Identification of optimal fluorescent probes for G-quadruplex nucleic acids through systematic exploration of mono- and distyryl dye libraries

• Xiao Xie,
• Michela Zuffo,
• Marie-Paule Teulade-Fichou and
• Anton Granzhan

Beilstein J. Org. Chem. 2019, 15, 1872–1889, doi:10.3762/bjoc.15.183

• be observed (I/I0 = 40 in the presence of ct DNA and 60 in the presence cl RNA; cf. Figure 6). Conversely, as mentioned above, the dyes containing benzothiophene (1w) or benzofuran (1z, 1þ) residues perform poorly as fluorescent probes. 6) Strongly aggregating dyes (i.e., 1d, 1ð, 10a and 12a

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• regioselectivity of unsymmetrical disubstituted alkynes was not explored. It is important to note the role of DMSO, which acts as a demethylating agent as well as solvent. Even so, the benzothiophene cores constructed by the authors are still valuable, as molecules such as 20b can be further elaborated in many

Recent advances in phosphorescent platinum complexes for organic light-emitting diodes

• Cristina Cebrián and
• Matteo Mauro

Beilstein J. Org. Chem. 2018, 14, 1459–1481, doi:10.3762/bjoc.14.124

• former, a clear impact on the emission colour was observed due to the participation of the cyclometalating unit to the HOMO frontier orbital. Thus, an emission ranging from green to yellow and finally to red was obtained going from phenyl, thiophene and benzothiophene cyclometalating rings, respectively

Fluorogenic PNA probes

• Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

• derivative. 5-Benzothiophene- and 5-benzofuran-modified uracil in aegPNA exhibited a fluorescence that was marginally sensitive to the environment [195]. When incorporated into PNA, benzothiophene-uracil exhibited an increased fluorescence compared to the free nucleoside. The opposite effect was observed

• discrimination between complementary and mismatched duplex observed with benzothiophene-uracil was limited to sequences with flanking Cs. No discrimination was observed with benzofuran-uracil PNA unless it was used in combination with GO as a quencher for ssPNA [196]. In this respect, the thiophene-modified

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

• oxidation as well as the oxidation and deprotonation of the radical benzothiophene precursors are accomplished by a [CoIII] catalyst in a second catalytic cycle. [CoIII] is stepwise reduced to [CoI]. Protonation leads to a [CoIII] hydride complex generating dihydrogen by protonation. Quantitative H2

• respective sulfuranyl radical. Subsequent oxidation closes the catalytic cycle and generates a sulfur-centred cation. Finally, demethylation affords the desired substituted benzothiophene. In 2016, Yuan and co-workers developed a different synthesis of benzothiophenes (Scheme 36) [71]. They found, that a

• radical, which cyclizes to the respective sulfuranyl radical. Oxidation of this intermediate by the radical cation of the superbase closes the electron transfer cycle. Rearomatization of the benzothiophene proceeds via demethylation, accomplished by a hydroxide anion. They were able to perform the

Synthesis and photophysical properties of novel benzophospholo[3,2-b]indole derivatives

• Mio Matsumura,
• Mizuki Yamada,
• Atsuya Muranaka,
• Misae Kanai,
• Naoki Kakusawa,
• Daisuke Hashizume,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2017, 13, 2304–2309, doi:10.3762/bjoc.13.226

• knowledge, the synthesis of benzophosphole-fused indole derivatives as tetracyclic heteroacenes has not been reported. In 2015, Lu et al. reported the synthesis of only one phosphole and indole-fused pentacyclic heteroacene [35]. Recently, we reported simple and efficient synthetic routes to benzothiophene

Synthesis of benzothiophene and indole derivatives through metal-free propargyl–allene rearrangement and allyl migration

• Jinzhong Yao,
• Yajie Xie,
• Lianpeng Zhang,
• Yujin Li and
• Hongwei Zhou

Beilstein J. Org. Chem. 2017, 13, 1866–1870, doi:10.3762/bjoc.13.181

• Jinzhong Yao Yajie Xie Lianpeng Zhang Yujin Li Hongwei Zhou College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, P. R. China 10.3762/bjoc.13.181 Abstract An efficient base-catalyzed protocol for the synthesis of benzothiophene is described. The reaction

• proceeds via base-promoted propargyl–allenyl rearrangement followed by cyclization and allyl migration. Phosphine-substituted indoles can be synthesized by a similar strategy. Keywords: allyl migration; benzothiophene; indole; metal-free; propargyl-allenyl; Introduction Heterocycles are frequently found

• ][14][15]. For example, the preparation of C3-borylated benzothiophene by BCl3-induced borylative cyclization of arylalkynes was recently demonstrated by Ingleson [16]. Allene-mediated cyclization reactions are advantageous due to the convenient preparation of starting materials instead of the use of

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

• isocyanide Pd complex followed by the ring closure [32]; on the other hand, the arylation of benzothiophene in the presence of Pd(OAc)2/PCy3*HBF4/PivOH proceeds in accordance with the concerted metalation–deprotonation mechanism [33][34]. We also investigated the reaction of zinc meso-(3-bromophenyl

A concise and practical stereoselective synthesis of ipragliflozin L-proline

• Shuai Ma,
• Zhenren Liu,
• Jing Pan,
• Shunli Zhang and
• Weicheng Zhou

Beilstein J. Org. Chem. 2017, 13, 1064–1070, doi:10.3762/bjoc.13.105

• 10.3762/bjoc.13.105 Abstract A concise and practical stereoselective synthesis of ipragliflozin L-proline was presented starting from 2-[(5-iodo-2-fluorophenyl)methyl]-1-benzothiophene and 2,3,4,6-tetra-O-pivaloyl-α-D-glucopyranosyl bromide without catalyst via iodine–lithium–zinc exchange. The overall

• key step was the diastereoselective synthesis of pivaloyl-protected 5 (Scheme 2). Thus, this reaction was studied in more detail to screen the best conditions, and the results were presented in Table 1. On the basis of literature [12], 2-[(5-bromo-2-fluorophenyl)methyl]-1-benzothiophene (4b) [9] was

• although it had a high diastereomeric excess (de) value (97%). The main byproduct was the debrominated compound 5” determined by NMR and MS analysis (Table 1, entry 1). The reaction between 2-[(5-iodo-2-fluorophenyl)methyl]-1-benzothiophene (4a) [9] and pivaloyl-protected glycosyl halides 2 were further

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• , carbamate 138, hexahydrobenzothiophene 140 and benzothiophene 142 were converted to the corresponding bisphosphonates 139, 141 and 143, respectively (Scheme 30). The synthesized heterocyclic bisphosphonates showed anti-inflammatory properties. 3 Knoevenagel-induced domino reactions An efficient method into

Pyridylidene ligand facilitates gold-catalyzed oxidative C–H arylation of heterocycles

• Kazuhiro Hata,
• Hideto Ito,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2015, 11, 2737–2746, doi:10.3762/bjoc.11.295

• hereroarenes that has been known to be very sluggish with typical ligand systems [68][69][70][71][72]. In this paper, the C–H arylation reactions of isoxazole, indole, and benzothiophene are presented. In addition, direct observation and isolation of PyC-gold(III) complexes are described. Results and

Efficient synthesis of π-conjugated molecules incorporating fluorinated phenylene units through palladium-catalyzed iterative C(sp²)–H bond arylations

• Fatiha Abdelmalek,
• Fazia Derridj,
• Safia Djebbar,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2015, 11, 2012–2020, doi:10.3762/bjoc.11.218

• -methyl-2-(2,3,4-trifluorophenyl)pyrrole (4) in 91% yield. It is important to note that 4 equiv of N-methylpyrrole were used in order to prevent the formation of the 2,5-diarylated pyrrole as a side product. Finally, both 2-pentylthiophene and benzothiophene were arylated in 76% and 82% yields

• , respectively. Notably, the thiophene derivative was regioselectively arylated at the C4 position and the benzothiophene at the C3 position, which are challenging positions to functionalize using aryl bromides as the coupling partners [58]. Substrates 1–6 contain several reactive C–H bonds in palladium

• was conducted starting from 3-(2,3,4-trifluorophenyl)benzothiophene (6) (Scheme 4, bottom). The first direct arylation, using ethyl 4-bromobenzoate as coupling partner, occurred at the benzothienyl C–H bond to give the C2,C3 diarylated benzothiophene 17 in a good yield of 73%. The second direct

On the mechanism of photocatalytic reactions with eosin Y

• Michal Majek,
• Fabiana Filace and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2014, 10, 981–989, doi:10.3762/bjoc.10.97

• Y-catalyzed phenanthrene synthesis [19] and photoborylation [21] gave similar quantum yields of 0.35 and 0.60, respectively. This suggests that the photocatalytic pathway is indeed populated (Scheme 2, A). Finally, the benzothiophene synthesis [17] and photothiolation [19] exhibited relatively low

Gold(I)-catalyzed domino cyclization for the synthesis of polyaromatic heterocycles

• Mathieu Morin,
• Patrick Levesque and
• Louis Barriault

Beilstein J. Org. Chem. 2013, 9, 2625–2628, doi:10.3762/bjoc.9.297

• benzothiophene 7 was isolated in 89% yield. The formation of this unforeseen product can be explained by the proposed mechanism illustrated in Scheme 2. The gold(I) complexation of alkyne 4 triggers the 5-exo-dig cyclization to produce intermediate 9. At this point, a nucleophilic addition of the thiophene unit

• cyclizations of the enol ether 11a (R1 = p-BrC6H4, R2 = H) gave the corresponding benzothiophene 12a in 83% yield. The use of electron-poor silyl enol ether 11b (R1 = p-NO2C6H4, R2 = H) gave the desired product 12b, albeit in lower yield of 63%. Di- and trisubstituted silyl enol ethers 11c (R1 and R2 = H) and

• , benzothiophene, carbazole and hydrindene in high yields. The use of σ-donor ligands such as IPr (L1) was exceptionally selective for the 5-exo-dig pathway. This Au(I)-catalyzed cyclization occurring in cascade provides a direct access to synthetically useful motifs commonly found in natural products and

Interplay of ortho- with spiro-cyclisation during iminyl radical closures onto arenes and heteroarenes

• Roy T. McBurney and
• John C. Walton

Beilstein J. Org. Chem. 2013, 9, 1083–1092, doi:10.3762/bjoc.9.120

• spectroscopy. Iminyls with suitably placed arene or heteroarene acceptors underwent cyclisations yielding phenanthridine-type products from ortho-additions. For benzofuran and benzothiophene acceptors, spiro-cyclisation predominated at low temperatures, but thermodynamic control ensured ortho-products

• iminyl cyclisations are comparatively slow and, based on the previous product analyses, the ortho- (Ar1-6) mode predominates at room temperature and above. Spiro-cyclisations with benzofuran and benzothiophene acceptors EPR spectra from oxime carbonate 2a, containing a benzofuran acceptor, gave well

• benzothiophene-containing precursor 2b showed a complex spectrum from at least two radicals. A reasonable simulation (see Supporting Information File 1) was obtained as a combination of the spiro-radical 12b (hfs in Table 2) and the solvent-derived adduct 9a. Most likely therefore spiro-cyclisation predominates

N-Heterocyclic carbene–palladium catalysts for the direct arylation of pyrrole derivatives with aryl chlorides

• Ismail Özdemir,
• Nevin Gürbüz,
• Nazan Kaloğlu,
• Öznur Doğan,
• Murat Kaloğlu,
• Christian Bruneau and
• Henri Doucet

Beilstein J. Org. Chem. 2013, 9, 303–312, doi:10.3762/bjoc.9.35

• , benzothiophene [42][45] or arenes [40]. Therefore, we employed carbenes bearing relatively bulky N-substituents. The reaction of Pd(OAc)2 with the corresponding benzimidazolium halides in DMSO at 60–110 °C gave 1–9 in 53–87% yields (Scheme 1). The geometry of these complexes was not defined, as no crystals

Extending the utility of [Pd(NHC)(cinnamyl)Cl] precatalysts: Direct arylation of heterocycles

• Anthony R. Martin,
• Anthony Chartoire,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2012, 8, 1637–1643, doi:10.3762/bjoc.8.187

• observed in 3. With complexes 1–4 in hand, their catalytic activity towards the direct arylation of heteroaromatic compounds was evaluated. For this purpose, the arylation of benzothiophene (6) with 4-bromotoluene (7) was selected as a benchmark reaction (Table 2). This C–H functionalization, initially

• involving a well-defined [Pd(NHC)] complex has been described. However, it is noteworthy that variously substituted benzothiophene cores have been extensively studied in the direct arylation process [4][31][32][33][34][35][36][37]. Initial screening of precatalysts 1–4 was performed with a 2 mol % loading

• starting material. Precatalysts 2 and 4 exhibited closely related activity, with 50 and 49% conversion, respectively. However, complex 3 gave relatively poor conversion of the benzothiophene (6). Thus, selecting 1 as the best precatalyst, the use of other solvents, bases and additives was evaluated to

Synthesis, solid-state fluorescence properties, and computational analysis of novel 2-aminobenzo[4,5]thieno[3,2-d]pyrimidine 5,5-dioxides

• Kenichirou Yokota,
• Masayori Hagimori,
• Naoko Mizuyama,
• Yasuhisa Nishimura,
• Hiroshi Fujito,
• Yasuhiro Shigemitsu and
• Yoshinori Tominaga

Beilstein J. Org. Chem. 2012, 8, 266–274, doi:10.3762/bjoc.8.28

• derivative 3g was obtained from 1a with (S)-methylisothiourea sulfate (2b) in 87% yield (Scheme 2). Fused pyrimidine derivatives 6 and 7 containing the electron-rich heterocycles benzothiophene or benzofuran were prepared by the reaction of ketene dithioacetal 1b or 1c with guanidine carbonate (2a) in 74

Recent advances in direct C–H arylation: Methodology, selectivity and mechanism in oxazole series

• Cécile Verrier,
• Pierrik Lassalas,
• Laure Théveau,
• Guy Quéguiner,
• François Trécourt,
• Francis Marsais and
• Christophe Hoarau

Beilstein J. Org. Chem. 2011, 7, 1584–1601, doi:10.3762/bjoc.7.187

• oxazoles with benzothiophene [83]; (c) Cu(II)-catalyzed direct cross-coupling of (benz)oxazole with arenes [84].

The efficient synthesis of dibenzo[d,d′]benzo[1,2-b:4,3-b′]dithiophene and cyclopenta[1,2-b:4,3-b′]bis(benzo[d]thiophen)-6-one

• Zhihua Wang,
• Sheng Zhu,
• Jianwu Shi and
• Hua Wang

Beilstein J. Org. Chem. 2009, 5, No. 55, doi:10.3762/bjoc.5.55

• fabricate organic field-effect transistors (OFETs) [1][2][3][4][5][6][7], light emitting diodes (LEDs) [8][9], and photovoltaic cells [10]. Various novel π-extended heteroarenes, e.g. dibenzo[d,d′]thieno[3,2-b:4,5-b′]dithiophene [11], pentathienoacene [12], and benzo[1,2-b:4,5-b′]bis[b]benzothiophene [13

• nm and 380 nm. Both 1 and 2 possess molecular connectivities of cross-conjugated π-system that shows π-electron delocalization with helical distortion. Conclusion Derivatives of benzothiophene, thienothiophene, and thienodithiophene with good characteristics for OFETs were recently reported [5][6][7

Transition- metal/Lewis acid free synthesis of acyl benzothiophenes via C-C bond forming reaction

• Sarbani Pal,
• Mohammad Ashrafuddin Khan,
• P. Bindu and
• P. K. Dubey

Beilstein J. Org. Chem. 2007, 3, No. 35, doi:10.1186/1860-5397-3-35

• - and 3-acyl substituted benzothiophenes has been described via environmentally benign acylation of benzothiophene with in situ generated acyl trifluoroacetates. Both aliphatic and aromatic carboxylic acids participated in trifluoroacetic anhydride/phosphoric acid mediated C-C bond forming reactions

• under solvent-free conditions affording acyl benzothiophenes in good overall yields. Background Benzothiophene derivatives possessing an acyl group as one of the substituents on the five-membered ring are of immense medicinal value because of their promising pharmacological properties. For example

• the chronic treatment of thrombotic disorders.[3] Apart from medicinal interest, acyl derivatives of benzothiophene have synthetic value and a variety of diversity based benzothiophene derivatives have been prepared using these compounds. [4][5][6][7][8][9][10][11][12] While a number of methods are