Direct electrochemical generation of organic carbonates by dehydrogenative coupling

• Tile Gieshoff,
• Vinh Trieu,
• Jan Heijl and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2018, 14, 1578–1582, doi:10.3762/bjoc.14.135

• organic acetonitrile-based electrolyte system. Acetonitrile tolerates highly positive potential regimes, which are necessary for C–H activation of non-functionalized arenes. Since simple metal-based carbonate salts are not sufficiently soluble in organic media, the choice of carbonate source is crucial

• nucleophilicity of carbonates is limited and therefore, the choice of suitable arenes is crucial. Heterofunctionalizations like fluoro, chloro, and methoxy groups are generally accepted, but it depends on the substitution pattern. The sensitive interplay of inefficient oxidation at highly positive oxidation

• potentials and the oligomerization tendency of electron-rich arenes limit the scope (see Supporting Information File 1). Conclusion The first direct electrochemical generation of organic carbonates by dehydrogenative coupling at arenes was established. Even though this ambitious method is currently

A conformationally adaptive macrocycle: conformational complexity and host–guest chemistry of zorb[4]arene

• Liu-Pan Yang,
• Song-Bo Lu,
• Arto Valkonen,
• Fangfang Pan,
• Kari Rissanen and
• Wei Jiang

Beilstein J. Org. Chem. 2018, 14, 1570–1577, doi:10.3762/bjoc.14.134

• biomimetic structures [24]: endo-functionalized molecular tubes [25][26][27][28][29][30] and conformationally adaptive macrocycles [31][32][33][34][35][36][37]. Among the conformationally adaptive macrocycles two types were reported: oxatub[n]arenes [31][32][33][34][35][36] and zorb[n]arenes [37]. These

• network. We have carefully looked into the properties of oxatub[n]arenes and found that the macrocycles have many unique properties. For example, oxatub[4]arene has a wide guest scope and can bind almost all of the common organic cations [32]. It also shows conformational responses to solvent change [33

• ] and remote electronic substituents on the guests [34]. In addition, different alkyl side chains on oxatub[4]arenes lead to different macroscopic self-assembly behaviors [36]. Zorb[4]arene was first synthesized, reported and so named by the Georghiou group in 2005. The derivatives per-O-methoxy- and

Cobalt-catalyzed C–H cyanations: Insights into the reaction mechanism and the role of London dispersion

• Eric Detmar,
• Valentin Müller,
• Daniel Zell,
• Lutz Ackermann and
• Martin Breugst

Beilstein J. Org. Chem. 2018, 14, 1537–1545, doi:10.3762/bjoc.14.130

• cyanation of arenes (Scheme 2) [30][31][32][33][34]. Dispersion effects can be envisioned to be highly important in this system, as the relatively C–H-rich ligand Cp* can interact with both substrates within the cobalt complexes. In 2015, Li and Ackermann have proposed the catalytic cycle (C–H cobaltation

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

• , arenes and heteroarenes [43][44]. A first solution to value the 2-iodobenzoic moiety released from EBX has arisen from the reaction of derivatives 22 with N-(aryl)imines 23 in the presence of 10 mol % of Pd(OAc)2, which gives access to tri- or tetrasubstituted furans 24 and N-(aryl)formamides 25 (Scheme

• this issue of atom-economy, the group of Shafir has reported the metal- and base-free arylation of keto-esters and cyanoketones using [bis(trifluoroacetoxy)iodo]arenes ArI(OCOCF3)2 (Scheme 40) [78]. The reaction can also be applied to cyclic 1,3-diones with equal efficiency [79]. Mechanistic studies

• 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

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

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• chiral calix[4]arenes (±)-1 and (±)-2 containing a quaternary ammonium moiety together with a hydroxymethyl and diarylmethanol moiety in an optically pure form, respectively (Figure 1) [37]. In order to see the beneficial effect of the diarylmethanol structure in this catalysts, they were applied to the

• asymmetric phase-transfer catalysis based on inherently chiral calix[4]arenes, although the asymmetric induction observed remained moderate. Su et al. demonstrated a new approach for the design of a chiral binary integrative phase-transfer catalyst consisting of p-tert-butylcalix[4]arene and a cinchonine

• investigated. Under optimized conditions, up to 47% ee was obtained by alkylation of 3 with 4-methylbenzyl bromide in the presence of 5 mol % catalyst 12. Henry reaction Since lower-rim functionalization of calix[4]arene is relatively easy, a variety of inherently chiral calix[4]arenes substituted at the lower

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

• only one equivalent of the iodane 1a would have been sufficient. In recent years a variety of domino C–H and/or N–H arylations as powerful tools towards selective diarylations of (hetero)arenes was employed by Greaney and co-workers, who were among the first to establish more atom-economical procedures

A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

• Anna Czarnecka,
• Emilia Kowalska,
• Agnieszka Bodzioch,
• Joanna Skalik,
• Marek Koprowski,
• Krzysztof Owsianik and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105

• was observed instead [23]. Diarylmethanes were also obtained in the Friedel–Crafts reactions of arenes with primary benzyl alcohols, aryl acetals, and benzyl esters [1]. Benzyl fluorides (in 1,1,1,3,3,3-hexafluoroisopropanol in the presence of a catalytic amount of trifluoroacetic acid [24]) as well

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

• peptidocalix[4]arenes with arginine-rich short narrow groove binding residues on the lower rim of the calix[4]arene scaffold were reported by Soltani et al. in order to study the binding between well-matched and mismatched DNA duplexes [107]. Fluorescent titrations, ethidium bromide (EB) displacement assays

Polysubstituted ferrocenes as tunable redox mediators

• Sven D. Waniek,
• Jan Klett,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2018, 14, 1004–1015, doi:10.3762/bjoc.14.86

• reactions [29], borylations of arenediazonium salts [30] and in C–H imidation reactions of (hetero)arenes [31] (Scheme 1b,c). Ferrocene has been used as redox mediator for the electrochemical modification of carbon surfaces via electrochemical oxidation of carboxylates [32][33], as mediator for

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

• -donating or electron-withdrawing groups in good yields. In addition, this procedure can be applied to the preparation of symmetric iodonium salts directly from arenes via a one-pot iodination–oxidation sequence. Keywords: diaryliodonium salts; iodine; iodonium; oxidation; Oxone; Introduction

• based on the use of inexpensive, commercially available oxidants is an important and challenging goal. A vast majority of existing procedures involve the interaction of electrophilic hypervalent iodine(III) species with suitable arenes through ligand exchange processes [16][17][18][19][20]. The reactive

• hypervalent iodine(III) species can be used as stable reagents or can be generated in situ [21][22][23][24][25]. In particular, Olofsson and co-workers reported procedures based on the in situ generation of reactive λ3-iodane species directly from arenes, which was a significant achievement in this field [26

Cobalt-catalyzed directed C–H alkenylation of pivalophenone N–H imine with alkenyl phosphates

• Wengang Xu and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2018, 14, 709–715, doi:10.3762/bjoc.14.60

• groups into the ortho position of functionalized arenes has attracted significant attention because of the synthetic versatility of alkenyl groups. The C–H alkenylation has been achieved most extensively by way of the dehydrogenative Heck-type reaction of olefins [7][8][9]. Meanwhile, the hydroarylation

Synthesis of fluoro-functionalized diaryl-λ³-iodonium salts and their cytotoxicity against human lymphoma U937 cells

• Prajwalita Das,
• Etsuko Tokunaga,
• Hidehiko Akiyama,
• Hiroki Doi,
• Norimichi Saito and
• Norio Shibata

Beilstein J. Org. Chem. 2018, 14, 364–372, doi:10.3762/bjoc.14.24

• ylides, and (diacyloxyiodo)arenes were also examined for their antibacterial activities against ice nucleation active Pseudomonas syringae, and aryliodonium salts, especially those with electron-withdrawing groups, exhibit higher antibacterial activities [49]. Despite the long history of diaryliodonium

• proceed with a further investigation of the synthesis of ortho-SF5 phenyl aryliodonium salts. Four ortho-SF5-substituted diaryliodonium salts were designed with different arenes as auxiliary groups, namely, electron-rich with sterically demanding mesitylene type 3p and triisopropylphenyl type 4b, electron

Diels–Alder cycloadditions of N-arylpyrroles via aryne intermediates using diaryliodonium salts

• Huangguan Chen,
• Jianwei Han and
• Limin Wang

Beilstein J. Org. Chem. 2018, 14, 354–363, doi:10.3762/bjoc.14.23

• coupling products were obtained in moderate to good yields (Scheme 1a) [6]. Later in 2013, Xue and Xiao et al. developed a method of photoredox catalysis in the presence of [Ru(bpy)3]2+ with visible light for the coupling reaction of arenes with unprotected or N-substituted pyrroles, pyrrole substrates

One-pot sequential synthesis of tetrasubstituted thiophenes via sulfur ylide-like intermediates

• Jun Ki Kim,
• Hwan Jung Lim,
• Kyung Chae Jeong and
• Seong Jun Park

Beilstein J. Org. Chem. 2018, 14, 243–252, doi:10.3762/bjoc.14.16

• compounds 7f and 7g, the low reactivity resulted from the decreased mesomeric effect of the furan structure: the higher electronegativity of oxygen facilitated the polarized form [71]. Among various arenes, the 4-nitrophenyl substituent 7p only afforded the desired thiophene 8p in a moderated yield (42

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• target functional groups. Recently, several examples of conversion of anilines into trifluoromethylated arenes, named Sandmeyer type trifluoromethylation, were disclosed. This protocol offered a complementary method for the synthesis of trifluoromethylated arenes from the corresponding aromatic amines

• . In 2013, Fu [43], Gooßen [44] and Wang [45] almost simultaneously reported Sandmeyer type trifluoromethylations. The group of Fu [43] accomplished a copper-mediated Sandmeyer trifluoromethylation reaction for the conversion of aromatic amines into trifluoromethylated arenes (Scheme 24). This reaction

• compound were based on the use of prefunctionalized substrates. Instead, the direct trifluoromethylation of C–H bonds of arenes and heteroarenes was a more efficient and ideal protocol due to its atom and step economy. However, the direct trifluoromethylation of C–H bonds was not simple. And only in recent

Aminomethylation/hydrogenolysis as an alternative to direct methylation of metalated isoquinolines – a novel total synthesis of the alkaloid 7-hydroxy-6-methoxy-1-methylisoquinoline

• Benedikt C. Melzer,
• Jan G. Felber and
• Franz Bracher

Beilstein J. Org. Chem. 2018, 14, 130–134, doi:10.3762/bjoc.14.8

• , the unsatisfactory separation of 1-methylisoquinoline intermediate 4 from its unmethylated precursor 3 rendered this protocol unattractive. This is a problem that is common to numerous methylation protocols, including methylation of metalated arenes [16], methylation of arenes bearing directing groups

• alkaloid 7-hydroxy-6-methoxy-1-methylisoquinoline (1), but should also be of value for the synthesis of other 1-methylisoquinolines. We could demonstrate that the aminomethylation of metalated arenes with Eschenmoser’s salt followed by hydrogenolytic cleavage is a highly attractive alternative to direct

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• the preparation of sulfoxides was recently reported by our laboratory (Scheme 49) [86]. Sulfinamides were applied as sulfinylation reagents for a diversified scope of arenes and heteroarenes with ammonium persulfate ((NH4)2S2O8) as oxidant under irradiation with visible light. Although none of the

• arenes react well and substituted pyrroles and indoles give the corresponding sulfoxides in high yields. Less electron-rich thiophene or benzene derivatives gave low yields. Nevertheless, carbocyclic azulene afforded the respective sulfoxide in 88% yield. We propose an electrophilic aromatic substitution

• two arenes with different nucleophilicity, which were reacted with one sulfinamide. The respective product with the stronger nucleophile is formed exclusively. In reactions with two arenes having similar nucleophilicity a mixture of the respective products was obtained. Sulfonyl halides and

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• additional step of intramolecular cyclisation. An alternative radical chain process was also considered this time, involving notably the reaction of radical 28 with CF3SO2Cl to produce CF3• and intermediate 29. Csp2–CF3 bond-forming reactions Trifluoromethylation of arenes and heteroarenes: The pioneering

• example of such transformation was reported in 1990 by Kamigata and co-workers, and described the introduction of the CF3 moiety onto arenes in the presence of a catalytic amount of RuCl2(PPh3)3 (Scheme 24) [6][7]. This reaction, however, suffered from limitations, such as its poor regioselectivity in the

• case of monosubstituted arenes, and its incompatibility with aromatics bearing strong electron-withdrawing groups. The authors proposed the mechanism represented in Scheme 24. A redox-transfer reaction occurred between CF3SO2Cl and the Ru(II) catalyst producing radical anion 30, which then furnished

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• arenes and heteroarenes: In 1991, Langlois and co-workers reported the first trifluoromethylation of aromatic compounds with sodium trifluoromethanesulfinate under oxidative conditions (Scheme 34) [16]. The scope was quite narrow with electron-rich aromatics and mixtures of regioisomers were often

• -position of pyridinones facilitated the trifluoromethyl radical attack [63]. Catalytic amounts of phosphovanadomolybdic acid, a heteropolyacid catalyst (HPA), was used by Mizuno, Yamaguchi and co-workers for the oxidative C−H trifluoromethylation of arenes and heteroarenes in the presence of CF3SO2Na and

• O2 as the terminal oxidant. This method allowed the trifluoromethylation of arenes bearing electron-donating as well as electron-withdrawing groups in moderate to good yields (Scheme 41) [64]. It has to be noted that bis-CF3 products as well as regioisomers were also characterised or detected in

Binding abilities of a chiral calix[4]resorcinarene: a polarimetric investigation on a complex case of study

• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2698–2709, doi:10.3762/bjoc.13.268

• : calix[4]resorcinarene; host–guest complexes; p-nitroanilines; polarimetry; supramolecular chemistry; Introduction During the last decades calix[n]arenes and calix[n]resorcinarenes (CAs) have emerged as versatile supramolecular host systems for various applications [1][2][3][4][5], spanning from sensors

Syntheses, structures, and stabilities of aliphatic and aromatic fluorous iodine(I) and iodine(III) compounds: the role of iodine Lewis basicity

• Tathagata Mukherjee,
• Soumik Biswas,
• Andreas Ehnbom,
• Subrata K. Ghosh,
• Ibrahim El-Zoghbi,
• Nattamai Bhuvanesh,
• Hassan S. Bazzi and
• John A. Gladysz

Beilstein J. Org. Chem. 2017, 13, 2486–2501, doi:10.3762/bjoc.13.246

• chronological order, focusing first on arenes with one Rfn substituent. As shown in Scheme 5 (top), the commercially available meta diiodide 1,3-C6H4I2 was treated with copper (1.0 equiv) and Rf6I (0.5 equiv; a deficiency to help suppress dialkylation) in DMSO at 110 °C. Similar recipes have previously been

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• ethers of α-halooximes 2) in the reaction with organometallic compounds may lead to further developments in this promising methodology. Addition of arenes to conjugated nitrosoalkenes Besides common C-nucleophiles, nitrosoalkenes can react with nucleophilic arenes and heteroarenes. Gilchrist and Roberts

• NSA14 to electron-rich arenes. Addition of nitrosoalkenes NSA14 to pyrroles and indoles. Reaction of phosphinyl nitrosoalkenes NSA15 with indole. Reaction of pyrrole with α,α’-dihalooximes 70. Synthesis of indole-derived psammaplin A analogue 72. Synthesis of tryptophanes by reduction of

p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests

• Alena A. Vavilova and
• Ivan I. Stoikov

Beilstein J. Org. Chem. 2017, 13, 1940–1949, doi:10.3762/bjoc.13.188

• Alena A. Vavilova Ivan I. Stoikov Kazan Federal University, Kremlevskaya, 18, Kazan 420008, Russian Federation 10.3762/bjoc.13.188 Abstract New p-tert-butylthiacalix[4]arenes, which are mono-, 1,2-di- and tetrasubstituted at the lower rim containing N-(4’-nitrophenyl)acetamide and N,N

• receptors for F−, CH3CO2− and H2PO4− ions, which based on the synthesized thiacalix[4]arenes, have been obtained. It was shown that p-tert-butylthiacalix[4]arene tetrasubstituted at the lower rim by N-(4’-nitrophenyl)acetamide moieties bonded to the anions studied with association constants within the range

• ,N-diethylacetamide fragment and its further functionalization with the N-(4’-nitrophenyl)acetamide moiety. We also calculated the proposed model of anion binding for the new and previously synthesized thiacalix[4]arenes and compared their complexation properties toward number of singly charged