First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

• Grzegorz Mlostoń,
• Katarzyna Urbaniak,
• Paweł Urbaniak,
• Anna Marko,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156

• centrosymmetric, the compound in the crystal is racemic. The S-atom of the thiophene ring is disordered over two unequally occupied positions as a result of slight but opposite directions of envelope puckering of the ring. The hydroxy group forms an intramolecular hydrogen bond with the adjacent quinoid O-atom

• (for C26H20O2S): 395 (100, [M − 1]−). ORTEP plot [29] of the molecular structure of 4k showing the major conformation of the disordered thiophene ring (50% probability ellipsoids; arbitrary numbering of the atoms). Products of the reactions of thiochalcones 1a and 1b with 1,4-benzoquinone (2a) and of

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

• Jiang has very recently described a complementary method for the synthesis of carbazoles by combining cyclic diaryl-λ3-iodanes with sodium azide in the presence of copper(I) thiophene-2-carboxylate (CuTc) and triphenylphosphine. The reaction affords the expected of N–H free derivatives 63 in moderate to

• been further extended to the synthesis of a new series of molecules 77, where the central thiophene moiety is replaced by a 6-membered heterocycle, which is substituted by a gem-dimethyl or a cyclopropyl group. In this case, the reaction can be performed under metal-free conditions in the presence of a

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

• , together with the use of heterocyclic moieties such as thiophene or carbazole, clearly favours the luminescence properties of these type of platinum(II) complexes [68]. As aforementioned, N-deprotonable azole units constitute a compelling alternative to C-cyclometalating ligands [16]. In this regard

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

• thiophene, cyclopentene and adamantyl derivatives 30a–c with good AE values (51% for 30a). The proposed mechanism involves two distinct catalytic cycles for the amination and the arylation reaction step (Scheme 17). First, a metallanitrene B is formed via the reaction of the (dicarboxyiodo)benzene 20 with

Synthesis of pyrazolopyrimidinones using a “one-pot” approach under microwave irradiation

• Mark Kelada,
• John M. D. Walsh,
• Robert W. Devine,
• Patrick McArdle and
• John C. Stephens

Beilstein J. Org. Chem. 2018, 14, 1222–1228, doi:10.3762/bjoc.14.104

•  1). The heterocyclic furan and thiophene substituents allowed generation of the desired 5-aminopyrazoles in 75% and 81% yields, respectively (Scheme 1). Alkyl groups appeared to be less well tolerated, where the corresponding alkyl-substituted 5-aminopyrazoles were isolated in lower yields. With a

Rapid transformation of sulfinate salts into sulfonates promoted by a hypervalent iodine(III) reagent

• Elsa Deruer,
• Vincent Hamel,
• Samuel Blais and
• Sylvain Canesi

Beilstein J. Org. Chem. 2018, 14, 1203–1207, doi:10.3762/bjoc.14.101

• such as thiophene or anisole. It should be stressed that the formation of substituted aromatic systems through a Friedel–Crafts type process [36] is an argument in favor of the formation of the electrophilic sulfonium species 3 (Scheme 1). In the presence of thiophene, compounds 9 were obtained in 23

• 10a. If anisole was used instead of thiophene an expected mixture of compounds 11a and 11b was observed in a ratio 1:1 and in a low yield of 14%. So far, the yields observed with carbon-based nucleophiles have been low, but they clearly demonstrate the feasibility of this approach. Further

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

• , thereby reducing strength of electrostatic interactions between the ligands with DNA phosphate backbone [120]. Wilson et al. rationally designed benzimidazole derivatives by keeping pre-organized N-methylbenzimidazole (N-MeBI)-thiophene as central fragment (conjugates 55 and 56, Figure 10) in order to

• selectively bind mixed G·C and A·T sequences of DNA. They hypothesized that thiophene (positive electrostatic potential) and the electron-donor nitrogen of N-MeBI should pre-organize the conformation for accepting hydrogen bond from G-NH2, which was validated by replacing the thiophene moiety with other

• heterocyclic rings such as furan 62 and 63 [126], thiophene 64 [127] and pyridine 65 (Figure 11) [128]. These conjugates exhibit potent antibacterial and antiprotozoal activity with much reduced toxicity. It was further concluded that π-stacking, H-bonding with the floor of the minor groove along with

Hypervalent iodine-guided electrophilic substitution: para-selective substitution across aryl iodonium compounds with benzyl groups

• Cyrus Mowdawalla,
• Faiz Ahmed,
• Tian Li,
• Kiet Pham,
• Loma Dave,
• Grace Kim and
• I. F. Dempsey Hyatt

Beilstein J. Org. Chem. 2018, 14, 1039–1045, doi:10.3762/bjoc.14.91

• donation is also demonstrated in the thiophene (1j) group tested (Table 2, entry 9). In the case of electron-withdrawing groups, deactivation occurs and the only reaction is the decomposition of the I(III) to I(I) (Table 2, entries 10 and 11). The fact that no product was formed when using electron

Fluorogenic PNA probes

• Tirayut Vilaivan

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

• 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

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

• those of others. Keywords: 5-(heterocyclic)thiophenes; one-pot sequential synthesis; sulfur ylide; tetrasubstituted thiophene; Introduction Since the discovery of stable sulfonium ylides 1 in 1930 [1] and the pioneering work of several research groups during the 1960s (2 and 3) [2][3][4][5][6][7][8][9

• and 2B), Al-Showiman and co-workers reported a trisubstituted 5-(pyridin-2-yl)thiophene, obtained from the reaction of 5-(enaminone)thiophene with 2,4-pentanedione in glacial acetic acid in the presence of ammonium acetate [54][55]. Ila and co-workers reported the synthesis of tri- and

• yield (32%). Starting from malonitrile, compound 8an was also prepared in a moderate yield (50%) via a Thorpe–Ziegler-type cyclization of N,S-acetal 7an. In this case, the intramolecular cyclization reaction was carried out at 100 °C for 3 h. With 5,5-dimethylcyclohexane-1,3-dione, thiophene 8ao was

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

• -catalyzed synthesis of vinyl sulfones. In addition to aryl sulfinate salts, also alkyl and heteroaryl sulfinate salts were applied in the reported method (Scheme 42a) [78]. Short aliphatic alkyl chains as well as sterically demanding cyclohexyl or 10-camphor sulfinate salts and substituted 2-thiophene

• well as one thiophene derivative. Formation of other sulfone derivatives The groups of Yang and Wang reported in 2016, that β-ketosulfones can be obtained by direct visible-light induced oxysulfonylation of styrenes, applying similar photoredox conditions as reported by Wang and co-workers [81] one

• arenes react well and substituted pyrroles and indoles give the corresponding sulfoxides in high yields. Less electron-rich thiophene or benzene derivatives gave low yields. Nevertheless, carbocyclic azulene afforded the respective sulfoxide in 88% yield. We propose an electrophilic aromatic substitution

Reactivity of bromoselenophenes in palladium-catalyzed direct arylations

• Aymen Skhiri,
• Ridha Ben Salem,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2017, 13, 2862–2868, doi:10.3762/bjoc.13.278

• employed to prepare 2-heteroarylated selenophenes; whereas, 2,5-dibromoselenophene generally gave 2,5-di(heteroarylated) selenophenes in high yields using both thiazole and thiophene derivatives. Moreover, sequential catalytic C2 heteroarylation, bromination, catalytic C5 arylation reactions allowed the

• heteroarenes in the presence of 2 mol % Pd(OAc)2, KOAc as the base in DMA at 90 °C (Scheme 2). The reaction of 2-isopropyl-4-methylthiazole gave the desired product 2 in 82% yield. Conversely, low yields in the target products 3–5 were obtained for the reactions with thiophene-2-carbonitrile, 2-chlorothiophene

• and 2-pentylthiophene, although complete conversions of 2-bromoselenophene were observed. A similar result was obtained for the reaction with 1-phenylpyrrole. Reactions performed at a higher temperature with thiophene-2-carbonitrile, 2-chlorothiophene afforded 3 and 4 in slightly lower yields

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

• , pyrimidine, thiophene, etc. the Maiti group reported an alternative approach toward α-trifluoromethyl ketones starting from (hetero)arylacetylenes 7 and also aliphatic terminal alkynes 8 (Scheme 5) [24]. The trifluoromethyl radical was generated from CF3SO2Na as indicated earlier, oxygen from air was the

Rh(II)-mediated domino [4 + 1]-annulation of α-cyanothioacetamides using diazoesters: A new entry for the synthesis of multisubstituted thiophenes

• Jury J. Medvedev,
• Ilya V. Efimov,
• Yuri M. Shafran,
• Vitaliy V. Suslonov,
• Vasiliy A. Bakulev and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2017, 13, 2569–2576, doi:10.3762/bjoc.13.253

• reactions of acyclic diazoesters with α-cyanothioacetamides. It provides a way for the preparation of 5-amino-3-(alkoxycarbonylamino)thiophene-2-carboxylates, 2-(5-amino-2-methoxycarbonylthiophene-3-yl)aminomalonates and (2-cyano-5-aminothiophene-3-yl)carbamates with the preparative yields of up to 67%. It

• . The same reaction with 2a in toluene solution (reflux at 110 °C) instead of benzene lead to a decrease of the yield of thiophene 3a (to 38%) in favour of thiophene 4a (42%, Table 1, entry 2). However, even under these fairly severe conditions, it took from 3 to 6 h to achieve a complete conversion of

• of thiophene 4a (up to 32%), though the total yield of the main reaction products 3a + 4a therewith decreased to 53% (Table 1, entry 5). Replacing diazomalonate 2a by diethyl diazomalonate (2b) did not essentially change the yields of the main products, 3a’ and 4a’ (44 and 20%, respectively; Table 1

Structure–property relationships and third-order nonlinearities in diketopyrrolopyrrole based D–π–A–π–D molecules

• Jan Podlesný,
• Lenka Dokládalová,
• Oldřich Pytela,
• Adam Urbanec,
• Milan Klikar,
• Numan Almonasy,
• Tomáš Mikysek,
• Jaroslav Jedryka,
• Iwan V. Kityk and
• Filip Bureš

Beilstein J. Org. Chem. 2017, 13, 2374–2384, doi:10.3762/bjoc.13.235

• -photon absorbers (2PA). In this respect, the central DPP bicyclic lactam is often decorated with electron donors such as alkoxy- or dialkylamino groups [11][12], triphenylamine [13][14], heterocyclic carbazole [15], thiophene [16][17], furan [18], and organometallic ferrocene [19]. 2PA-active DPPs were

• report herein the systematic modification of the 3,6-dithienyl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione central acceptor with N,N-dimethylanilino (DMA), methoxyphenyl, thiophene, methoxythiophene, and ferrocene peripheral electron donors (Figure 1). Fundamental properties of D–π–A–π–D chromophores 1–5

• and its final cross-coupling reactions (Scheme 1). The construction of the DPP central scaffold 6 was accomplished by a well-known reaction between thiophene-2-carbonitrile and dimethyl succinate in the presence of sodium tert-amylalcoholate generated in situ [32]. The reaction provided 6 with a high

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• substituents were formed. Polycyclic products 35 were prepared through a concerted [4 + 2]-cycloaddition of E-1a with thiophene-functionalized fulvenes 36 [42] (Scheme 12). These cycloadducts are reported to undergo reversible intramolecular photocyclization to give products of type 37. The formation of the

• thiophene derived sulfur ylide 12. Cyclopropanation of dimethyl dicyanofumarate (E-1b) through a stepwise reaction with the in situ generated thiocarbonyl S-isopropanide 16a. The [2 + 2]-cycloadditions of dimethyl dicyanofumarate (E-1b) with electron-rich ethylenes 20 and 22. The [2 + 2]-cycloaddition of

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

• the transformation of phosphonates under acidic conditions. As an illustration, the thiophene diphosphonic acid 49 [173], the pyridine oxide 50 [179], the furane phosphonic acid 51 [174], the bipyridine bis thiophene phosphonic acid 52 [180] or the α-aminophosphonic acid 53 that was assessed as

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

• ]. Mechanochemical methods of the Mannich reaction, Paal–Knorr synthesis, Bigineli reaction, Hantzsch reaction, and syntheses of substituted pyran, thiophene, isoquinoline derivatives, etc. are also reported [104][107][112][113]. Isocyanide-based multi-component reactions are also well known [114][115]. Recently, in

• the sole products. Contrastingly, in the solution of acetonitrile imines of benzaldehyde and amines were formed preferably. Different aromatic or heteroaromatic aldehydes including thiophene carboxaldehyde, pyridine carboxaldehyde and cyclohexyl carboxaldehyde as well as various amines like morpholine

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

• heterocycles are not well-documented [30][31]. Recently, our group explored the utilization of β-sulfonium carbanions for the preparation of thiophene derivatives [19]. Alkynes were treated with acyl chloride under Sonogashira reaction conditions and the expected β-sulfonium carbanions were obtained in a one

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• linked with a central pyrimidine core and another one is linked by a rigid thiophene cycle as a π-conjugated bridge. We have applied a usual synthetic protocol which includes eight successive steps: O-alkylation of 4-methoxyphenol (1), N-alkylation of carbazole (2), formylation or acetylation of a

• resulted N-alkyl carbazole (3), two-staged incorporation of thiophene moiety into obtained methyl ketone (4,5), condensation of the prepared aldehyde and methylketone (6), cyclization of thus prepared chalcone into 4,6-disubstituted 2-aminopyrimidine (7) and preparation of a target product – 4.6

• -carbazoles 3a,b were obtained via acetylation of the same carbazoles 1a,b [20]. The presence of an acetyl group in the resulted compounds 3a and 3b gives the opportunity to extend their conjugation chain via incorporation of an thiophene moiety with the help of a Vilsmeier–Haack–Arnold reaction. The reaction

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

• significant role in increasing the efficiency for OPVs [30][31]. However, fused π-bridges (such as thienothiophene) having a larger molecular structure and higher degree of conjugation are less explored with respect to thiophene and furan spacers. Thienothiophene ensures a highly delocalized electron system

• and higher charge carrier mobility due to its rigid and coplanar fused structure. Also, some thienothiophene-based polymers show a noticeable bathochromic shift in their absorption spectra in comparison with thiophene-substituted polymers [32][33][34]. Herein, keeping all these criteria in mind, we

• and donor, respectively [35][36]. The acceptor motif was further coupled with thiophene to increase the conjugation length and absorption. The same acceptor moiety was substituted with fluorine and the effect of this substitution on the polymeric and photovoltaic properties was studied. Furthermore

Isoxazole derivatives as new nitric oxide elicitors in plants

• Anca Oancea,
• Emilian Georgescu,
• Florentina Georgescu,
• Alina Nicolescu,
• Elena Iulia Oprita,
• Catalina Tudora,
• Lucian Vladulescu,
• Marius-Constantin Vladulescu,
• Florin Oancea and
• Calin Deleanu

Beilstein J. Org. Chem. 2017, 13, 659–664, doi:10.3762/bjoc.13.65

• procedures towards isoxazole derivatives were developed [36][37]. As part of our continued efforts to develop simple synthetic routes towards bioactive heterocyclic compounds [38][39][40][41][42][43], we report here the synthesis of several 3,5-isoxazole derivatives, bearing benzo[1,3]dioxole and thiophene

• ]. The thiophene is a core system of a large number of bioactive molecules such as antineoplastic agents [49], non-steroidal anti-inflammatory drugs [50] or compounds with antibacterial activities against several Gram-positive strains [51]. Thus, 3,5-disubstituted isoxazole derivatives were obtained by

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles

• Anastasia S. Kostyuchenko,
• Tatyana Yu. Zheleznova,
• Anton J. Stasyuk,
• Aleksandra Kurowska,
• Wojciech Domagala,
• Adam Pron and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2017, 13, 313–322, doi:10.3762/bjoc.13.34

• ) The ethyl esters of 2,2'-bithiophenes 7 having no (7a), an alkyl (7b), or a thienyl (7c) substituent in the C-5' position can be easily obtained by this method. On the other hand, the substitution of the thiophene ring with phenyl or fused aromatic rings is much more challenging and requires the

• between 389 and 409 nm, ascribed to the π–π* transition. A comparison of the absorption spectra of 15b and 15c–g indicates that the presence of a thiophene ring or carboaromatic substituents at the C-5' position in the 2,5-bis(2,2'-bithiophen-5-yl)-1,3,4-oxadiazole leads to a slight bathochromic shift of

• to the π–π* transition for the studied thiophene, phenyl, naphthalene and anthracene-substituted derivatives, shows a small hypsochromic shift with increasing spatial volume of the substituent R. This observation is in a full accordance with the aforementioned relationship of the molecule planarity

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• less reactive nitriles, the C–CN bond cleavage usually requires hydrogen under pressure and high temperatures [86]. Tao et al. reported the decyanation of 2-cyanobenzo[b]thiophene using hydrogen and Pd, Pt/TiO2 or Pd/TiO2-Cu as catalyst at 200–300 °C with yields varying from 79 to 90% (Scheme 14) [87

• both methods (34h) but, with the bromo counterpart, dehalogenation also occurs. 2-Cyanothiophene results in quantitative yield of thiophene 60 with both methods but cyanopyridines are not converted, probably due to the coordination abilities of the pyridine. Finally, decanenitrile is decyanated with

• reduction by NaH [81]. Reductive decyanation catalyzed by nickel nanoparticles. Yields are given in weight % from GC–MS data [85]. Decyanation of 2-cyanobenzo[b]thiophene [87]. Simplified pathways involved in transition-metal-promoted reductive decyanations [93][95]. Fe-catalyzed reductive decyanation