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

• -chloroperoxybenzoic acid (mCPBA) as the oxidant of choice in the presence of triflic acid (TfOH) [27][29]. Based on these promising results, the conditions were optimized using o-benzimidazole-substituted iodoarenes 4aa and 4ah (Table 1). While running the reaction in MeCN as solvent resulted in no product formation

• (Table 1, entry 8). Next, various substituted iodoarenes 4 were oxidized and cyclized using the optimized conditions to generate a diverse set of azoiodazinium salts 5 (Figure 2). The ortho-methylated salt 5ab was obtained in a low yield of 19%, and the fluorinated derivative 5ac could be obtained in 55

• electron-rich dimethylated benzimidazole, this moiety combined with the chlorinated and brominated iodoarene gave the corresponding salts 5at and 5au in good yields under milder reaction conditions, in particular in direct comparison to the unsubstituted analogs 5ah–aj. N-Substituted iodoarenes were then

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

• also been investigated as useful building blocks for the synthesis of larger diaryl-based molecules, (hetero)aromatic tricyclic systems, or new aryl-moieties [24][25]. Most methods that generate DIS utilize iodoarenes as starting materials [26][27]. In these one-pot procedures, iodoarenes react with

• , we improved the formation of iodoarenes through a Brønsted acid-mediated Friedel–Crafts reaction followed by an oxidative cyclization to form the desired CDIS 1 (Scheme 1A). This one-pot approach is based on ortho-iodinated benzyl alcohols as starting materials. It allows access to a variety of

• otherwise tedious to synthesize CDIS robustly in short reaction times. A significant drawback still is the use of stoichiometric amounts of chemical oxidants, which decreases the atom economy and necessitates additional workup procedures. A possible solution is the anodic oxidation of iodoarenes as

AlBr₃-Promoted stereoselective anti-hydroarylation of the acetylene bond in 3-arylpropynenitriles by electron-rich arenes: synthesis of 3,3-diarylpropenenitriles

• Yelizaveta Gorbunova,
• Dmitry S. Ryabukhin and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2663–2667, doi:10.3762/bjoc.17.180

• way for the synthesis of compounds 2. These compounds can be alternatively obtained by a Pd-catalyzed Heck reaction of 3-arylpropenenitriles with iodoarenes [23] or by a Cu-catalyzed hydroarylation of 3-arylpropynenitriles with arylboronic acid [24][25]. There is one example of use of dicyanoacetylene

Catalytic trifluoromethylation of iodoarenes by use of 2-trifluoromethylated benzimidazoline as trifluoromethylating reagent

• Tatsuhiro Uchikura,
• Nanami Kamiyama,
• Taisuke Ishikawa and
• Takahiko Akiyama

Beilstein J. Org. Chem. 2020, 16, 2442–2447, doi:10.3762/bjoc.16.198

• Tatsuhiro Uchikura Nanami Kamiyama Taisuke Ishikawa Takahiko Akiyama Department of Chemistry, Faculty of Science, Gakushuin University, Mejiro, Toshima-ku, Tokyo, 171-8588, Japan 10.3762/bjoc.16.198 Abstract The trifluoromethylation of iodoarenes was accomplished by use of a 2

• ][16][17][18][19][20][21]. For example, R3SiCF3, a fluoral derivative, and trifluoroacetates were employed as precursors of CuCF3 species for the catalytic trifluoromethylation of iodoarenes (Figure 1a) and the development of novel types of trifluoromethylating reagents is still desired. We have

• recently reported the trifluoromethylation of iodoarenes by use of 2-aryl-2-trifluoromethylbenzimidazoline as the trifluoromethylating reagent in the presence of 3 equiv of a copper salt [22]. The benzimidazoline derivatives could be readily prepared from relatively cheap materials, namely

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

• the expected PhenCuCF2CF3 reagent (Scheme 23). This constituted a complementary approach to the existing ones for its synthesis, as it avoided the use of TMSCF2CF3 or CF3CF2H. This copper-based reagent was then used for the pentafluoroethylation of iodoarenes [78]. The transformation was efficient and

• pentafluoroethylation of iodoarenes and aryldiazonium salts. Generation of a CuCF2CF3 reagent from TMSCF3 and applications. Funding This work was partially supported by Normandie Université (NU), the Région Normandie, the Centre National de la Recherche Scientifique (CNRS), Université de Rouen Normandie (URN), INSA

Practical tetrafluoroethylene fragment installation through a coupling reaction of (1,1,2,2-tetrafluorobut-3-en-1-yl)zinc bromide with various electrophiles

• Ken Tamamoto,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 2375–2383, doi:10.3762/bjoc.14.213

• synthetic tool for producing functional molecules with a CF2CF2 fragment. Keywords: acid chlorides; cross-coupling; iodoarenes; tetrafluoroethylene fragment; thermally stable zinc reagent; Introduction Recently, much attention has been paid to organic compounds containing a perfluoroalkylene unit, e.g

• result (64% NMR yield) was observed with 6.0 equiv of 3a in the presence of 30 mol % of Cu2O in DMF at 100 °C for 24 h (Table 2, entry 12) [38]. Using the optimal conditions for the reaction in entry 12, Table 2, various iodoarenes or -heteroarenes (3b–r) could be converted into the corresponding CF2CF2

• - (3d) or p-trifluoromethyl-substituted iodobenzene (3e) could also participate in the coupling reaction, leading to the corresponding products 4d and 4e in 53% and 75% NMR (49% and 13% isolated) yields, respectively. Notably, iodoarenes with an ethoxycarbonyl (3f) or a nitro group (3g) at the para

Recent advances in hypervalent iodine(III)-catalyzed functionalization of alkenes

• Xiang Li,
• Pinhong Chen and
• Guosheng Liu

Beilstein J. Org. Chem. 2018, 14, 1813–1825, doi:10.3762/bjoc.14.154

• properties of hypervalent iodine(III), a catalytic variant would be feasible (Scheme 1) [10][11][12][13][14][15][16][17]. In the catalytic cycle, hypervalent iodine(III) can be generated by oxidation of iodoarenes in the presence of a suitable external oxidant. In 1994, Fuchigami and Fujita reported the

• products. In addition, inorganic oxidants and peracetic acids can be used as oxidants as well. In 2005, the Ochiai and Kita groups demonstrated that m-chloroperbenzoic acid (mCPBA) was a better choice for the in situ generation of hypervalent iodine reagents through oxidation of iodoarenes [37][38]. Based

• was used as a stoichiometric oxidant [45]. In contrast to the intramolecular cyclization, the intermolecular reaction is much more attractive. Li and co-workers reported a syn-diacetoxylation of alkenes, using iodoarenes as catalyst which was oxidized to hypervalent iodine(III) by hydrogen peroxide in

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• stereoselective synthesis. Additionally, the applications of these reagents in natural product synthesis are also covered. Keywords: hypervalent iodine reagents; iodoarenes; natural products; oxidative cyclization; spirocyclic compounds; Review 1. Introduction The chemistry of spirocyclic compounds is a well

• iodine species or by generation of a similar active catalytic species in situ by the oxidation of iodoarene using a terminal oxidant. More commonly, m-chloroperbenzoic acid (mCPBA) and oxone are used as oxidant to generate the hypervalent iodine species in situ via oxidation of iodoarenes. In 2014, Singh

• using iodoarenes as precatalyst in the presence of terminal oxidants. In addition, this review highlights various stereoselective spirocyclizations using chiral hypervalent iodine reagents. Finally, the recent applications of hypervalent iodine reagents in natural product synthesis are also covered. The

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

• iodoarenes, which are released in stoichiometric amounts in any reaction mediated by λ3- or λ5-iodanes. In parallel to the development of solid-supported reagents or reactions catalytic in iodine, a third strategy has emerged to address this issue in terms of sustainability. The atom-economy of

• using Oxone as a terminal oxidant, thereby allowing for extending the scope of the reaction in terms of iodoarenes. Tandem oxidation–catalytic couplings A large range of oxidation reactions can be performed with [bis(acyloxy)iodo]arenes best represented by the commercially available reagents PhI(OAc)2

• ) [108]. The overall process affords complex nitrogen-containing compounds 92 with very good yields and complete stereocontrol starting from benzylic, allylic and adamantyl substrates. In addition, the preparation of substituted [bis(acyloxy)iodo]arenes following the reaction of iodoarenes with sodium

Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst

• Kimihiro Komeyama,
• Shunsuke Sakiyama,
• Kento Iwashita,
• Itaru Osaka and
• Ken Takaki

Beilstein J. Org. Chem. 2018, 14, 1413–1420, doi:10.3762/bjoc.14.118

• characters of organometallics depending on the central metals. Ni/Cr or Co/Cr-catalyzed NHK reaction. Functionalization of alkynes via carbocobaltation. Cyclization/borylation of alkynyl iodoarenes using the Co/Cr catalyst. Three-component coupling of aryl iodides, arenes, and aldehydes using Co/Cr catalyst

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

• this “green” reaction parameter. To overcome this obstacle, promising approaches are the use of iodoarenes as precatalysts in combination with external co-oxidants and the utilization of specific hypervalent iodine compounds (polymer-supported as well as non-polymeric species), whose reduced forms are

• iodoarenes 32. These species smoothly underwent subsequent Suzuki–Miyaura, Sonogashira and Mirozoki–Heck couplings. The respective arylated, alkynylated and alkenylated products 33a–d were obtained in high yields with excellent stereoselectivity. Due to the intramolecular pathway of the first step, high AE

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• bonds. The subsequent intramolecular substitution reaction of intermediate 61 having hypervalent iodine as a good leaving group yielded the required heterocycles. After Wirth’s report, Nevado et al. discovered a newly modified chiral iodine reagent 13 analogous to lactate-based chiral iodoarenes [53

One-pot synthesis of diaryliodonium salts from arenes and aryl iodides with Oxone–sulfuric acid

• Natalia Soldatova,
• Pavel Postnikov,
• Olga Kukurina,
• Viktor V. Zhdankin,
• Akira Yoshimura,
• Thomas Wirth and
• Mekhman S. Yusubov

Beilstein J. Org. Chem. 2018, 14, 849–855, doi:10.3762/bjoc.14.70

• substituted 2-iodobenzoic acids to arylbenziodoxoles [37][38], 2-iodobiphenyl to dibenziodolium compounds [39], iodoarenes to iodylbenzenes and [bis(trifluoroacetoxy)iodo]arenes [40][41], and for the preparation of diaryliodonium trifluoroacetates and triflates [42]. Yakura also used Oxone® as an oxidant for

Comparative profiling of well-defined copper reagents and precursors for the trifluoromethylation of aryl iodides

• Peter T. Kaplan,
• Jessica A. Lloyd,
• Mason T. Chin and
• David A. Vicic

Beilstein J. Org. Chem. 2017, 13, 2297–2303, doi:10.3762/bjoc.13.225

• employed directly or generated in situ from precursors by published reports. Relative reactivities were also found to highly dependent on the nature of the iodoarenes. Keywords: benchmarking; copper; fluorine; fluoroalkylation; trifluoromethylation; Introduction Selectively fluorinated molecules that

Iodoarene-catalyzed cyclizations of N-propargylamides and β-amidoketones: synthesis of 2-oxazolines

• Somaia Kamouka and
• Wesley J. Moran

Beilstein J. Org. Chem. 2017, 13, 1823–1827, doi:10.3762/bjoc.13.177

• conditions to effect catalytic processes with sub-stoichiometric quantities of iodine compound in the presence of an oxidant [6][7][8][9][10][11]. In this regard, we have reported the use of iodoarenes as precatalysts in the cyclizations of N-alkenylamides 1 [12], δ-alkynyl β-ketoesters 2 [13] and 5-oxo-5

• iodoarenes [15][16][17]. We wished to develop this cyclization methodology further and investigate the cyclization of the amide functional group on to alkynes and methylene groups adjacent to ketones in analogy to our previous work (Scheme 1d). This would provide two complementary routes to substituted 2

Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C–S cross-coupling reaction

• Debasish Sengupta,
• Koushik Bhowmik,
• Goutam De and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 1796–1806, doi:10.3762/bjoc.13.174

• iodoarenes and arylthiols bearing different groups like Me, OMe, F, COCH3, NO2 are equally efficient to undergo cross-coupling reactions producing the corresponding unsymmetrical diaryl sulfides 3a–i in 88–93% isolated yields (Table 2, entries 1–9). No significant influence of electron-donating or electron

An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

• Carolina S. García,
• Paula M. Uberman and
• Sandra E. Martín

Beilstein J. Org. Chem. 2017, 13, 1717–1727, doi:10.3762/bjoc.13.166

• is considerable room for improvements of the reported catalytic systems, which may involve high catalyst loadings (>1 mol %), toxic solvents, or limited application scope of iodoarenes and olefins [19]. Along with the increasing awareness about the development of sustainable catalysts, additional

Pd- and Cu-catalyzed approaches in the syntheses of new cholane aminoanthraquinone pincer-like ligands

• Nikolay V. Lukashev,
• Gennadii A. Grabovyi,
• Dmitry A. Erzunov,
• Alexey V. Kazantsev,
• Gennadij V. Latyshev,
• Alexei D. Averin and
• Irina P. Beletskaya.

Beilstein J. Org. Chem. 2017, 13, 564–570, doi:10.3762/bjoc.13.55

• arylation of aminocholanes has been described for the first time. While this Cu-catalyzed protocol provides high yields in reactions of aminocholanes with iodoarenes, Pd catalysis was found to be preferable for the reactions of aminocholanes with dichloroanthraquinones. UV–vis titration of bis(cholanylamino

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• that halogen bonding was the key interaction for catalyst action. In 2014, the Tan group revisited the original study by Bolm and co-workers and re-investigated halogen bond induced hydrogen transfer to C=N bonds (Scheme 20) [91]. Various charged and uncharged electron-deficient iodoarenes were tested

Scope and limitations of a DMF bio-alternative within Sonogashira cross-coupling and Cacchi-type annulation

• Kirsty L. Wilson,
• Alan R. Kennedy,
• Jane Murray,
• Ben Greatrex,
• Craig Jamieson and
• Allan J. B. Watson

Beilstein J. Org. Chem. 2016, 12, 2005–2011, doi:10.3762/bjoc.12.187

• Sonogashira cross-coupling: Substrate scope. Isolated yields. aYield using DMF as solvent. b2 equiv of Et3N used. c24 h reaction time. Cacchi-type annulation of o-amino/hydroxy iodoarenes. Isolated yields. aYield using DMF as solvent. Reaction optimisation and comparison with existing solvents.a Evaluation of

Flow carbonylation of sterically hindered ortho-substituted iodoarenes

• Carl J. Mallia,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1503–1511, doi:10.3762/bjoc.12.147

• h−1 of 20 in 85% isolated yield. Conclusion We have successfully demonstrated how flow chemistry can be used to enhance difficult transformations such as the palladium-catalysed hydroxy-carbonylation of ortho-substituted iodoarenes. The optimised conditions were also demonstrated to work on a number

Carbon–carbon bond cleavage for Cu-mediated aromatic trifluoromethylations and pentafluoroethylations

• Tsuyuka Sugiishi,
• Hideki Amii,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2015, 11, 2661–2670, doi:10.3762/bjoc.11.286

• ] (Scheme 15). Hemiaminal derivative 1 is readily prepared from commercially available CF3CH(OH)(OEt), which is a fluoral equivalent, and morpholine [52]. The substrate scope of the catalytic trifluoromethylation is shown in Scheme 16. Nitro, cyano, and ester groups in iodoarenes were tolerable under the

• reaction conditions of copper-catalyzed nucleophilic trifluoromethylation. Electron-rich iodoarenes underwent the nucleophilic trifluoromethylation to afford the corresponding trifluoromethylated benzenes. Furthermore, the trifluoromethyl group was introduced into naphthalenes and thiophene with hemiaminal

Cu(I)-catalyzed N,N’-diarylation of natural diamines and polyamines with aryl iodides

• Svetlana P. Panchenko,
• Alexei D. Averin,
• Maksim V. Anokhin,
• Olga A. Maloshitskaya and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2015, 11, 2297–2305, doi:10.3762/bjoc.11.250

• (10/20 mol %) catalytic system (Scheme 2, Table 2). The reactions with iodoarenes containing electron-withdrawing substituents ran successfully and corresponding diarylated products 13–16 were isolated in moderate to good yields (Table 2, entries 1–4). The difference in the preparative yields was due

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• iodoarenes in the presence of peroxides. Chiral iodoarenes, such as 197, served as the catalysts in the asymmetric C–O coupling of sulfonic acids with ketones. The enantiomeric excess of the product was not higher than 58% due, in particular, to instability of the configuration of the products, α-sulfonyloxy

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• readily available nucleophilic trifluoromethyl source after decarboxylation at high temperature in the presence of stoichiometric amounts of copper salts [78][79]. In 2011, Y. M. Li et al. showed that the Cu-catalyzed C–CF3 bond formation of iodoarenes could be achieved by using a sodium salt of