A toolbox of molecular photoswitches to modulate the CXCR3 chemokine receptor with light

• Xavier Gómez-Santacana,
• Sabrina M. de Munnik,
• Tamara A. M. Mocking,
• Niels J. Hauwert,
• Shanliang Sun,
• Prashanna Vijayachandran,
• Iwan J. P. de Esch,
• Henry F. Vischer,
• Maikel Wijtmans and
• Rob Leurs

Beilstein J. Org. Chem. 2019, 15, 2509–2523, doi:10.3762/bjoc.15.244

• angle of the biaryl moiety of 1e was speculated to be associated with its agonist activity (vide supra) [24]. The alignment of the cis-isomer of 2a with agonist 1e is very different. The outer aromatic ring of cis-2a goes out of plane and is now occupying the space that is also occupied by the iodine

• comparable to the first series (3b–e) were prepared. Moreover, since the importance of the presence of a halogen in the outer ring was suggested in 2, compounds 3f–h, which include an iodine atom on the ortho, meta and para-positions, respectively, were synthesized. The synthesis of compounds 3a–e was

• overall yields similar to the ones obtained for 2a–e. However, 2-iodonitrosobenzene cannot be accessed through oxidation of the corresponding aniline owing to oxidation sensitivity of the iodine atom. Therefore, an alternative route had to be used to synthesize 3f–h (Scheme 2). The route began with the

Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms

• A. Lennart Schleper,
• Mariano L. Bossi,
• Vladimir N. Belov and
• Stefan W. Hell

Beilstein J. Org. Chem. 2019, 15, 2344–2354, doi:10.3762/bjoc.15.227

• good yields by treatment of 3 with elemental iodine and periodic acid in aqueous acetic acid with addition of sulfuric acid, and by treatment of 6 with elemental iodine and periodic acid in concentrated sulfuric acid, respectively. The conditions for monoiodination of 6 have been published recently [5

• ]. We observed that the reproducible monoiodination of DAE 3 to form compound 4 was possible under similar conditions and in low yield (14%) by using smaller amounts of periodic acid (0.34 equiv) and iodine (0.68 equiv) than the amounts of these reagents used for diiodination (see Experimental for

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

• stability with reactivity in a model oxygenation. Keywords: differential scanning calorimetry; hypervalent iodine; N-heterocycle; stability; thermogravimetry; Introduction Hypervalent iodine compounds, in particular aryl-λ3-iodanes, have found wide spread applications as oxidants and electrophilic group

• transfer reagents in organic synthesis [1][2][3][4][5][6][7][8][9][10][11]. A 3-center 4-electron bond connects the central iodine atom, providing two electrons, with two carbon- or heteroatom ligands L1 and L2, providing one electron each (Figure 1). These ligands can be arranged along the hypervalent

• iodine atom through an open-chained, a pseudocyclic or a cyclic structure. One of the ligands gets either substituted during an iodane-mediated transformation or is directly transferred in an electrophilic group-transfer reaction onto a nucleophilic substrate. The other ligand stabilizes the

Functionalization of 4-bromobenzo[c][2,7]naphthyridine via regioselective direct ring metalation. A novel approach to analogues of pyridoacridine alkaloids

• Benedikt C. Melzer,
• Alois Plodek and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2304–2310, doi:10.3762/bjoc.15.222

• the iodine quenching product 13), as D2O quenching of metalated arenes obtained with amide bases do not necessarily give complete deuteration. A hydrogen-bonded complex between the metalated species and TMP is postulated to undergo partial H/D exchange reactions with D2O before quenching takes place

• [25]. The reaction of metalated 9d with diverse electrophiles was tested in further studies. Quenching with iodine gave 5-iodo derivative 13 in a good yield of 71%. As the group of Knochel could demonstrate [26] that the closely related substrate 1-chloro-4-iodo-2,7-naphthyridine undergoes consecutive

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

• fluoride source and PhI(OPiv)2 as a hypervalent iodine oxidant (Scheme 8). Very recently, they [44] optimized this transformation and achieved the benzylic C–H radiofluorination with no-carrier-added Ag[18F]F. This method was applied to the radiolabeling of diversely substituted 8-methylquinoline

• ] 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

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

• Christoph W. Grathwol,
• Nathalie Wössner,
• Sören Swyter,
• Adam C. Smith,
• Enrico Tapavicza,
• Robert K. Hofstetter,
• Anja Bodtke,
• Manfred Jung and
• Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

• resemble a fixed (Z)-configuration of the stilbene double bond. Therefore, comparison with 2b could provide information concerning differential biological activity of the two photoisomers. By applying Mallory reaction conditions to a solution of 2b in methanol utilizing oxygen and iodine as oxidants we

• from Acros Organics. Thin-layer chromatography (TLC) was executed on silica gel 60 F254 aluminium plates purchased from Merck. Visualization of the compounds was accomplished by UV-light (254 nm and 366 nm) and by staining with iodine, DNPH/H2SO4 (2 g 2,4-dinitrophenylhydrazine and 5 mL H2SO4 in 50 mL

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• (iodine, bromine) and chalcogens (selenium and tellurium) [18]. While there are several strategies for the synthesis of triazoles, the Cu(II)-catalyzed azide–alkyne cycloaddition reaction (CuAAC click reaction) is considered as one of the most efficient, simple and mild approaches towards the preparation

• highly functionalized 1,2,3-triazolium macrocycles under optimized reaction conditions, although cyclizations also have been carried out starting from triazolium building blocks (Figure 2). Using a small variation in the reaction protocols of the click reaction, iodine atoms can be introduced at the 5

1,2,3,4-Tetrahydro-1,4,5,8-tetraazaanthracene revisited: properties and structural evidence of aromaticity loss

• Arnault Heynderickx,
• Sébastien Nénon,
• Olivier Siri,
• Vladimir Lokshin and
• Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2019, 15, 2059–2068, doi:10.3762/bjoc.15.203

• : infinite chains of the N–H···N=C shortened distances (N(2)···N(3) distance 3.047 Å, (Figure 11). The iodine anions are not involved in the intermolecular interactions. Conclusion Unlike previously described, 1,2,3,4-tetrahydro-1,4,5,8-tetraazaanthracene (3) is a thermally stable compound and can be

• benzene ring are given in red. The ORTEP view of 6a. Torsion angles within the benzene ring are given in red. The ORTEP view of 7a (the iodine counter anion has been omitted for clarity). Torsion angles within the benzene ring are given in red. Normalized absorption spectra of 3 in: toluene (black

• : nitrogen, blue; carbon, grey; iodine, violet. Synthesis of THTTA (3). Protonation, alkylation and acylation of 3. Charge transfer and delocalization within 3 and its diprotonated (6a) and monomethylated (7a) derivatives. Experimental and calculated selected bond lengths (Å). Supporting Information

Fluorinated azobenzenes as supramolecular halogen-bonding building blocks

• Esther Nieland,
• Oliver Weingart and
• Bernd M. Schmidt

Beilstein J. Org. Chem. 2019, 15, 2013–2019, doi:10.3762/bjoc.15.197

• , Universitätsstraße 1, D-40225 Düsseldorf, Germany 10.3762/bjoc.15.197 Abstract ortho-Fluoroazobenzenes are a remarkable example of bistable photoswitches, addressable by visible light. Symmetrical, highly fluorinated azobenzenes bearing an iodine substituent in para-position were shown to be suitable supramolecular

• significantly strengthened in solution. However, the bathochromic shift of the π→π* band leads to a partial overlap with the n→π* band, making it slightly more difficult to address. The introduction of iodine substituents is furthermore accompanied with a diminishing thermal half-life. A series of three

• calculated the molecular electrostatic potentials of the halogen bond donors A1–3 to visualize their capabilities to form halogen bonded architectures (Figure 1). Looking at the electrostatic surface potentials of the halogen bond donors, one can see that A3 shows a maximum value on the iodine atom that is

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• application in DSSCs, in rather good agreement with the values obtained from DFT calculations. Finally, we report preliminary results employing these molecules as photosensitizers in dye solar cells with iodine-based liquid electrolytes. We show that the limited performances of these new BODIPY derivatives

• 0.15 eV (neglecting entropy changes during the light absorption) is required to efficiently inject photo excited electrons from the LUMO of the dyes in the CB of the oxide [34]. Usually iodine-based liquid electrolytes are comprising additives such as tert-butylpyridine (tBP) which is known to shift

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• of iodine in the absence of copper did not result in the desired product keeping the reaction conditions intact. However, based on control experiments and the works of Zhang and Ma’s group [103][104], oxidative C–H functionalization was expected to be more likely involved in the cyclization strategy

• ) [119]. In this reaction, iodine promoted the formation of iodo-intermediate 98 with a carbonyl compound that underwent nucleophilic substitution with 2-AP 3. CuO played multiple roles in this reaction. Firstly it acts as an oxidizing agent to convert molecular iodine to the reactive iodonium ion (I

• +) species, secondly as a weak base to neutralize HI and next to reoxidize the iodide ion (I−) to molecular iodine (I2, Scheme 33). The reaction has enjoyed a broad substrate scope including arylmethyl, heteroaryl, α,β-unsaturated methyl ketones, β-ketone esters and 2-APs-substituted with EW and EDGs. The

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

A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

• András György Németh,
• György Miklós Keserű and
• Péter Ábrányi-Balogh

Beilstein J. Org. Chem. 2019, 15, 1523–1533, doi:10.3762/bjoc.15.155

• , we have turned our attention to different benzylic alcohols that could be utilized to further examine the functional group tolerance of the reaction. Notably, chlorine, bromine and iodine substituents were compatible with the transformation, providing 3m, 3n, 3r and 3s in 81–89% yield. The nitrile

Selenophene-containing heterotriacenes by a C–Se coupling/cyclization reaction

• Pierre-Olivier Schwartz,
• Sebastian Förtsch,
• Astrid Vogt,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2019, 15, 1379–1393, doi:10.3762/bjoc.15.138

• dehydrocoupling with ZnCl2 and CuCl2. Selenophene precursor 10 itself was readily obtained in 68% yield from selenophene (9) in a one-pot procedure by successive lithiation with n-BuLi and quenching with trimethylsilyl chloride and iodine, respectively. We reacted biselenophene 11 with K2S as sulfur source and

• B3LYP and CAMB3LYP functional and 6-31++(d,p) basis-set [56]. Materials Iodine, zinc(II) chloride, copper(II) chloride, potassium hydroxide, chlorotrimethylsilane, copper(I) iodide, and potassium phosphate were purchased from Merck. Diisopropylamine, bis(dibenzylideneacetone)palladium(0

• was stirred at −78 °C for 45 min. Chlorotrimethylsilane (2 mL, 16 mmol) was added and the mixture was stirred for one more hour. Then, another portion of n-BuLi (1.6 M, 10 mL, 16 mmol) was added. After stirring for one hour at −78 °C, a solution of elemental iodine (3.8 g, 15 mmol) in THF (8 mL) was

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks

• Sebastian Hamer,
• Fynn Röhricht,
• Marius Jakoby,
• Ian A. Howard,
• Xianghui Zhang,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132

• [43]. The synthesis of linker 1 was straightforward (Scheme 2). The core unit was synthesized by simple di-iodination of commercially available 1,2-difluorobenzene (6). The lithiation and subsequent metal iodine exchange has already been described in the literature [44][45][46]. While in known

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• giving the ring A-fused pyridine at positions 2 and 3. This iodine-promoted MCR tolerates both electron-donating and electron-withdrawing groups on the aromatic aldehyde, thus leading to varied, optically active asphaltene model compounds that could serve as structural mimetics of known components of

Electrophilic oligodeoxynucleotide synthesis using dM-Dmoc for amino protection

• Shahien Shahsavari,
• Dhananjani N. A. M. Eriyagama,
• Bhaskar Halami,
• Vagarshak Begoyan,
• Marina Tanasova,
• Jinsen Chen and
• Shiyue Fang

Beilstein J. Org. Chem. 2019, 15, 1116–1128, doi:10.3762/bjoc.15.108

• not caused by premature oxidation of the dM-Dmoc groups by iodine in the oxidation step in ODN synthesis because the problem did not exist when Dmoc was used for ODN synthesis [41]. In addition, we also subjected 1,3-dithiane to the iodine oxidation conditions for over 24 hours, no oxidation could be

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

• of 9, followed by an intramolecular cyclic amide formation, would produce isoindolinone derivatives 4. Employing benzoic acids 10 ortho-substituted with iodine along with alkynylcarboxylic acids 11 and ammonium acetate (12), in the presence of caesium carbonate and copper iodide as catalyst (10%), a

Novel (2-amino-4-arylimidazolyl)propanoic acids and pyrrolo[1,2-c]imidazoles via the domino reactions of 2-amino-4-arylimidazoles with carbonyl and methylene active compounds

• Victoria V. Lipson,
• Tetiana L. Pavlovska,
• Nataliya V. Svetlichnaya,
• Anna A. Poryvai,
• Nikolay Yu. Gorobets,
• Erik V. Van der Eycken,
• Irina S. Konovalova,
• Svetlana V. Shiskina,
• Alexander V. Borisov,
• Vladimir I. Musatov and
• Alexander V. Mazepa

Beilstein J. Org. Chem. 2019, 15, 1032–1045, doi:10.3762/bjoc.15.101

• -3000. The progress of reactions and the purity of the obtained compounds were monitored by TLC on Silufol UV-254 plates in EtOAc/CH2Cl2 (1:4) and visualized under UV light or iodine fume. General procedure for the synthesis of 5-((2-amino-4-aryl-1H-imidazol-5-yl)(aryl)methyl)-6-hydroxy-2,2-dimethyl-4H

Heck- and Suzuki-coupling approaches to novel hydroquinone inhibitors of calcium ATPase

• Robert J. Kempton,
• Taylor A. Kidd-Kautz,
• Soizic Laurenceau and
• Stefan Paula

Beilstein J. Org. Chem. 2019, 15, 971–975, doi:10.3762/bjoc.15.94

• 4b from 1,4-dimethoxybenzene, among them iodine in the presence of trichlorocyanuric acid and silica gel [9], I2/periodic acid [10], I2/silfen [11], N-iodosuccinimide [12], and potassium iodide/potassium iodate [13]. In our hands the best yields of 4b were obtained using iodine in the presence of

Halogen bonding and host–guest chemistry between N-alkylammonium resorcinarene halides, diiodoperfluorobutane and neutral guests

• Fangfang Pan,
• Mohadeseh Dashti,
• Michael R. Reynolds,
• Kari Rissanen,
• John F. Trant and
• Ngong Kodiah Beyeh

Beilstein J. Org. Chem. 2019, 15, 947–954, doi:10.3762/bjoc.15.91

• ·DIOFB·MeOH and 1·DIOFB·MeCN, Figure 5). Minimal changes (<0.03 ppm) were observed for the fluorine atoms attached to the internal carbon atoms. This strongly suggests that a similar XB involving the iodine atoms of DIOFB exists in solution both with and without the guests (Figure 5). To complement the direct

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• exothermic reactions between amines and iodine(III) [114]. By this process undirected C(sp3)–H bonds were shown to be functionalized for dehydrogenative imination reactions. Overall, at 1,5-distances (remote) a dehydrogenative and intramolecular C(sp3)–H imination by 4H elimination was readily done via

• the iodine(III) environment. Conclusion Over the last years, substantial progress has been made in the area of mechanochemistry as environmentally benign method in organic synthesis, materials science and supramolecular chemistry. In this review the major focus has been to cover the concept and

• (pyridin-4-yl)ethylene and 4,6-dichlororesorcinol. Halogen-bonded co-crystals via a) I···P, b) I···As, and c) I···Sb bonds [112]. Transformation of contact-explosive primary amines and iodine(III) into a successful chemical reaction for amide synthesis. Undirected C–H functionalization by using the acidic

Strong hyperconjugative interactions limit solvent and substituent influence on conformational equilibrium: the case of cis-2-halocyclohexylamines

• Camila B. Francisco,
• Cleverton S. Fernandes,
• Ulisses Z. de Melo,
• Roberto Rittner,
• Gisele F. Gauze and
• Ernani A. Basso

Beilstein J. Org. Chem. 2019, 15, 818–829, doi:10.3762/bjoc.15.79

• function LanL2DZ-ECP was employed for the iodine atom. Solvation calculations were performed in dichloromethane and methanol, with the the implicit model IEF-PCM and the description of the molecular cavity through Bondi’s atomic radii. Molecular Mechanics calculations were performed using the software

Homo- and hetero-difunctionalized β-cyclodextrins: Short direct synthesis in gram scale and analysis of regiochemistry

• Gábor Benkovics,
• Mihály Bálint,
• Éva Fenyvesi,
• Erzsébet Varga,
• Szabolcs Béni,
• Konstantina Yannakopoulou and
• Milo Malanga

Beilstein J. Org. Chem. 2019, 15, 710–720, doi:10.3762/bjoc.15.66

• ditosylation reactions and for the observed partial regioselectivity in reaction 2 (Scheme 2). Additionally, a Vilsmeier–Haack/Appel-type iodination reaction was performed with β-CD, using triphenylphosphine (PPh3) and iodine (I2) in DMF (reaction 3, Scheme 2). This reaction is known to be selective for the

• area percentage ratio 52:48, respectively (reaction 3, Scheme 2). This outcome might be attributed to the bulkiness of the halogenating agent (triphenylphosphine–iodine adduct) and to the mild reaction conditions used (i.e., a relatively low temperature for the iodination), under which the substitution

Synthesis of 2H-furo[2,3-c]pyrazole ring systems through silver(I) ion-mediated ring-closure reaction

• Vaida Milišiūnaitė,
• Rūta Paulavičiūtė,
• Eglė Arbačiauskienė,
• Vytas Martynaitis,
• Wolfgang Holzer and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2019, 15, 679–684, doi:10.3762/bjoc.15.62

• fluorescent organic nanoparticles [31][32][33][34]. The iodination of 1 with iodine in the presence of KOH in DMF afforded 4-iodo-1H-pyrazol-3-ol 2 [26]. We have previously shown that the Sonogashira-type coupling of the aforementioned iodinated compound with phenylacetylene under standard reaction conditions

• -furo[2,3-c]pyrazoles starting from commercially available 1-phenylpyrazol-3-ol. Iodination of the latter compound with iodine in DMF smoothly afforded 1-phenyl-4-iodopyrazol-3-ol, which can undergo a Pd-catalyzed coupling with terminal alkynes to give the corresponding 4-alkynyl-3-hydroxy-1-phenyl-1H