catalyzed and metal-free reactions [22][23]. The corresponding cyclic diaryliodonium salts (CDIS) have

• . Conclusion In summary, we have developed the first multi-step continuous-flow procedure for the generation of cyclic six-membered diaryliodonium salts. Starting from easily accessible benzyl acetates we were able to combine a Friedel–Crafts alkylation with a subsequent anodic oxidative cyclization in flow

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

• Tülay Yıldız,
• İrem Baştaş and
• Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

• alcohols with diaryliodonium salts [26], the Sc(OTf)3-catalyzed domino reaction [27], and the iodine-catalyzed nucleophilic substitution reaction of xanthen-9-ol [28]. As an example of an intramolecular hydroarylation of an olefin, 9,10-dihydroacridines, which are N derivatives of xanthenes, were

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• solvent (Scheme 57). The complex is bound together by weak halogen bonds, in which phosphorus lone-pair electrons interact with σ* orbitals of C–I bonds. A variety of arylphosphonates can be directly afforded by the simple combination of diaryliodonium salts and phosphite esters. In addition, calculations

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

• 2012 the possibility to extend this C–H activation/photoredox dual catalytic system by using diaryliodonium salts as radical precursors [83]. Considering the higher reduction potentials of these compounds in comparison with the corresponding diazoniums, a stronger reductive iridium-based photocatalyst

Copper-based fluorinated reagents for the synthesis of CF₂R-containing molecules (R ≠ F)

• Louise Ruyet and
• Tatiana Besset

Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92

• was illustrated through the 1,1-difluoroethylation of diaryliodonium salts, leading to the corresponding (1,1-difluoroethyl)arenes in moderate to high yields (Scheme 13). The transformation turned out to be functional group tolerant and even heteroaromatic compounds were functionalized. Copper-based

• (diethylphosphono)difluoromethylthiolated molecules via the in situ generation of CuCF2PO(OEt)2 species. Synthesis of (phenylsulfonyl)difluoromethyl-containing molecules via the in situ generation of CuCF2SO2Ph species. Copper-mediated 1,1-difluoroethylation of diaryliodonium salts by using the in situ-generated

Copper-catalyzed O-alkenylation of phosphonates

• Nuria Vázquez-Galiñanes,
• Mariña Andón-Rodríguez,
• Patricia Gómez-Roibás and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2020, 16, 611–615, doi:10.3762/bjoc.16.56

• Feringa recently reported a catalytic method for the synthesis of mixed alkyl aryl phosphonates based on a copper-catalyzed arylation of phosphonates with diaryliodonium salts [32]. Encouraged by this work, in the context of an electrophilic alkenylation of phosphonates, we reasoned that the action of a

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• can deliver the product through a reductive elimination, along with the [Cu(I)] species in the ground state. 1.2 Reduction reactions In 2013, Fensterbank, Goddard, and Ollivier reported the use of the homoleptic complex [Cu(I)(dpp)2]PF6 for the reduction of symmetrical diaryliodonium salts (Scheme 8

• isolated in moderate to good yields. Using the more reactive allyl sulfone, a panel of symmetrical diaryliodonium salts was reacted, giving the products in good yields. The authors conducted some mechanistic studies and suggested a plausible catalytic cycle involving [Cu(I)]/[Cu(I)]*/[Cu(II)] species. The

• haloperfluoroalkylation of alkenes and alkynes. Chlorosulfonylation of alkenes catalyzed by [Cu(I)(dap)2]Cl. aNo Na2CO3 was added. b1 equiv of Na2CO3 was used. Copper-photocatalyzed reductive allylation of diaryliodonium salts. Copper-photocatalyzed azidomethoxylation of olefins. Benzylic azidation initiated by [Cu(I

Thermal stability of N-heterocycle-stabilized iodanes – a systematic investigation

• Andreas Boelke,
• Yulia A. Vlasenko,
• Mekhman S. Yusubov,
• Boris J. Nachtsheim and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2019, 15, 2311–2318, doi:10.3762/bjoc.15.223

• analysis. Initially, the thermal decomposition of pseudocyclic diaryliodonium salts 18 and 19 was measured. For both salts, initial endothermic melting was followed by exothermal decomposition (Supporting Information File 1 and Figure 6). Compared to hydroxy(phenyl)-λ3-iodanes 1 and 2, the pseudocyclic

• diaryliodonium salts 18 and 19 show a significantly decreased ΔHdec from 72.9 kJ/mol to 10.2 kJ/mol for benziodoxolones 1 and 18 and from 116.3 kJ/mol to 23.4 kJ/mol for the triazole derivatives 2 and 19. The same trend of a higher thermal stability and lower ΔHdec for diaryliodonium salts compared the their

• hydroxy-substituted congeners can be observed for all other pseudocyclic N-heterocycle-substituted derivatives 20–29. Pyrazole 24 is the only exception. All investigated diaryliodonium salts can be defined as safe due to Tpeak values of usually above 180 °C and ΔHdec values of less than 50 kJ/mol. A

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• ] presented the nucleophilic fluorination of diaryliodonium salts with KF through a Cu(I/III) catalytic cycle mechanism. This procedure preferentially fluorinates the smaller aromatic ligand on iodine(III). Also, the addition of Cu(OTf)2 and 18-crown-6 promoted the fluorination effectively. Finally, excellent

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• contributions aromatic aldehyde, imine or nitrile compounds have been used instead. For instance, 2-formylbenzonitriles 85 along with a variety of arenes 86 and diaryliodonium salts 87, combined in a copper-catalysed three-component cyclization produce 2,3-diarylisoindolinones 88 [103] (Scheme 25). The scope of

• the reaction is very wide, since the three components have demonstrated the ability to be efficient sources of diversity in this reaction. Indeed, 33 isoindolinones 88 were prepared with yields ranging from moderate to very good. Even when unsymmetrical diaryliodonium salts 87 were used, the reaction

• reaction of trimethylsilylaryltriflates 77, isocyanides 42 and CO2 (78). Plausible mechanism for the three-component synthesis of phthalimides 79. Copper-catalysed three-component reaction of 2-formylbenzonitriles 85, arenes 86 and diaryliodonium salts 87. Copper-catalysed three-component reaction of 2

DFT calculations on the mechanism of copper-catalysed tandem arylation–cyclisation reactions of alkynes and diaryliodonium salts

• Tamás Károly Stenczel,
• Ádám Sinai,
• Zoltán Novák and
• András Stirling

Beilstein J. Org. Chem. 2018, 14, 1743–1749, doi:10.3762/bjoc.14.148

• explain our computational strategy and discuss the possible reaction paths leading to the formation of 5-(diphenylmethylene)-4,5-dihydrooxazole in the reaction of propargylic amides and diaryliodonium salts in the presence of a Cu(I) catalyst. This is a simplified model of the original reaction scheme [44

• –ring closure reaction of alkynyl substrates with diaryliodonium salts can be depicted as follows: first the Cu(III)–aryl electrophile forms an intermediate with the triple bond of the reactant, then the aryl moiety migrates to the activated triple bond which is followed by a fast ring-closing step. The

• stereoselectivity of the reaction and it also excludes the formation of vinyl-cation intermediates. The obtained results could serve as a useful and more general description of the mechanism of the carboarylation–ring closure strategy based on the utilisation of alkynes and diaryliodonium salts, beyond the selected

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• and migratory addition into the proximal alkyne. Transmetalation of the vinylpalladium with the boronic acid and reductive elimination finally leads to alkylidenefluorenes 49. This multicomponent strategy allows the variation of the alkyne, the boronic acid and the diaryliodonium salts, but the use of

Metal-free formal synthesis of phenoxazine

• Gabriella Kervefors,
• Antonia Becker,
• Chandan Dey and
• Berit Olofsson

Beilstein J. Org. Chem. 2018, 14, 1491–1497, doi:10.3762/bjoc.14.126

• -arylations of phenols using diaryliodonium salts [23][24][25], which are reactive electrophilic arylation reagents [26][27][28]. As diaryliodonium salts can be easily synthesized in a one-pot manner [28], we envisioned that phenoxazines could be obtained in a straightforward and efficient manner from

• sequence, proceeding via arylation of phenols with diaryliodonium salts using our reported methodology [23][24][25]. In reactions with unsymmetrical iodonium salts, this type of O-arylation is known to have an ortho-effect, i.e., chemoselective transfer of the ortho-substituted aryl moiety [29][30]. The

• diaryliodonium salts proceeds at room temperature [31][32]. Results and Discussion We initially focused on route A and decided to explore an anisyl moiety as dummy group in iodonium salt 5. The electronic difference between the aryl groups in the formed salt should be sufficient to allow chemoselective transfer

Atom-economical group-transfer reactions with hypervalent iodine compounds

• Andreas Boelke,
• Peter Finkbeiner and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2018, 14, 1263–1280, doi:10.3762/bjoc.14.108

• partner) are taken into account. Other additives, such as additional bases, acids or catalysts were neglected. Review 1. Diaryliodonium salts 1.1. Acyclic diaryliodonium salts Acyclic diaryliodonium salts 1 find widespread application in numerous metal-free and transition metal-mediated electrophilic

• ]. Here, symmetrical diaryliodonium salts 1 were used in a palladium-catalysed cross-coupling reaction with sodium tetraphenylborate (Scheme 3). This reaction not only provides excellent yields of the respective biphenyls 3 but also exhibits a high AE (57% for Ar = Ph). However, its general synthetic

• utility is limited since it requires highly reactive boron compounds as nucleophiles. Symmetrical biphenyls 3’ can be generated from the corresponding symmetrically substituted diaryliodonium salts 1 and bis(pinacolato)diboron as demonstrated by Muñiz and co-workers [25]. In the first step, a mild carbon