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

• (trifluoroacetoxy)iodo]arene. Catalytic nitrene additions mediated by [bis(acyloxy)iodo]arenes. Tandem of C(sp3)–H amination/sila-Sonogashira–Hagihara coupling. Tandem reaction using a λ3-iodane as an oxidant, a substrate and a coupling partner. Synthesis of 1,2-diarylated acrylamidines with ArI(OAc)2

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

• Alberto Spinella,
• Marco Russo,
• Antonella Di Vincenzo,
• Delia Chillura Martino and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127

• preliminary tests to assess their supramolecular absorption abilities towards a set of suitable organic guests, selected as pollutant models. The synthesis was accomplished by means of a CuAAC reaction between a tetrakis(propargyloxy)calix[4]arene and an alkyl diazide. The formation of the polymeric network

• ]) between a heptakis(6-azido-6-deoxy)-β-cyclodextrin and a tetrakis(propargyloxy)calix[4]arene [11][31][32]. In this way, a random disposition of the co-monomer units linked by 1,2,3-triazole units is achieved. The obtained CyCaNSs benefit from several advantages. First, the properties of the material can

• ), in which the host monomers are joined by means of bis(1,2,3-triazole) subunits having different features. More in detail, four different nanosponges CaNS1-CaNS4 were obtained by reacting the 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(propargyloxy)calix[4]arene (Ca-OP, Scheme 1a) with four

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

• 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

• ammonium salt [38] (Scheme 2). Due to the failure of obtaining monobromo p-tert-butylcalix[4]arene derivative 6 directly from p-tert-butylcalix[4]arene using 1,2-dibromoethane in the presence of several bases, the synthetic route to calixarene-based chiral phase-transfer catalyst 7 comprises a four-step

• sequence including protection/deprotection steps for the benzyl groups. The catalytic efficiency of calix[4]arene-based phase-transfer catalyst 7 was evaluated in the benchmark reaction (Scheme 3) and compared with that of the chiral quaternary ammonium salt 8. The results obtained when 7 used as

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

• monoarylations, produces not only the aryl iodide, but also stoichiometric amounts of salt side-products, limiting the AE of these transformations to roughly 10–20% (Scheme 1, reaction (a)). In the second case, both organic residues (one carbon or heteroatom ligand plus the arene of the former aryl-λ3-iodane or

• describe an efficient α-arylation of a variety of 1,3-dicarbonyl derivatives 21 using [bis(trifluoroacetoxy)iodo]benzene (20a, PIFA). In this metal-free approach the target structures 22 are efficiently synthesised even without any initial prefunctionalisation of the arene moiety (Scheme 13). Remarkably

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

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

• , reaction 1). Yet in the course of our study we also showed that the reactivity of the key bridged bromonium intermediate could also be steered towards non-cyclizing vicinal difunctionalizations using slightly different combinations of a (diacyloxyiodo)arene and a bromide salt. Indeed, (diacetoxy

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

Imide arylation with aryl(TMP)iodonium tosylates

• Souradeep Basu,
• Alexander H. Sandtorv and
• David R. Stuart

Beilstein J. Org. Chem. 2018, 14, 1034–1038, doi:10.3762/bjoc.14.90

• , transition metals feature prominently in such methods, but even recent examples employ stoichiometric metal mediators [4]. Metal-free methods by classic SNAr are also attractive, but only possible on very electron-deficient arene substrates [5]. Diaryliodonium salts are useful reagents for metal-free aryl

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

• –m in lower yields. Similar reactions of 3,5-bis(trifluoromethyl)iodobenzene (1d) with benzene and mesitylene formed the corresponding iodonium salts 3n and 3o in moderate yields. With electron-deficient arenes 2 such as chlorobenzene (2e) and benzene, an excess of sulfuric acid and arene was used to

Phosphodiester models for cleavage of nucleic acids

• Satu Mikkola,
• Tuomas Lönnberg and
• Harri Lönnberg

Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68

• by calix[4]arene derivatives 7 bearing the guanidine groups at the upper rim and O-(2-ethoxyethyl) groups at the lower rim [80]. The role of the latter groups was to improve solubility to hydroxylic solvents and to rigidify the calixarene system into the so-called cone conformation. HPNP (1) was used

• hydroxy function on phosphorus (Scheme 8). Similar results were obtained on using diphenylmethane as a scaffold 8 (Figure 8) [81]. A cyclohexylidene or adamantylidene substituent on the methylene carbon moderately enhanced the catalytic activity. Interestingly, the calix[4]arene-based agent 7 catalyzed

Chlorination of phenylallene derivatives with 1-chloro-1,2-benziodoxol-3-one: synthesis of vicinal-dichlorides and chlorodienes

• Zhensheng Zhao and
• Graham K. Murphy

Beilstein J. Org. Chem. 2018, 14, 796–802, doi:10.3762/bjoc.14.67

• ) on the arene also deviated from the expected reaction course. These reactions failed to fully consume the starting materials 2u and 2v, even upon prolonged heating, which we discovered to be the result of 1b being also consumed through over-chlorination. 4-Methoxy derivative 2u gave trichloride 5u in

• as resulting from the stabilization of radical intermediates gained upon methoxy substitution [51], which permitted further chlorination of either the methyl or arene groups. To gain insight into the reaction mechanism we carried out two key control experiments. First, to test for rearrangement

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

• , directing group-assisted arene C–H activation reactions have been extensively studied over the last few decades to offer a broad array of atom and step-economical methods for the synthesis of functionalized aromatic compounds [1][2][3][4][5][6]. Among various C–H transformations, the introduction of alkenyl

• (e.g., acrylates), and is challenging with unactivated and multisubstituted alkenes [11]. The hydroarylation of alkynes does not allow for the introduction of cycloalkenyl groups because of the unavailability of the corresponding alkynes. In light of such limitations, a coupling between arene

• ) from ketones [13][14][15][16][17]. Over the last several years, we and others have developed a series of directed arene C–H functionalization reactions with organic electrophiles under low-valent cobalt catalysis [18][19][20][21]. In particular, our group and the Ackermann group have independently

Carbohydrate inhibitors of cholera toxin

• Vajinder Kumar and
• W. Bruce Turnbull

Beilstein J. Org. Chem. 2018, 14, 484–498, doi:10.3762/bjoc.14.34

• , indicating that the central cyclic peptide core probably has an expanded ring conformation. Garcia-Hartjes et al. synthesised and evaluated the GM1os linked calix[5]arene molecule 31 as shown in Figure 12, and found that compound 31 displayed 100,000 times more potency as compared to GM1os derivatives having

• inhibitor designed and synthesised by Pieters, and Bernardi et al. Cyclic inhibitors synthesised by Kumar et al. for CT. The star-shaped inhibitors reported by Fan, Hol and co-workers. Differently sized cyclic decavalent peptide core designed by Zhang et al. Calix[5]arene core-based pentavalent inhibitor

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

• [65][66]. This synthesis was achieved by treating iodide 7 with the respective arene, m-CPBA, and trifluoromethanesulfonic acid at room temperature. The desired diaryliodonium salts 3p, 4b, 5a and 6a were obtained in good yields (72%, 86%, 81% and 92%, respectively) (Scheme 2). The newly synthesized

• for 1 h before the addition of 7 (1.0 equiv) and CH2Cl2 (6.0 mL/mmol ArI) in a round-bottomed flask. The solution was cooled to 0 °C followed by the dropwise addition of TfOH (1.7 equiv). The resulting mixture was stirred at room temperature for 2 h. It was then cooled to 0 °C and the arene (1.1 equiv

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

• effect of the amine might be attributed to the resonance structures of imidazole (Table 1, entry 11) [72]. To determine the influence of substituents on the phenyl group, various arene(methyl)sulfanes 7l–p were tested (Table 1, entries 12–16,). Simple phenyl and electron-donating compounds 7l and 7m did

• -pot sequential synthesis of the trisubstituted 5-(pyridine-2-yl)thiophenes 8a. Substrate: amalonitrile; b5,5-dimethylcyclohexane-1,3-dione. The substitution reaction with MeOH. Examination of N,S-acetals substituted with a heterocycle (7aa–k) or an arene (7l–p). 1H NMR studies of Meldrum’s acid-based

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

• corresponding hydroxylated arene) was readily removable by extraction or column chromatography. Later, the group of Beller [42] described another example of copper-catalyzed trifluoromethylation reactions of aryl- and vinylboronic acids with CF3SO2Na as the trifluoromethyl source (Scheme 23). The

• groups were tolerated in these conditions, such as sulfonate, nitro, ester, amide, ether, and even unprotected hydroxy groups. In addition, arene rings bearing chloro and iodo groups did not interfere with the transformation, which promised further conversion at the halogenated positions. It was notable

From dipivaloylketene to tetraoxaadamantanes

• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1

• of the bisdioxines becomes severely hindered in cyclic derivatives, so that the 38-membered ring compound 32 requires microwave heating at 170 °C to form tetraoxaadamantane 33, and the catenated compound 36 and calix[6]arene derivative 37 did not form tetraoxaadamantanes. The reaction mechanisms of

• -butylcalix[6]arene moiety in 37 (Figure 3), which is obtained from the bisdioxine diacid dichloride 12 and calixarene [42]. The wider upper rim is clearly seen in the X-ray structure and the compound demonstrates a pronounced ability to extract Cs+ ions from water into chloroform by forming endohedral

• 38-membered ring 32 requires forcing conditions to form a tetraoxaadamantane, and compounds 36 and 37 did not form tetraoxaadamantanes at all. Bistetraoxaadamantane derivatives. Cyclic bisdioxine derivative not forming a tetraoxaadamantane due to reduced cavity size. The bisdioxine-calix[6]arene

Quinone-catalyzed oxidative deformylation: synthesis of imines from amino alcohols

• Xinyun Liu,
• Johnny H. Phan,
• Benjamin J. Haugeberg,
• Shrikant S. Londhe and
• Michael D. Clift

Beilstein J. Org. Chem. 2017, 13, 2895–2901, doi:10.3762/bjoc.13.282

• scope of this methodology by employing a range of 1,2-amino alcohol substrates 1 (Table 2). As reported in Table 1, the reaction involving phenylglycinol gave the desired N-PMP imine (7a) in 85% yield (Table 2, entry 1). ortho-Substitution of the arene is reasonably well-tolerated, as 2

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

• visible light irradiation, a first SET reduction of CF3SO2Cl occurred, ultimately leading to the formation of the stabilised trifluoromethyl radical after releasing SO2 and chloride anion. This electron deficient radical was then added on the most electron-rich position of the arene substrate to yield

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

• . In the case of unsymmetrical biaryl substrates, mixtures of regioisomers at C4 and C5 were obtained (Scheme 48). In the reaction mechanism, PIFA played a dual role in the activation of the arene via a π-complex and in the generation of the CF3 radical from CF3SO2Na. More recently, Maruoka and co

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

• (with methyl groups in place of the n-propyl groups at the methylene bridges), an average pKa value as large as 6.3 ± 1 per arene subunit has been estimated from titration curves, under the hypothesis that the four subunits behave equivalently [32]. In the latter case, the deprotonation of phenol groups

• progressive deprotonation, and the consequent presence of an increasing negative charge, are reasonable. It is worth recalling here that the cone conformation of the resorcinarene scaffold is stabilized by the possible formation of a hydrogen-bond network between pairs of phenol groups on adjacent arene units

• , a carbonyl band of fair intensity appears at 1727 cm−1, similar to the one expected for an undissociated carboxylic group. In turn, extensive hydrogen bonding affects the flexibility of the macrocycle scaffold, as well as the possible double free rotation of the arene–CH2–proline single bond–single

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

• "spacers" that electronically insulate the arene ring from the perfluoroalkyl groups, have been previously isolated [17]. As described below, the pursuit of the preceding objectives has met with both success and some unanticipated speed bumps, for which parallel computational studies have provided valuable

• -tagged arene C6H5CH2CH2CH2Rf8 gives a 49.5:50.5 CF3C6F11/toluene partition coefficient. Values for doubly tagged analogs fall into the range (90.7–91.2):(9.3–8.8) (o, m, p-isomers), and that for the triply tagged species 1,3,5-C6H3(CH2CH2CH2Rf8)3 is >99.7:<0.3 [30]. As noted above, longer perfluoroalkyl

• with at least two Rfn substituents per arene ring. Given the ready isolation of the dinitro-substituted aryliodine(III) dichloride II-Me in Scheme 1 [31], this was seen as a surefire objective. However, this was not to be, so the results in this and the following section are presented in inverse

One-pot syntheses of blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones by T3P^® activation of 3-arylpropiolic acids

• Melanie Denißen,
• Alexander Kraus,
• Guido J. Reiss and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2017, 13, 2340–2351, doi:10.3762/bjoc.13.231

• use of phenylpropiolic acid chloride and phenylpropiolic acid as starting materials [45], and as well oxidative arene–alkyne cyclization with dichloro-5,6-dicyano-benzoquinone (DDQ) [46]. Based upon our experience in using propylphosphonic acid anhydride (T3P®) [47] as a condensation agent for in situ

Phosphonic acid: preparation and applications

• Charlotte M. Sevrain,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219

• dendrimers 67 [192]. The use of BrSiMe3 was also applied to diverse organometallic compounds as exemplified in Figure 20. This procedure was applicable to compounds featuring CpFe(CO)2 68 [193] or ferrocenyl 69 [194][195] moieties but also to palladium or platinium pincer complexes 70 [196] or arene–chrome

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

• 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

• receptor. In contrast to the 1,3-disubstituted macrocycle containing two N-(4’-nitrophenyl)acetamide moieties, the 1,2-disubstituted thiacalix[4]arene, which contains only one such fragment and a N,N-diethylacetamide moiety, selectively binds F− anions. Keywords: anion binding; synthesis; thiacalixarenes

• type of anion is needed. (Thia)calix[4]arene derivatives are a favorable platform for the design of such structures [24][25][26][27][28][29][30][31][32][33][34]. Due to their macrocyclic nature and the possibility to modify them in three different ways (upper and lower rims and bridge fragments), they