Solid-state mechanochemical ω-functionalization of poly(ethylene glycol)

• Michael Y. Malca,
• Pierre-Olivier Ferko,
• Tomislav Friščić and
• Audrey Moores

Beilstein J. Org. Chem. 2017, 13, 1963–1968, doi:10.3762/bjoc.13.191

• bromoacyl halides, which introduces unnecessary ester groups instead of direct bromine substitution onto the polymer chain [34][36][37]. Next, we explored the thiolation by milling the mPEG–OTs with NaHS·xH2O for 90 min (Table 2, entries 3 and 4) as reagent, which afforded 1H NMR conversions of 55% and 78

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• and co-workers reported bromination of phenol derivatives, chalcones, 1,3-dicarbonyl compounds using NaBr as bromine source and oxone as oxidant under ball-milling conditions [96]. Within 1 h they could isolate more than 90% of mono or poly-brominated products of phenol and 1,3-dicarbonyl compounds

Accessing simply-substituted 4-hydroxytetrahydroisoquinolines via Pomeranz–Fritsch–Bobbitt reaction with non-activated and moderately-activated systems

• Marco Mottinelli,
• Mathew P. Leese and
• Barry V. L. Potter

Beilstein J. Org. Chem. 2017, 13, 1871–1878, doi:10.3762/bjoc.13.182

• was the only acid able to deliver the desired THIQ 10b. However, in the presence of a deactivating, ortho/para-directing group, such as chlorine (9c) or bromine (9e), HClO4 afforded the desired cyclized product only in the position directed by the substituent. In addition, even HClO4 failed to

A novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines

• Benedikt C. Melzer and
• Franz Bracher

Beilstein J. Org. Chem. 2017, 13, 1564–1571, doi:10.3762/bjoc.13.156

• ) [17], which start with the synthesis of 1-(2-bromoaryl)isoquinolines using Bischler–Napieralski chemistry, followed by tedious replacement of the bromine substituent by cyanide (for modern variants, see ref. [18][19]), and subsequent conversion to a carboxylate and Friedel–Crafts-type cyclization

Direct catalytic arylation of heteroarenes with meso-bromophenyl-substituted porphyrins

• Alexei N. Kiselev,
• Olga K. Grigorova,
• Alexei D. Averin,
• Sergei A. Syrbu,
• Oskar I. Koifman and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2017, 13, 1524–1532, doi:10.3762/bjoc.13.152

• )porphyrinate (2) with a less active bromine atom in the reaction with benzoxazole (Table 1, entry 6). In this case the yield of the coupling product 5 was moderate (45%) though we employed 2 equiv of the heteroarene. The analogous reaction with benzothiazole was unsuccessful. Further we decided to test the

• characterized by two emission bands at 592 and 640–642 nm. All these spectroscopic data demonstrate that the substitution of the bromine atom for heterocyclic moieties does not notably change absorption and emission spectra due to insignificant influence of the electronic properties of the substituents at the

Nitration of 5,11-dihydroindolo[3,2-b]carbazoles and synthetic applications of their nitro-substituted derivatives

• Roman A. Irgashev,
• Nikita A. Kazin,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2017, 13, 1396–1406, doi:10.3762/bjoc.13.136

• , decreasing the reactivity of ICZs 9 towards mild electrophiles. Unlike the formylation reaction, electrophilic bromination of compounds 9a,b has easily taken place on their treatment with bromine, affording dibromo compounds 13a,b. Further transformation of 2,8-dibromo-ICZ 13a into derivative 14a has been

• performed by using the Suzuki–Miyaura cross-coupling reaction with phenylboronic acid under Pd catalysis (Scheme 5). The location of the formyl group and bromine atoms in ICZ derivatives 12 and 13 has been established by X-ray crystallography analysis, performed for single crystals of 12b and 13b (Figure 5

Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds

• M. Fernanda N. N. Carvalho,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122

• carbocyclic five-membered ring to the 2,3-position of the bicyclic camphor-derived moiety (Scheme 2a) [20]. Reactions of 4a with halogens (e.g., bromine) or acids were even more puzzling. In addition to the annulation, an unprecedented formation of a ketone accompanied by the reduction of sulphur took place

Regioselective (thio)carbamoylation of 2,7-di-tert-butylpyrene at the 1-position with iso(thio)cyanates

• Anna Wrona-Piotrowicz,
• Marzena Witalewska,
• Janusz Zakrzewski and
• Anna Makal

Beilstein J. Org. Chem. 2017, 13, 1032–1038, doi:10.3762/bjoc.13.102

• has been reported that nitration and bromination of 2 take place at the 1-position (however, the bromine atom in 1-bromopyrene can migrate into the 4-position in the presence of AlCl3) [8][9], whereas Friedel–Crafts acylation and Vilsmeier formylation take place at the 4-position [10]. We recently

Synthesis and enzymatic ketonization of the 5-(halo)-2-hydroxymuconates and 5-(halo)-2-hydroxy-2,4-pentadienoates

• Tyler M. M. Stack,
• William H. Johnson Jr. and
• Christian P. Whitman

Beilstein J. Org. Chem. 2017, 13, 1022–1031, doi:10.3762/bjoc.13.101

• ]. Ethyl 2-bromocrotonate was synthesized following the protocol for the synthesis of ethyl 2-chlorocrotonate except that liquid bromine was added dropwise under argon in place of chlorine gas [11]. Accordingly, ethyl crotonate (15 g) was dissolved in CH2Cl2 (100 mL), chilled in an ice bath, and a solution

• of bromine (21 g) dissolved in CH2Cl2 (150 mL) was added over a period of 30 min. The solution was allowed to come to ambient temperature overnight. The solvent was removed under reduced pressure and the residue was distilled (3 torr, 79–81 °C) to leave a pale yellow liquid (29.7 g). The 1H and 13C

Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications

• Vinila N. Viswanathan,
• Arun D. Rao,
• Upendra K. Pandey,
• Arul Varman Kesavan and
• Praveen C. Ramamurthy

Beilstein J. Org. Chem. 2017, 13, 863–873, doi:10.3762/bjoc.13.87

• synthesis of monomer M1 started with the cyclization of o-phenylenediamine with thionyl chloride in the presence of triethylamine, a strong base and dichloromethane as the solvent at 0 °C. Compound 1 was then treated with bromine and HBr to obtain 4,7-dibromobenzo[c][1,2,5]thiadiazole (2). The latter

• , 1,2-difluorobenzene was reacted with trimethylsilyl chloride in the presence of lithium diisopropylamide to afford the 1,4-disilylated intermediate 4 and bromination of the latter compound in neat bromine afforded the desired 1,4-dibromo-2,3-difluorobenzene (5). Nitration of 5 by treatment with fuming

Substitution of fluorine in M[C₆F₅BF₃] with organolithium compounds: distinctions between O- and N-nucleophiles

• Anton Yu. Shabalin,
• Nicolay Yu. Adonin and
• Vadim V. Bardin

Beilstein J. Org. Chem. 2017, 13, 703–713, doi:10.3762/bjoc.13.69

• Organoborates M[RBX3] (X = OAlk, F) are widely used in various fields of chemistry [1][2][3][4][5][6][7][8][9][10][11][12]. Their polyfluorinated analogues M[RFBX3] have been used as starting reagents in the synthesis of compounds of hypervalent bromine [13], iodine [14][15][16] and xenon [17][18][19][20][21

N-Propargylamines: versatile building blocks in the construction of thiazole cores

• S. Arshadi,
• E. Vessally,
• L. Edjlali,
• R. Hosseinzadeh-Khanmiri and
• E. Ghorbani-Kalhor

Beilstein J. Org. Chem. 2017, 13, 625–638, doi:10.3762/bjoc.13.61

• -workers developed the synthesis of 5-(dibromomethyl)thiazole derivatives 44 by treatment of N-propargyl thioamides 43 with bromine in an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate). Mechanistically, the reaction involves: i) bromination of triple bond of thioamide 43 which resulted in a

• bridged bromonium ion intermediate A; ii) regioselective 5-exo-dig cyclization of intermediate A to give dihydrothiazole B; and iii) addition of a second bromine to the alkene moiety in intermediate B to provide the corresponding thiazole 44 (Scheme 11) [94]. Recently, Alhalib and Moran reported two

• 4,5-dihydrothiazoles and the competing 6-endo-dig ring-closing process affords 4H-1,3-thiazines after conversion of the charge-transfer complex into the ring-opened iodovinyl B or bridged iodirenium C ions; (2) bromine-mediated cyclizations of both electron-poor and electron-rich N-propargylthioureas

Novel β-cyclodextrin–eosin conjugates

• Gábor Benkovics,
• Damien Afonso,
• András Darcsi,
• Szabolcs Béni,
• Sabrina Conoci,
• Éva Fenyvesi,
• Lajos Szente,
• Milo Malanga and
• Salvatore Sortino

Beilstein J. Org. Chem. 2017, 13, 543–551, doi:10.3762/bjoc.13.52

• dyes were freshly synthesized starting from fluorescein (Flu, 1). Although the described synthetic procedures for the preparation of eosin dyes commonly use Br2, herein the less hazardous N-bromosuccinimide (NBS) was used as the source of bromine. Thus, eosin Y (2) was prepared in a single step from 1

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• interesting bromo reagent for further transformations, has been synthesized from chalcone 128 [67]. In this synthesis, a Nazarov reaction of chalcone 128, in the presence of trifluoroacetic acid, gave 6-methoxy-3-phenyl-1-indanone 129 in 88% yield followed by the reaction with bromine in diethyl ether to give

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

• attempting to elucidate the nature of halogen complexes have emerged since then; however, the structural features of these interactions were unclear until the work of Mulliken who proposed the formation of donor–acceptor complexes [65][66] and Odd Hassel who conducted crystallographic studies of bromine

• complexed with 1,4-dioxane in 1970 [67]. The evidence of the actual bonding were found in these complexes as the O−Br distance in the crystal was about 2.71 Å (Scheme 12), which is 20% smaller than the sum of the van der Waals radii of oxygen and bromine (3.35 Å) while the angle between the O−Br and Br−Br

• − salt of L16 were found to be significantly more reactive than the corresponding TfO− salts. Interestingly, L16 that can potentially form two halogen bonds with the same bromine atom were found to be marginally less active promoters in comparison to compounds L17. Finally, the control experiments ruled

A new protocol for the synthesis of 4,7,12,15-tetrachloro[2.2]paracyclophane

• Donghui Pan,
• Yanbin Wang and
• Guomin Xiao

Beilstein J. Org. Chem. 2016, 12, 2443–2449, doi:10.3762/bjoc.12.237

• also adopted an improved bromination process to prepare 1-(bromomethyl)-2,5-dichloro-4-methylbenzene. Traditionally, there are several disadvantages when molecular bromine is used as a brominating reagent, such as toxicity, inconvenient handling and high reactivity, which lead to unsatisfactory results

• drawbacks such as low atom efficiency and the requirement of reagent residue elimination [14]. In contrast to traditional brominating reagents, the H2O2–HBr system, which generates active bromine in situ, is a convenient and green brominating agent [15]. Furthermore, the use of the H2O2–HBr couple improves

• the selectivity and allows for the complete utilization of bromine atoms, thus increasing the atom economy [16]. These advantages prompted us to develop a novel method to prepare 1-(bromomethyl)-2,5-dichloro-4-methylbenzene and 4,7,12,15-tetrachloro[2.2]paracyclophane in a convenient and green way

Efficient mechanochemical synthesis of regioselective persubstituted cyclodextrins

• Laszlo Jicsinszky,
• Marina Caporaso,
• Katia Martina,
• Emanuela Calcio Gaudino and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2016, 12, 2364–2371, doi:10.3762/bjoc.12.230

• columns, too. The yield increased considerably when bromine derivatives (entries 10 and 11 in Table 1) were used instead of their iodine analogues (entries 7 and 9 in Table 1). An identical TU/Br to TU/I ratio was used in case of 3b and further reduced the yield (entry 8 in Table 1), demonstrating that

• to the known method [13], from freshly dried CDs on a 0.01 mol scale with triphenylphosphine and iodine in DMF. Per-6-bromo-γ-CD (2b’) was prepared in N-methylpyrrolidone by the same method using bromine. Per-6-chloro-β-CD (2a') was synthesized in a similar manner to per-6-iodo-CDs using p

Elongated and substituted triazine-based tricarboxylic acid linkers for MOFs

• Arne Klinkebiel,
• Ole Beyer,
• Barbara Malawko and
• Ulrich Lüning

Beilstein J. Org. Chem. 2016, 12, 2267–2273, doi:10.3762/bjoc.12.219

• ). In order to synthesize the respective methoxy compound 5c, commercially available 3-hydroxybenzoic acid (10) was used as starting material (Figure 6). Bromination introduced a bromine atom into the 4 position (11) [19], then the phenol was turned into its methyl ether. This methylation can be

Determination of the absolute stereostructure of a cyclic azobenzene from the crystal structure of the precursor containing a heavy element

• Reji Thomas and
• Nobuyuki Tamaoki

Beilstein J. Org. Chem. 2016, 12, 2211–2215, doi:10.3762/bjoc.12.212

• elements or chiral internal references. Herein, we report the determination of the absolute stereostructure of the enantiomers of molecule (E)-2, which lacks the possibility of functionalization, using a reverse method, i.e., defunctionalization of its precursor of known stereostructure with bromine

• presence of the bromine substitution in the naphthalene unit gives an added advantage in determining the absolute stereostructure of the separated enantiomers. The determination of the absolute stereostructure of one of the enantiomers of (E)-1 by X-ray diffraction has been presented in our previous report

• enantiomer of (E)-2. According to the Cahn–Ingold–Prelog (CIP) priority rules [51], the absolute configuration of the reduced product should be ‘R’. The priorities of the functional groups on the reduced product reverse on removal of the bromine atom from the parent structure. Comparing the HPLC and CD data

Comparing blends and blocks: Synthesis of partially fluorinated diblock polythiophene copolymers to investigate the thermal stability of optical and morphological properties

• Pierre Boufflet,
• Sebastian Wood,
• Jessica Wade,
• Zhuping Fei,
• Ji-Seon Kim and
• Martin Heeney

Beilstein J. Org. Chem. 2016, 12, 2150–2163, doi:10.3762/bjoc.12.205

• conjugated polymers. In these polymerizations, such as Stille or Suzuki polycondensations, one approach to the block copolymer synthesis is the addition of a well-defined polymeric end-capper, commonly bromine terminated poly(3-hexylthiophene). An issue with this approach can be the formation of a mixture of

DNA functionalization by dynamic chemistry

• Zeynep Kanlidere,
• Oleg Jochim,
• Marta Cal and
• Ulf Diederichsen

Beilstein J. Org. Chem. 2016, 12, 2136–2144, doi:10.3762/bjoc.12.203

• substitution of bromine to the thiol group and finally the introduction of the thiol functional group. The 3-mercaptopropanenitrile (8) was synthesized separately in two steps from acrylonitrile or the 3-chloropropanenitrile according to the previously described procedure [48][49][50]. Next, the obtained

Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties

• Dominik Urselmann,
• Konstantin Deilhof,
• Bernhard Mayer and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2016, 12, 2055–2064, doi:10.3762/bjoc.12.194

• our one-pot bromine-lithium-exchange-borylation-Suzuki (BLEBS) sequence [78], employing an excess of 3,7-dibromo-10-hexyl-10H-phenothiazine (3) [45] as a coupling component in the Suzuki step (Scheme 1). With three bromo-substituted (oligo)phenothiazines 1 in hand the consecutive pseudo five-component

• oligophenothiazines 3 (calculated with the B3LYP functional in vacuo and the 6-311G(d,p) basis set). One-pot bromine-lithium-exchange-borylation-Suzuki (BLEBS) synthesis of 7-bromo-substituted phenothiazines 1b and 1c with 3,7-dibromo-10-hexyl-10H-phenothiazine (2). Pseudo five-component Sonogashira-Glaser

Practical synthetic strategies towards lipophilic 6-iodotetrahydroquinolines and -dihydroquinolines

• David R. Chisholm,
• Garr-Layy Zhou,
• Ehmke Pohl,
• Roy Valentine and
• Andrew Whiting

Beilstein J. Org. Chem. 2016, 12, 1851–1862, doi:10.3762/bjoc.12.174

• bromide 7 was exclusively obtained by addition of 0.95 equivalents of bromine to a solution of 3 in chloroform maintained at −60 °C. However, halogen exchange under literature conditions was sluggish and even after 3 days only around 30% of the starting material had converted [23]. It was theorised that

Synthesis of pyrrolo[2,1-f][1,2,4]triazin-4(3H)-ones: Rearrangement of pyrrolo[1,2-d][1,3,4]oxadiazines and regioselective intramolecular cyclization of 1,2-biscarbamoyl-substituted 1H-pyrroles

• Kkonnip Son and
• Seong Jun Park

Beilstein J. Org. Chem. 2016, 12, 1780–1787, doi:10.3762/bjoc.12.168

• , when PPh3Cl2 was used, triazinones 12 (N-imidoylation product) were more easily obtained than oxadiazines 11 (entries 1 and 4–6, Table 3). In the case of bromine, the O-imidoylation products 11 were preferred over the N-imidoylation products 12, whereas for substrates with 2- and 3-fluorophenyl groups

One-pot synthesis of 4′-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling

• Roman Yu. Peshkov,
• Elena V. Panteleeva,
• Wang Chunyan,
• Evgeny V. Tretyakov and
• Vitalij D. Shteingarts

Beilstein J. Org. Chem. 2016, 12, 1577–1584, doi:10.3762/bjoc.12.153

• , methoxy and phenyl groups, fluorine atoms, and a 1-cyanonaphthalene residue. The variety of ω-substituted alkyl bromides, including an extra bromine atom, a double bond, cyano and ester groups, as well as a 1,3-dioxane fragment are suitable as alkylation reagents. Keywords: alkylcyanobiaryls; cross

• shown by the example of alkylation of anion 3 arising from the sodium salt of 12− and benzonitrile 2a cross-coupling by alkyl bromides 6b–f that were functionalized at their terminal position with a double bond (6b) [33], an extra bromine atom (6c) [34][35], a cyano (6d) or ester group (6e), and a 1,3

• detection of these byproducts indicates that the bromine-containing product 5ac is drawn into consecutive reactions with the anionic forms of 2 as an alkylating reagent and that the rate is comparable or higher than the rate of the interaction of dibromide 6c with anion 3 (compared with [34]). In the case