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