Indolizines and pyrrolo[1,2-c]pyrimidines decorated with a pyrimidine and a pyridine unit respectively

• Marcel Mirel Popa,
• Emilian Georgescu,
• Mino R. Caira,
• Florentina Georgescu,
• Constantin Draghici,
• Raluca Stan,
• Calin Deleanu and
• Florea Dumitrascu

Beilstein J. Org. Chem. 2015, 11, 1079–1088, doi:10.3762/bjoc.11.121

• structures of two of the starting materials, 4-(2-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine, are also reported. Keywords: indolizine; nitrogen heterocycles; N-ylide; 4-pyridylpyrimidine; pyrrolo[1,2-c]pyrimidine; Introduction Two heteroarenes linked through a single bond [1] proved to be versatile

• structural motifs for a broad range of compounds with applications as advanced fluorescent materials [2][3], ligands [4][5], bioactive compounds [6], and for the design of dynamic chemical devices [7][8][9][10]. The most accessible route to hybrid heteroarenes is the direct coupling [1][11][12]. However, in

• some cases alternative routes could be useful to achieve structural variety [13]. An alternative route is to start from accessible simple heteroarenes linked by a single bond and to transform one of them or both into more complex structures [14][15]. Nitrogen-containing compounds from the class of

Palladium-catalyzed 2,5-diheteroarylation of 2,5-dibromothiophene derivatives

• Fatma Belkessam,
• Aidene Mohand,
• Jean-François Soulé,
• Abdelhamid Elias and
• Henri Doucet

Beilstein J. Org. Chem. 2014, 10, 2912–2919, doi:10.3762/bjoc.10.309

• –2 mol % palladium catalysts, the target 2,5-diheteroarylated thiophenes were obtained in moderate to good yields and with a wide variety of heteroarenes such as thiazoles, thiophenes, furans, pyrroles, pyrazoles or isoxazoles. Moreover, sequential heteroarylation reactions allow the access to 2,5

• -diheteroarylated thiophenes bearing two different heteroaryl units. Keywords: aryl halides; catalysis; C–H bond activation; direct arylation; heteroarenes; palladium; Introduction 2,2':5',2"-Terthiophene (or 2,5-di(2-thienyl)thiophene) (Figure 1) and many of its derivatives are important structures due to their

• than other Pd-catalyzed cross-coupling reactions as it avoids the preparation of an organometallic derivative and also as the major byproducts of the reaction are not metallic salts but a base associated to HX. The metal-catalyzed direct arylation of a wide variety of heteroarenes using aryl halides as

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

• ) acetate as additives proved essential for achieving high yields of the desired trifluoromethylated arenes. 2-Arylpyridines, but also other aryl-substituted heteroarenes were successfully trifluoromethylated with complete regioselectivity in the position ortho to the aryl–heteroaryl bond, with moderate to

• and F.-L. Qing, where catalytic copper was used in the trifluoromethylation of sp2-C–H bonds by a nucleophilic CF3-releasing reagent [91]. In this paper, heteroarenes or arenes bearing acidic sp2-C–H bonds were trifluoromethylated by the Ruppert–Prakash reagent in presence of catalytic copper(II), a

• -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

AgOTf-catalyzed one-pot reactions of 2-alkynylbenzaldoximes with α,β-unsaturated carbonyl compounds

• Qiuping Ding,
• Dan Wang,
• Puying Luo,
• Meiling Liu,
• Shouzhi Pu and
• Liyun Zhou

Beilstein J. Org. Chem. 2013, 9, 1949–1956, doi:10.3762/bjoc.9.231

• processes. Isoquinoline derivatives, an important class of nitrogen-containing polycyclic heteroarenes, have attracted considerable attention because of their pharmacological activities, including antitumor, antifungal, antimalarial, antihypertensive and antihistaminic activity, and their photo- and

Gold-catalyzed intermolecular coupling of sulfonylacetylene with allyl ethers: [3,3]- and [1,3]-rearrangements

• Jungho Jun,
• Hyu-Suk Yeom,
• Jun-Hyun An and
• Seunghoon Shin

Beilstein J. Org. Chem. 2013, 9, 1724–1729, doi:10.3762/bjoc.9.198

• the scarcity of such examples [2][3][4][5]. Earlier examples in this vein include intermolecular reactions of electron-rich arenes and heteroarenes [2][3]. More recently, relatively polarized 1,1-disubstituted olefins were also found to react intermolecularly with phenylacetylenes or propiolic acids

Computational study of the rate constants and free energies of intramolecular radical addition to substituted anilines

• Andreas Gansäuer,
• Meriam Seddiqzai,
• Tobias Dahmen,
• Rebecca Sure and
• Stefan Grimme

Beilstein J. Org. Chem. 2013, 9, 1620–1629, doi:10.3762/bjoc.9.185

• to benzene with a rate constant of 3.8 × 102 M−1 s−1 at 79 °C. In this study it was also demonstrated that the rate constants for addition reactions to electron deficient (protonated) heteroarenes can be much higher due to polar effects. Despite these insightful investigations a more general picture

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

• research initiated spiralling interest by synthetic chemists in iminyl radical-mediated preparations. Recently iminyls have been generated from quite a variety of precursors [10][11][12][13][14][15], and their cyclisations onto arenes [16][17][18][19][20][21] and heteroarenes [22][23][24] have attracted

• derivatives of oximes with various aromatic and heteroaromatic architectures (Figure 1). Compounds 1a–f contain comparatively rigid arms and their aromatic acceptors range from electron-withdrawing to electron-releasing in character. In compounds 2a,b and 3 heteroarenes replace the benzene rings and in 4 the

Direct alkenylation of indolin-2-ones by 6-aryl-4-methylthio-2H-pyran-2-one-3-carbonitriles: a novel approach

• Sandeep Kumar,
• Ramendra Pratap,
• Abhinav Kumar,
• Brijesh Kumar,
• Vishnu K. Tandon and
• Vishnu Ji Ram

Beilstein J. Org. Chem. 2013, 9, 809–817, doi:10.3762/bjoc.9.92

• ; 2H-pyran-2-one; Introduction 6-Aryl-4-methylthio-2H-pyran-2-one-3-carbonitriles have emerged as versatile synthons for the construction of an array of arenes and heteroarenes through base-induced ring transformation by nitrogen, sulfur and carbon nucleophiles [1]. However, suitably functionalized 2H

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

• with heteroarenes. Keywords: aryl chlorides; atom-economy; C–H bond activation; C–H functionalization; carbenes; palladium; pyrroles; Introduction N-Heterocyclic carbenes (NHC) have emerged as an important class of ligands in the development of homogeneous catalysis [1][2][3][4][5][6][7][8][9]. Such

• the palladium-catalyzed coupling of heteroarenes with aryl halides through a C–H bond activation has been largely explored. On the other hand, the influence of carbene ligands for such couplings remains largely unexplored [40][41][42][43][44][45][46][47]. Quite congested N-heterocyclic carbene

Copper-catalyzed CuAAC/intramolecular C–H arylation sequence: Synthesis of annulated 1,2,3-triazoles

• Rajkumar Jeyachandran,
• Harish Kumar Potukuchi and
• Lutz Ackermann

Beilstein J. Org. Chem. 2012, 8, 1771–1777, doi:10.3762/bjoc.8.202

• ; heteroarenes; triazoles; Introduction Transition-metal-catalyzed C–H bond functionalizations are increasingly viable tools for step-economical syntheses of various valuable bioactive compounds [1][2][3], which avoid the preparation and use of preactivated substrates [4][5][6][7][8][9][10][11][12][13][14][15

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

• rearrangement that is operative during the alkylation of indoles [46]. In 1969, Fujiwara and Moritani reported the alkenylation of arenes catalyzed by Pd(OAc)2, using Cu(OAc)2 or AgOAc as oxidants [47]. This strategy provides a convenient method for the synthesis of olefins linked to heteroarenes, including

Palladium-catalyzed substitution of (coumarinyl)methyl acetates with C-, N-, and S-nucleophiles

• Kalicharan Chattopadhyay,
• Erik Fenster,
• Alexander J. Grenning and
• Jon A. Tunge

Beilstein J. Org. Chem. 2012, 8, 1200–1207, doi:10.3762/bjoc.8.133

• halomethylcoumarin and highly stabilized nucleophiles or amines [6][7][8][9][10][11][12][13][14][15]. Due to the sensitivity and toxicity of related benzyl halides, there has been interest in catalytically activating hydroxymethylarene and heteroarenes (e.g., benzyl alcohol derivatives) toward reactions with

Parallel solid-phase synthesis of diaryltriazoles

• Matthias Wrobel,
• Jeffrey Aubé and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 1027–1036, doi:10.3762/bjoc.8.115

• phenyl ring of the benzoic acid as constant structural elements and the third ring consisting either of substituted benzenes, heteroarenes or a polycyclic aromatic compound. Lower product yields were obtained in this series of compounds, ranging from 21 to 63%. The lower reactivity of the aromatic azide

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

• ) catalysis with arylbromides (Scheme 30) [80][81]. Transition metal-catalyzed dehydrogenative cross-coupling Last year, Hu and You reported the first extended study of Pd(II)- and Cu(II)- catalyzed oxidative C–H/C–H cross-coupling of electron-rich heteroarenes, including benzoxazole coupled with 2

Meta-metallation of N,N-dimethylaniline: Contrasting direct sodium-mediated zincation with indirect sodiation-dialkylzinc co-complexation

• David R. Armstrong,
• Liam Balloch,
• Eva Hevia,
• Alan R. Kennedy,
• Robert E. Mulvey,
• Charles T. O'Hara and
• Stuart D. Robertson

Beilstein J. Org. Chem. 2011, 7, 1234–1248, doi:10.3762/bjoc.7.144

• direct zincation of functionalised arenes and heteroarenes [9][10]. However, common limitations have been noted for the use of this reagent with some electron poor and heterocyclic compounds which suffer from the drawback of limited regioselectivity, whilst several activated aromatic compounds bearing

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

• efficient Friedel–Crafts alkylations of arenes and heteroarenes using only catalytic amounts of a Lewis acid has gained much attention over the last decade. The new catalytic approaches described in this review are favoured over classical Friedel–Crafts conditions as benzyl-, propargyl- and allyl alcohols

• descriptions of a Lewis acid used in organic synthesis but also the first example of what was later to be called Friedel–Crafts alkylation (FC alkylation) after its inventors. Today Friedel–Crafts alkylations remain the method of choice for the alkylation of arenes and heteroarenes. Over the intervening years

• 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

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

• [1,2-b:4,3-b′]dithiophene; McMurry reaction; preparation; Introduction With considerable environmental stability and flexibility in synthesis, π-extended heteroarenes containing thiophene rings within an polyaromatic ring system are currently of great interest because they can potentially be used to

• 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

Synthesis of rigidified flavin–guanidinium ion conjugates and investigation of their photocatalytic properties

• Harald Schmaderer,
• Mouchumi Bhuyan and
• Burkhard König

Beilstein J. Org. Chem. 2009, 5, No. 26, doi:10.3762/bjoc.5.26

• flavin heteroarenes are observed. The structure of compound 1 in the solid state (Figure 2) shows an almost identical orientation of the flavin group to that of the acid 6. The acyl guanidinium ion group is almost planar and in a parallel orientation relative to the Kemp’s acid imide group. 2-D NMR

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

• Lewis acid/transition metal free synthesis of acyl benzothiophenes could provide an easy access to a library of benzothiophene based analogues of potential biological interest. Notably, while the use of various arenes/heteroarenes has been explored in the previous study, [25][26][27][28][29][30] the use

m-Iodosylbenzoic acid – a convenient recyclable reagent for highly efficient aromatic iodinations

• Andreas Kirschning,
• Mekhman S. Yusubov,
• Roza Y. Yusubova,
• Ki-Whan Chi and
• Joo Y. Park

Beilstein J. Org. Chem. 2007, 3, No. 19, doi:10.1186/1860-5397-3-19

• Table 2). Addition of aqueous H2SO4 accelerated the iodination of benzenes. For heteroarenes 7j and 7o this additive was not required and if an additional alcohol group was present (see 7n), addition of aqueous H2SO4 resulted in its oxidation. Compared to diacetoxyiodobenzene (DIB) 1a and its polymeric