SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• , entry 10). The addition of DABCO [18] or TBAI [50], two additives known to activate azidobenziodoxolone (ABX), afforded complex mixtures with no trace of 4a (Table 1, entry 11). Acids or fluorinated alcohols were tested to activate the different hypervalent iodine reagents. While AcOH, TFA and TFE had

• iodine reagents [15][16]. Azidobenziodoxolone, also known as Zhdankin reagent, has often been used under thermal or photochemical conditions to generate the desired azide radical in a controlled fashion. However, recent safety issues arising from the shock and impact sensitivity of the compound led to

• , greatly increasing the molecular complexity of the starting substrate. Using radical chemistry would lead to a regioselective addition of azide radicals to the alkene, forming selectively the most stabilized C-centered radical. A prominent method for the generation of azide radicals relies on hypervalent

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

• tuning of the ligand and base combinations [18][19]. Thereafter, copper-catalyzed C–N bond-formation reactions have experienced unprecedented development due to mild reaction conditions and the low cost of copper salts [20][21][22]. On the other hand, hypervalent iodine reagents serve as versatile tools

• in oxidation, C–C, C–X bond formation, rearrangements, and halogenation reactions [23][24][25]. Due to the nontoxic nature, easier preparation, and handling of the hypervalent iodine reagents, many researchers are attracted to unravel the chemistry and reactivity of these reagents. Amongst different

• 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

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

• electrochemistry is a highly economical tool that avoids chemical oxidants for synthesizing hypervalent iodine reagents [30]. Iodoarenes are suitable and well-established mediators in either in- or ex-cell electrochemical processes [31][32][33][34][35][36]. Nonetheless, HVIs, DIS and CDIS have been generated by

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

• Girish Suresh Yedase,
• Sumit Kumar,
• Jessica Stahl,
• Burkhard König and
• Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

• Br2, MnO2, hypervalent iodine reagents, chromium-based reagents, activated dimethyl sulfoxide, KMnO4, OsO4, or metal-based catalysts and peroxide were used [7][8][9][10][11][12][13][14][15][16][17]. Most of these protocols produce harmful waste and some of the oxidizing reagents are considered toxic

The biomimetic synthesis of balsaminone A and ellagic acid via oxidative dimerization

• Sharna-kay Daley and
• Nadale Downer-Riley

Beilstein J. Org. Chem. 2020, 16, 2026–2031, doi:10.3762/bjoc.16.169

• establish high-yielding and selective oxidative coupling reactions, has afforded new and greener synthetic protocols for biaryls [5][6][7]. Several oxidants, such as the salts of Ag(I&II) [8], Ti(III&IV) [9], Mn(III) [10], Ce(IV) [11], Sn(IV) [12] and Fe(III) [13], as well as the hypervalent iodine reagents

• aqueous conditions to prevent complexation of the reagent and the starting material. Of the Lewis acids used, stannic chloride proved to be the most effective oxidant for dimerization (Table 1). However, the hypervalent iodine reagents PIFA and PIDA gave better results overall, affording dimer 18 in 63

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

• (alkenyl)iodonium salts, which are air- and moisture-stable, nontoxic and easy to prepare compounds, have become efficient reagents for mild and selective arylation and alkenylation reactions in organic synthesis [16][17][18]. In particular, the use of these hypervalent iodine reagents in copper catalysis

Construction of trisubstituted chromone skeletons carrying electron-withdrawing groups via PhIO-mediated dehydrogenation and its application to the synthesis of frutinone A

• Qiao Li,
• Chen Zhuang,
• Donghua Wang,
• Wei Zhang,
• Rongxuan Jia,
• Fengxia Sun,
• Yilin Zhang and
• Yunfei Du

Beilstein J. Org. Chem. 2019, 15, 2958–2965, doi:10.3762/bjoc.15.291

• high reaction temperature, extended reaction time, involvement of transition metal catalysts, and low yield. In these regards, the development of alternative approaches that can realize an efficient synthesis of chromones under mild conditions is desirable. In recent decades, hypervalent iodine

• reagents have emerged as a class of efficient and environmentally benign nonmetal “green” oxidants [66][67][68][69][70][71][72][73]. For instance, iodosobenzene (PhIO) [74] has been widely used in many synthetic transformations. It was found that PhIO is efficient in realizing epoxidation of olefins [75

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

• )cyclic iodanes. Albeit aryl-λ3-iodanes are viewed as safe and stable under ambient temperatures, systematic thermal degradation studies of hypervalent iodine reagents are still rare. In 1992 Varvoglis and co-workers investigated the thermal degradation of a variety of aryl iodine(III) dicarboxylates into

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• , hypervalent iodine reagents, etc. The synthetic methods towards diverse [1,2,4]triazolo[3,4-a]pyridines have been reviewed in detail [12][13]. It should be noted that the use of acetylene species to create this heterocycle (including triazole ring) is presented only by few examples. There has been reported

The mechanochemical synthesis of quinazolin-4(3H)-ones by controlling the reactivity of IBX

• Md Toufique Alam,
• Saikat Maiti and
• Prasenjit Mal

Beilstein J. Org. Chem. 2018, 14, 2396–2403, doi:10.3762/bjoc.14.216

• may take place between hypervalent iodine reagents and electron-rich amines. For this reason, synthetic methods based on hypervalent iodine reagents and primary amines under solvent-free conditions or constrained media are limited [8]. Recently, we have described a method for the successful reaction

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

• 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

• rationalized by Woodward dioxolane intermediates (Scheme 3). Stereoselective dioxygenation using catalytic amounts of chiral hypervalent iodine reagents is a comparatively new area in hypervalent iodine chemistry. Fujita and co-workers described a stereoselective oxylactonization reaction in the presence of a

• first a nucleophilic attack from the vinylogous ester, then by the aromatic group, providing the final outcomes. Wirth and co-workers developed an oxidative rearrangement of alkenes to chiral α-aryl ketones, in which electron-deficient chiral lactic acid-based hypervalent iodine reagents were

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

• Fateh V. Singh Priyanka B. Kole Saeesh R. Mangaonkar Samata E. Shetgaonkar Chemistry Division, School of Advanced Sciences (SAS), VIT University, Chennai Campus, Chennai-600 127, Tamil Nadu, India 10.3762/bjoc.14.152 Abstract Hypervalent iodine reagents have been developed as highly valuable

• reagents in synthetic organic chemistry during the past few decades. These reagents have been identified as key replacements of various toxic heavy metals in organic synthesis. Various synthetically and biologically important scaffolds have been developed using hypervalent iodine reagents either in

• stoichiometric or catalytic amounts. In addition, hypervalent iodine reagents have been employed for the synthesis of spirocyclic scaffolds via dearomatization processes. In this review, various approaches for the synthesis of spirocyclic scaffolds using hypervalent iodine reagents are covered including their

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• glycosylation of the sulfoxide 32 could be performed in the same flask, the reaction could bypass two of the reaction steps and would directly produce 4’-thionucleoside 35 from 31. Indeed, the utilization of hypervalent iodine would have enabled this short-cut reaction (Figure 2). Hypervalent iodine reagents

• reported by Kita and co-workers [44]. Their paper prompted Nishizono et al. to study the glycosylation reaction for 4’-thionucleosides using hypervalent iodine reagents. As a 4-thiosugar donor, 2-p-methoxybenzoate derivative 36 was prepared following Matsuda’s method as shown in Scheme 2, and then was

• reaction of 36 with iodosylbenzene (PhI=O) proceeded stereoselectively and gave only the β-anomer of 37 in 53% yield [45] (Scheme 4). The mechanism of hypervalent iodine-mediated glycosylation can be expressed as shown in Figure 3. The activated hypervalent iodine reagents in the presence of TMSOTf reacted

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

• application of modern transition-metal-catalyzed methods. Simple hypervalent iodine reagents can now be considered as valuable building blocks in the synthesis of both polyfunctionalized compounds and complex polycyclic skeletons. We believe that the application of this strategy could be a source of

Synthesis of trifluoromethylated 2H-azirines through Togni reagent-mediated trifluoromethylation followed by PhIO-mediated azirination

• Jiyun Sun,
• Xiaohua Zhen,
• Huaibin Ge,
• Guangtao Zhang,
• Xuechan An and
• Yunfei Du

Beilstein J. Org. Chem. 2018, 14, 1452–1458, doi:10.3762/bjoc.14.123

• -dimethyl-1,2-benziodoxole (1’, Figure 2), are effective and efficient hypervalent iodine reagents for trifluoromethylation reactions of a variety of substrates [22][23]. These reagents have found wide applications in the area of organofluorine chemistry, synthetic method development as well as medicinal

• [52][53][54][55] have been developed for accessing this exclusive class of heterocycles. In our previous works, we have realized the application of hypervalent iodine reagents for the construction of the 2H-azirine skeleton starting from enamines 2 via intramolecular oxidative cyclization (Scheme 1

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

• -economical transformations using hypervalent iodine reagents (iodanes) as electrophilic group-transfer reagents. Iodanes, in particular iodonium salts, are well-balanced reagents in terms of stability, reactivity and synthetic and/or commercial availability and therefore it is not surprising to see these

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

• last 25 years. This review highlights the contribution of different chiral hypervalent iodine reagents in diverse asymmetric conversions. Keywords: alkene functionalization; asymmetric synthesis; hypervalent iodine; organocatalysis; oxidation; Introduction It is more than one century ago since the

• reagents [2][3][4][5][6][7][8][9][10][11][12][13][14]. These compounds feature a unique three-centered four-electron bond [15][16][17][18][19][20] that renders them valuable and important alternatives to transition-metal chemistry. Over the last 25 years hypervalent iodine reagents have gained growing

• turned the attention of the scientific community towards the evolution of new chiral hypervalent iodine reagents. In recent years, many complex synthetic challenges have been successfully addressed by applying these reagents [21][22]. The superior advantage of these reagents lies in their strong

Rhodium-catalyzed C–H functionalization of heteroarenes using indoleBX hypervalent iodine reagents

• Erwann Grenet,
• Ashis Das,
• Paola Caramenti and
• Jérôme Waser

Beilstein J. Org. Chem. 2018, 14, 1208–1214, doi:10.3762/bjoc.14.102

• heteroarenes was realized using the benziodoxolone hypervalent iodine reagents indoleBXs. Functionalization of the C–H bond in bipyridinones and quinoline N-oxides catalyzed by a rhodium complex allowed to incorporate indole rings into aza-heteroaromatic compounds. These new transformations displayed complete

• nitrogen and a transition metal catalyst (reaction 1, Scheme 1A) [11][12][13][14][15][16][17][18][19]. In particular, Li and co-workers have used ethynylbenziodoxolone (EBX) hypervalent iodine reagents to achieve a regiodivergent alkynylation of the pyridinone core employing either a gold(I) or a rhodium

• (III) catalyst for C-5 and C-6 functionalization, respectively [13]. Hypervalent iodine reagents in general [20], and benziodoxole derivatives in particular [21], have found broad application in synthetic chemistry. Aryl iodonium salts have been used successfully in transition-metal-catalyzed

Rapid transformation of sulfinate salts into sulfonates promoted by a hypervalent iodine(III) reagent

• Elsa Deruer,
• Vincent Hamel,
• Samuel Blais and
• Sylvain Canesi

Beilstein J. Org. Chem. 2018, 14, 1203–1207, doi:10.3762/bjoc.14.101

• aromatic systems or cyclic ethers through a ring opening pathway. Keywords: hypervalent iodine; oxidation; sulfinates; sulfonation; sulfonium; Introduction Over the past few decades, hypervalent iodine reagents [1][2][3][4] have emerged as versatile and environmentally benign substitutes for heavy metal

• diol derivative containing a linear chain in only one step. One alcohol is available as a leaving group and the second is protected by conversion into a trichloroacetate moiety (Scheme 4). Conclusion A novel oxidative method for producing sulfonates from sulfinates using hypervalent iodine reagents has

Recyclable hypervalent-iodine-mediated solid-phase peptide synthesis and cyclic peptide synthesis

• Dan Liu,
• Ya-Li Guo,
• Jin Qu and
• Chi Zhang

Beilstein J. Org. Chem. 2018, 14, 1112–1119, doi:10.3762/bjoc.14.97

• . Hypervalent iodine reagents have drawn researchers’ considerable attentions due to their versatile reactivity, low toxicity, ready availability, environmental friendliness, and regenerability [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Our group has dedicated to the peptide synthesis

Iodine(III)-mediated halogenations of acyclic monoterpenoids

• Laure Peilleron,
• Tatyana D. Grayfer,
• Joëlle Dubois,
• Robert H. Dodd and
• Kevin Cariou

Beilstein J. Org. Chem. 2018, 14, 1103–1111, doi:10.3762/bjoc.14.96

• halogenations with increased selectivity. In this regard, hypervalent iodine reagents [6] have emerged as particularly versatile mediators [7][8][9][10]. We have shown that electrophilic halogenations [11][12][13], or pseudohalogenations [14] can be triggered by combining an iodine(III) derivative with a

Selective carboxylation of reactive benzylic C–H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system

• Toshifumi Dohi,
• Shohei Ueda,
• Kosuke Iwasaki,
• Yusuke Tsunoda,
• Koji Morimoto and
• Yasuyuki Kita

Beilstein J. Org. Chem. 2018, 14, 1087–1094, doi:10.3762/bjoc.14.94

• , reports aimed at realizing efficient and selective metal-free C(sp3)–H transformations are rather limited; however, investigations by several research groups are still ongoing [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Hypervalent iodine reagents are now widely accepted as a safe

• oxidations was recognized for displaying the new reactivities of hypervalent iodine reagents toward C(sp3)–H bonds [38][39]. By exploiting the radical behavior of trivalent iodine reagents discovered previously [40][41], the activation of trivalent iodine reagents, e.g., phenyliodine(III) diacetate (PIDA

Hypervalent iodine-guided electrophilic substitution: para-selective substitution across aryl iodonium compounds with benzyl groups

• Cyrus Mowdawalla,
• Faiz Ahmed,
• Tian Li,
• Kiet Pham,
• Loma Dave,
• Grace Kim and
• I. F. Dempsey Hyatt

Beilstein J. Org. Chem. 2018, 14, 1039–1045, doi:10.3762/bjoc.14.91

• mechanism could be occurring with metalloid groups such as silicon and boron. Hypervalent iodine reagents such as Zefirov’s reagent, cyclic iodonium reagents, iodosobenzene/BF3, and PhI(OAc)2/BF3 or triflate-based activators were tested. A desirable facet of the reported reaction is that iodine(I) is

• that many of these useful reagents became a staple in synthetic chemistry laboratories [1][2]. Although hypervalent iodine reagents are commonly used in oxidation reactions, they have also found their own niche in useful C–C bond-formation and C–H activation reactions [3][4][5]. One such C–C bond

Hypervalent iodine-mediated Ritter-type amidation of terminal alkenes: The synthesis of isoxazoline and pyrazoline cores

• Sang Won Park,
• Soong-Hyun Kim,
• Jaeyoung Song,
• Ga Young Park,
• Darong Kim,
• Tae-Gyu Nam and
• Ki Bum Hong

Beilstein J. Org. Chem. 2018, 14, 1028–1033, doi:10.3762/bjoc.14.89

• 3a albeit in low yield (Table 1, entry 1). The background reaction mediated by a Lewis acid seemed plausible via an electrophilic activation of the double bond. When the reaction is performed in the presence of hypervalent iodine reagents such as PIFA ([bis(trifluoroacetoxy)iodo]benzene), PhI(NPhth)2