Hindered aryl bromides for regioselective palladium-catalysed direct arylation at less favourable C5-carbon of 3-substituted thiophenes

• Rongwei Jin,
• Charles Beromeo Bheeter and
• Henri Doucet

Beilstein J. Org. Chem. 2014, 10, 1239–1245, doi:10.3762/bjoc.10.123

• use of the congested aryl bromide 2-bromo-1,3-dichlorobenzene as coupling partner allows to modify the regioselectivity of the arylation of 3-substituted thiophene derivatives in favour of carbon C5. The coupling of this aryl bromide with a variety of 3-substituted thiophenes gave in all cases the

• different aryl units. Keywords: aryl bromides; atom economy; C–H bond activation; palladium; regioselectivity; thiophenes; Introduction As thiophenes bearing aryl substituents are known to be present in several bioactive molecules and are used as precursors of materials, the regioselective introduction of

• aryls on thiophenes is an important research area in organic synthesis. The coupling of thiophene derivatives with aryl halides via a C–H bond activation/functionalisation [1][2][3][4][5][6][7][8][9][10][11][12] provides an environmentally attractive and cost-effective procedure for the preparation of a

The Ugi four-component reaction as a concise modular synthetic tool for photo-induced electron transfer donor-anthraquinone dyads

• Sarah Bay,
• Gamall Makhloufi,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 1006–1016, doi:10.3762/bjoc.10.100

• ]. This photo-induced electron transfer (PET) [30][31][32][33][34] has been investigated with donors such as porphyrines, polycyclic aromatic hydrocarbons, perylenediimides and (oligo)thiophenes [35][36], tetrathiafulvalenes [37], as well as phenothiazine and its derivatives [22][38][39][40]. The latter

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• -subsituted alkenes were sometimes obtained along with the desired addition products (Scheme 9). Afterwards, N. Kamigata et al. applied this system to arenes [99] and heteroarenes (furans, pyrroles and thiophenes) [102][103][104] and gave a full account of this work (Scheme 9) [101]. Monosubstituted benzenes

• gave mixtures of the ortho-, meta- and para-isomers. The reaction was much more regioselective in the case of thiophenes, where 2-perfluoroalkylated products were obtained, as long as at least one of the positions α to sulfur was unsubstituted; otherwise β-functionalization occurred. The same comment

• [114] as well as of various arenes and heteroarenes (pyridines, pyrimidines, pyrazines, quinolines, pyrroles, thiophenes, furans, pyrazoles, imidazoles, thiazoles, oxazoles, thiadiazoles, triazoles) [115]. The yields were low to excellent, depending on the substrate (Scheme 12 and Figure 20). Iron(II

Zinc–gold cooperative catalysis for the direct alkynylation of benzofurans

• Yifan Li and
• Jérôme Waser

Beilstein J. Org. Chem. 2013, 9, 1763–1767, doi:10.3762/bjoc.9.204

• knowledge, the direct alkynylation of benzofurans is still an unknown process. Since 2009, our group has developed a mild gold-catalyzed [14][15][16][17] method for the alkynylation of electron-rich aryls such as indoles and pyrroles [18], thiophenes [19], anilines [20] and furans [21]. Key for success was

Incorporation of perfluorohexyl-functionalised thiophenes into oligofluorene-truxenes: synthesis and physical properties

• Neil Thomson,
• Alexander L. Kanibolotsky,
• Joseph Cameron,
• Tell Tuttle,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2013, 9, 1243–1251, doi:10.3762/bjoc.9.141

• , such as an ethylene chain, which can lessen the inductive effect [12]. Due to the widespread industrial use of polythiophenes, such as P3HT, analogous poly(perfluoroalkyl)thiophenes have received some interest due to their ability to affect certain properties of the polymer, such as the

Enhancement of efficiency in organic photovoltaic devices containing self-complementary hydrogen-bonding domains

• Rohan J. Kumar,
• Jegadesan Subbiah and
• Andrew B. Holmes

Beilstein J. Org. Chem. 2013, 9, 1102–1110, doi:10.3762/bjoc.9.122

• maintained by introduction of alkyl substituents at the β-position of the thiophenes, and the NH-cyanopyridone unit could be unmasked for hydrogen-bonding. In turn, this may allow access to higher order supramolecular structures, promoting charge transport and increasing the fill factor and efficiency of

Ring-opening reaction of 2,5-dioctyldithieno[2,3-b:3',2'-d]thiophene in the presence of aryllithium reagents

• Hao Zhong,
• Jianwu Shi,
• Jianxun Kang,
• Shaomin Wang,
• Xinming Liu and
• Hua Wang

Beilstein J. Org. Chem. 2013, 9, 767–774, doi:10.3762/bjoc.9.87

• the synthesis of a series of symmetric substituted dithieno[2,3-b:3',2'-d]thiophenes and their ring-opening reactions in the presence of n-BuLi. The 3,3'-bithiophene-2-carbaldehydes were generated after quenching with an electrophile, i.e., dry DMF (Scheme 1) [5]. The uncommon ring opening of fused

• -b]thiophene [13]. More recently, Nenajdenko et al. reported that fused thieno[2,3-b]thiophenes and some [3,2-b]-fused oligothiophenes were attacked by organo-lithium reagents resulting in the cleavage of thiophene rings [14]. They found when competitive deprotonation of the substrate was possible

• , high selectivity towards the ring opening was observed with n-BuLi when compared with other organolithium reagents. However, most of these ring-opening reactions mentioned above take place by using n-BuLi as the nucleophile to attack the sulfur atoms of thiophenes. Other organolithium reagents have

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• intramolecular alkenylation on a range of other electron-rich heterocycles, including pyrroles, furans and thiophenes [63][64]. The intramolecular Pd(II)-catalyzed reaction of the 3-alkenylindoles 14 gave rise to the carbocyclic 5-membered ring-fused products 15 (Scheme 12) [65][66]. This procedure involves O2

Thiophene-based donor–acceptor co-oligomers by copper-catalyzed 1,3-dipolar cycloaddition

• Stefanie Potratz,
• Amaresh Mishra and
• Peter Bäuerle

Beilstein J. Org. Chem. 2012, 8, 683–692, doi:10.3762/bjoc.8.76

• –donor type, in which thiophene moieties work as donor and 1,2,3-triazoles as acceptor units. In this respect, terminally ethynylated (oligo)thiophenes were coupled to halogenated (oligo)thiophenes in the presence of sodium azide and a copper catalyst. Optoelectronic properties of various thiophene-1,2,3

• electronic communication between the chromophores [21][22][23][31]. It has also been shown that a 1,2,3-triazole can act as a strong σ-electron donor [26] or as a weak π-electron acceptor [15]. In this study, we aimed at the combination of electron-rich (oligo)thiophenes as donors and electron-deficient

• - versus 2-azidothiophenes, 3-halogenated thiophenes give higher yields than 2-halogenated thiophenes, 2-substituted benzenes higher yields than thiophenes, and thiophenes higher yields than bithiophenes. As expected, 3-halogenothiophenes gave higher yields than 2-halogenothiophenes (e.g., 8 and 9

Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

• Jiří Kulhánek and
• Filip Bureš

Beilstein J. Org. Chem. 2012, 8, 25–49, doi:10.3762/bjoc.8.4

• connecting both acceptor and donor moieties play a crucial role. It was shown that polarizable subunits, such as olefins and thiophenes, increase the chromophore (hyper)polarizability significantly. Thus, the most important structural factors affecting D–A interaction responsible for the linear and nonlinear

Pseudo five-component synthesis of 2,5-di(hetero)arylthiophenes via a one-pot Sonogashira–Glaser cyclization sequence

• Dominik Urselmann,
• Dragutin Antovic and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2011, 7, 1499–1503, doi:10.3762/bjoc.7.174

• ; thiophenes; Introduction Over the past decades 2,5-di(hetero)aryl substituted thiophenes [1][2] have constantly attracted a lot of interest, especially as charge-transport materials in electronic [3] and optoelectronic [4][5][6] devices, but also in drug design as antitumor [7] or anti-inflammatory agents

• [8] or in plaque imaging [9]. Most commonly the methodological access to these targets has been based upon Pd- or Ni-catalyzed coupling of dihalo thiophenes with organometallic (hetero)aryl derivatives by virtue of Suzuki [10] or Stille [11] coupling. Even though this strategy for the synthesis of

• symmetrical 2,5-diarylated thiophenes has proven to be efficient and general, all of these synthetic routes share the drawback of ultimately requiring two different halogenated (hetero)arenes and the separate conversion into an organometallic derivative in an additional step. From a practical point of view

Combined directed ortho-zincation and palladium-catalyzed strategies: Synthesis of 4,n-dimethoxy-substituted benzo[b]furans

• Verónica Guilarte,
• M. Pilar Castroviejo,
• Estela Álvarez and
• Roberto Sanz

Beilstein J. Org. Chem. 2011, 7, 1255–1260, doi:10.3762/bjoc.7.146

• 2,3-difunctionalized phenol derivatives were applied to the synthesis of 4-functionalized benzo[b]furans [39], 4- or 7-alkoxyindoles [40], and 7-oxy-substituted benzo[b]thiophenes [41] by employing Pd-catalyzed cross-coupling reactions or halocyclization processes. Following our interest in the

One-pot four-component synthesis of pyrimidyl and pyrazolyl substituted azulenes by glyoxylation–decarbonylative alkynylation–cyclocondensation sequences

• Charlotte F. Gers,
• Julia Rosellen,
• Eugen Merkul and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2011, 7, 1173–1181, doi:10.3762/bjoc.7.136

• by our smooth glyoxylation–alkynylation sequences with a variety of unfunctionalized π-nucleophiles, such as pyrazoles, thiophenes, furans, and even the hydrocarbon azulene (1a) [53], we decided to perform optimization studies of the glyoxylation–decarbonylative alkynylation with guaiazulene (1b), a

Photocycloaddition of aromatic and aliphatic aldehydes to isoxazoles: Cycloaddition reactivity and stability studies

• Axel G. Griesbeck,
• Marco Franke,
• Jörg Neudörfl and
• Hidehiro Kotaka

Beilstein J. Org. Chem. 2011, 7, 127–134, doi:10.3762/bjoc.7.18

• reagent on the liberated benzaldehyde. Conclusion The photocycloaddition of electronically excited carbonyl compounds to isoxazoles is clearly less effective than with other five-membered aromatic or non-aromatic heterocycles (furans, thiophenes, pyrroles, oxazoles, dihydrofurans, dihydropyrroles) [1

Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

• Carolin Fischer and
• Burkhard Koenig

Beilstein J. Org. Chem. 2011, 7, 59–74, doi:10.3762/bjoc.7.10

• [53]. Intramolecular palladium-catalysed N-arylations have been applied to substituted arenes and thiophenes with good to excellent yields. Electron-rich bromides gave the best results, while pyridine derivatives were unreactive [54]. Another intramolecular approach enabled the stereoselective

Syntheses and properties of thienyl-substituted dithienophenazines

• Annemarie Meyer,
• Eva Sigmund,
• Friedhelm Luppertz,
• Gregor Schnakenburg,
• Immanuel Gadaczek,
• Thomas Bredow,
• Stefan-S. Jester and
• Sigurd Höger

Beilstein J. Org. Chem. 2010, 6, 1180–1187, doi:10.3762/bjoc.6.135

• well as cyclic and polycyclic thiophenes are valuable templates for the epitaxial coadsorption of adlayers, in particular for fullerenes and metallacycles [14][15][16][17]. Results and Discussion Here we report the syntheses of two isomeric benzodithiophenediones, their respective phenazines and their

• larger delocalized π-system, which lowers the HOMO-LUMO gap as discussed above. The difference density of 12a (Figure 2c) shows that the S0-S1 excitation leads to an intramolecular charge transfer (CT) from the thiophenes to the phenazine part of the molecule. These calculations verify our initial

Redox-active tetrathiafulvalene and dithiolene compounds derived from allylic 1,4-diol rearrangement products of disubstituted 1,3-dithiole derivatives

• Filipe Vilela,
• Peter J. Skabara,
• Christopher R. Mason,
• Thomas D. J. Westgate,
• Asun Luquin,
• Simon J. Coles and
• Michael B. Hursthouse

Beilstein J. Org. Chem. 2010, 6, 1002–1014, doi:10.3762/bjoc.6.113

• solution. X-ray crystallographic data confirmed that the isolated nickel dithiolene was monoanionic and that only one of the two possible isomers of this product was isolated by the recrystallisation method (both non-fused thiophenes are on the same side of the fused framework). The molecular structure of

• the compound is shown in Figure 4 and the packing diagram is shown in Figure 5. The peripheral, non-fused thiophenes are significantly distorted from the plane of the fused skeleton, leaving them weakly conjugated to the main π-framework. The torsion angles for C22–C21–C15–C14 and C10–C9–C5–C6 are

• thiophenes may be sterically demanding, but the formation of short oligomers cannot be ruled out in this mechanism. Conclusion We have shown that the unusual 1,4-aryl shift observed in the presence of perchloric acid for electron-rich 1,3-dithiole-2-thione and TTF derivatives can be exploited to further

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• -isomers [87]. Unlike pyrroles, furan, thiophene and selenophene react with CF3SCl only in the presence of catalysts. For selenophene [84] and thiophenes [85] SnCl4 is sufficient, whilst furans require more forcing conditions usually involving prolonged heating (20 h at 60 °C) and in pyridine for

• -groups into heterocyclic compounds (except for pyrrole and its derivatives) occurs in the presence of perfluoroalkanesulfonic acids (Scheme 20). Incorporation of the second fluoroalkylsulfanyl group into thiophenes [85] and selenophene [84] is possible in the presence of CF3SO3H. However, reaction of

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• bearing methyl, methoxy or hydroxy functionalities as well as heteroarenes, including thiophenes or 3-methylindole with a good para/ortho/meta regioselectivity (Scheme 10). In addition, they successfully used benzyl acetates, 1-phenylethanol and β-hydroxy-substituted benzyl alcohols as alkylating reagents

• indoles, thiophenes, pyrroles or furans gave the desired anti-1,1,2-triarylalkanes 110 in good yields and with high diastereoselectivities (Scheme 40B). BF3•OEt2 and TFA were used in stoichiometric amounts to promote this reaction. However, application of BF3 resulted in significantly higher reactivity

Gold film- catalysed benzannulation by Microwave- Assisted, Continuous Flow Organic Synthesis (MACOS)

• Gjergji Shore,
• Michael Tsimerman and
• Michael G. Organ

Beilstein J. Org. Chem. 2009, 5, No. 35, doi:10.3762/bjoc.5.35

• ., entries a, b, c) and was also useful for the preparation of heterocycle-containing molecules such as pyridines and thiophenes (e.g., entries e–j). A survey of different functional groups revealed a broad tolerance including silyl groups (entries b and h), halides (entries g and i), ethers, (entry c

Synthesis of thienyl analogues of PCBM and investigation of morphology of mixtures in P3HT

• Fukashi Matsumoto,
• Kazuyuki Moriwaki,
• Yuko Takao and
• Toshinobu Ohno

Beilstein J. Org. Chem. 2008, 4, No. 33, doi:10.3762/bjoc.4.33

• procedure [22], as shown in Scheme 1. First, benzo[b]thiophene and thieno[3,2-b]thiophenes were acylated by using SnCl4; the acylation was performed at low temperature as a safeguard against the high reactivity of the thienyl groups (yields: 1a; 15%, 1b; 46%, 1c; 74%, 1d; 33%). Glutaric acid monomethyl

Development of potential manufacturing routes for substituted thiophenes – Preparation of halogenated 2-thiophenecarboxylic acid derivatives as building blocks for a new family of 2,6-dihaloaryl 1,2,4-triazole insecticides

• John W. Hull Jr.,
• Duane R. Romer,
• David E. Podhorez,
• Mezzie L. Ash and
• Christine H. Brady

Beilstein J. Org. Chem. 2007, 3, No. 23, doi:10.1186/1860-5397-3-23

• -Trichloro-2-thiophenecarbonitrile, 3 Our investigation of synthetic routes to the 1,2,4-triazole insecticide XR-906 required a supply of the chlorinated thiophenes 2 or 3 as building blocks for attachment of the C-ring portion. Preparation of trichloro-2-thiophenecarbonitrile 3 has been reported starting

• . However, also present were the butylated thiophenes 25 and 26 (Scheme 5), identified by GC/MS. Thus, in THF the n-butyllithium reagent was too reactive, leading to butyl addition products rather than clean metallation to the 2-thienyllithium intermediate. After successful metallation of 22 and treatment

• 1–3 from commercially available raw materials have been developed and demonstrated on a laboratory scale. The halogenated thiophenes with an acid chloride or nitrile functional group at the 2-position are key building blocks for a new family of 1,2,4-triazole insecticides. A one-pot bromination