Synthesis of functionalized spiro[indoline-3,4’-pyridines] and spiro[indoline-3,4’-pyridinones] via one-pot four-component reactions

• Li-Juan Zhang,
• Qun Wu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 846–851, doi:10.3762/bjoc.9.97

• malononitrile afforded the functionalized spiro[indoline-3,4’-pyridine] derivatives in good yields. Similar reactions with ethyl cyanoacetate successfully afforded the functionalized spiro[indoline-3,4’-pyridines] and spiro[indoline-3,4’-pyridinones] as the main products according to the structures of the

• [12][13][14][15][16][17][18][19][20][21][22][23]. Recently, Perumal and we have both developed an efficient synthetic procedure for functionalized spiro[indoline-3,4’-pyridines] by domino reactions of in situ generated β-enamino esters, isatin and malononitrile with triethylamine as the base catalyst

• reactions of arylamines, methyl propiolate, aromatic aldehydes and malononitrile (ethyl cyanoacetate) and successfully developed a facile synthetic procedure for functionalized spiro[indoline-3,4’-pyridines] and spiro[indoline-3,4’-pyridinones]. Results and Discussion The efficient formation of

High-spin intermediates of the photolysis of 2,4,6-triazido-3-chloro-5-fluoropyridine

• Sergei V. Chapyshev,
• Denis V. Korchagin,
• Patrik Neuhaus and
• Wolfram Sander

Beilstein J. Org. Chem. 2013, 9, 733–742, doi:10.3762/bjoc.9.83

• ), quintet 2-azido-3-chloro-5-fluoropyridyl-4,6-dinitrene (DQ = 0.209 cm−1, EQ = 0.039 cm−1) and septet 3-chloro-5-fluoropyridyl-2,4,6-trinitrene (DS = −0.1021 cm−1, ES = −0.0034 cm−1). Preferential photodissociation of the azido groups located in ortho-positions to the fluorine atom of pyridines is

• fluorine atom of pyridines. On comparison with the chlorine, the fluorine is a much more electron-negative and less bulky atom. Both of these factors favor strong π– conjugation of the ortho-azido groups with the pyridine ring. On photoexcitation, such azido groups should be more efficiently involved in

• -positions to the fluorine atom of pyridines is associated with strong π-conjugation of these groups with the pyridine ring. On photoexcitation, such azido groups are more efficiently involved in reorganization of the molecular electronic system and more easily adopt geometries of the locally excited

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• (nitrile, ketones, esters, pyridines, tetrazoles, etc.) are particularly suitable. Benzyl radicals are not reactive enough towards unactivated alkenes; they tend to accumulate in the medium and ultimately dimerise. (b) The addition product, 30, being itself a xanthate, allows the implementation of a second

Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

Dipyrazolo[1,5-a:4',3'-c]pyridines – a new heterocyclic system accessed via multicomponent reaction

• Wolfgang Holzer,
• Gytė Vilkauskaitė,
• Eglė Arbačiauskienė and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2012, 8, 2223–2229, doi:10.3762/bjoc.8.251

• , 50254 Kaunas, Lithuania 10.3762/bjoc.8.251 Abstract The synthesis of dipyrazolo[1,5-a:4',3'-c]pyridines is described. Easily obtainable 5-alkynylpyrazole-4-carbaldehydes, p-toluenesulfonyl hydrazide, and an aldehyde or ketone containing an α-hydrogen atom were reacted in a silver triflate catalyzed

• [21], 1,5-dihydro- resp. 2,5-dihydro-4H-pyrazolo[4,3-c]pyridin-4-ones [20], and pyrazolo[4,3-c]pyridines [22]. In continuation of these studies we herein present the synthesis and detailed NMR spectroscopic characterization of the new heterocyclic system dipyrazolo[1,5-a:4',3'-c]pyridine. The access

• synthesis of H-pyrazolo[5,1-a]isoquinolines by a one-pot tandem reaction of 2-alkynylbenzaldehydes, sulfonohydrazide, and ketones or aldehydes [27]. In our case, application of pyrazolecarbaldehydes 1 should enable access to the desired dipyrazolo[1,5-a:4',3'-c]pyridines 5. In order to test the reaction

Intramolecular carbolithiation of N-allyl-ynamides: an efficient entry to 1,4-dihydropyridines and pyridines – application to a formal synthesis of sarizotan

• Wafa Gati,
• Mohamed M. Rammah,
• Mohamed B. Rammah and
• Gwilherm Evano

Beilstein J. Org. Chem. 2012, 8, 2214–2222, doi:10.3762/bjoc.8.250

• 10.3762/bjoc.8.250 Abstract We have developed a general synthesis of polysubstituted 1,4-dihydropyridines and pyridines based on a highly regioselective lithiation/6-endo-dig intramolecular carbolithiation from readily available N-allyl-ynamides. This reaction, which has been successfully applied to the

• formal synthesis of the anti-dyskinesia agent sarizotan, further extends the use of ynamides in organic synthesis and further demonstrates the synthetic efficiency of carbometallation reactions. Keywords: carbolithiation; carbometallation; dihydropyridines; organolithium reagents; pyridines; sarizotan

• carbolithiation of ynamides, which may provide an interesting entry to highly functionalized 1,4-dihydropyridines [27][28][29] and pyridines [30][31][32][33], most useful building blocks in organic synthesis and medicinal chemistry as well. Our strategy is summarized in Scheme 1 and is based on the following

Cation affinity numbers of Lewis bases

• Christoph Lindner,
• Raman Tandon,
• Boris Maryasin,
• Evgeny Larionov and
• Hendrik Zipse

Beilstein J. Org. Chem. 2012, 8, 1406–1442, doi:10.3762/bjoc.8.163

• experimentally measured nucleophilicity parameters N of these systems (Figure 8) [23][24]. While correlation within each of the catalyst families is very good, it is also apparent that the pyridines and phosphanes form clearly separate correlation lines. This is commonly understood as a reflection of

• -dialkyl-4-aminopyridines (54, 369, 370, 373–377) it is interesting to see how elongation of the alkyl substituents leads to a rapid convergence of the ACA values. The two methyl groups in 54 lead to an ACA value just 7 kJ/mol or 3% below the two octyl groups (377). The group of pyridines derived from the

• 378 and 57. This is in remarkable contrast to DMAP derivatives such as 364 carrying non-annelated alkyl substituents in 3- and/or 5-position with clearly lower ACA values. Comparison of pyridines 63 and 388 furthermore shows that alkyl groups directly attached to the amine substituents in 3- and 5

Similarity analysis, synthesis, and bioassay of antibacterial cyclic peptidomimetics

• Workalemahu M. Berhanu,
• Mohamed A. Ibrahim,
• Girinath G. Pillai,
• Alexander A. Oliferenko,
• Levan Khelashvili,
• Farukh Jabeen,
• Bushra Mirza,
• Farzana Latif Ansari,
• Ihsan ul-Haq,
• Said A. El-Feky and
• Alan R. Katritzky

Beilstein J. Org. Chem. 2012, 8, 1146–1160, doi:10.3762/bjoc.8.128

• ]. Many reports describe the successful use of heterocycles as peptide-bond surrogates or as potential protein-recognition motifs to achieve superior potency in biological assays [10][11][12][13][14]. Pyridines are well-established as important heterocycles in medicinally and biologically active compounds

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

• (19). In 2001, Yamato reported an oxacalix[3]arene with pendant pyridines linked by amide bonds [34]. The intramolecular hydrogen bonds between neighbouring amide groups enforced a flattened-cone conformer for the macrocycle, which prevented binding to both metal cations and, to a large extent, alkyl

Access to pyrrolo-pyridines by gold-catalyzed hydroarylation of pyrroles tethered to terminal alkynes

• Elena Borsini,
• Gianluigi Broggini,
• Andrea Fasana,
• Chiara Baldassarri,
• Angelo M. Manzo and
• Alcide D. Perboni

Beilstein J. Org. Chem. 2011, 7, 1468–1474, doi:10.3762/bjoc.7.170

• pyrrolo[2,3-c]pyridines (Scheme 1) [33]. The reaction provided also the isomeric pyrrolo[3,2-c]pyridines arising from 1,2-migration of the amide moiety. Having recently broadened our studies toward gold catalysis [34][35], we have been intrigued by the investigation of a gold-catalyzed intramolecular

• gold-catalyzed procedure to achieve pyrrolo[2,3-c]pyridines and pyrrolo[3,2-c]pyridines represents a valuable alternative to the Pd-catalyzed cyclization of the analogue allylamides. Experimental General Melting points were determined by capillary method with a Büchi B-540 apparatus and are uncorrected

Functionalization of heterocyclic compounds using polyfunctional magnesium and zinc reagents

• Paul Knochel,
• Matthias A. Schade,
• Sebastian Bernhardt,
• Georg Manolikakes,
• Albrecht Metzger,
• Fabian M. Piller,
• Christoph J. Rohbogner and
• Marc Mosrin

Beilstein J. Org. Chem. 2011, 7, 1261–1277, doi:10.3762/bjoc.7.147

• addition of a catalytic amount of CuCN·2LiCl [7], the arylzinc intermediate is allylated with allyl bromide providing the ester 3 in 94% isolated yield (Scheme 2) [6]. This method can be extended to a broad variety of functionalized heterocyclic iodides such as the pyridines 4 and 7. The corresponding zinc

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• nitriles in the presence of cationic gold catalysts, such as Et3PAuCl/AgSbF6, to give tetrasubstituted pyridines 30 in good yields (Scheme 18) [72]. Cycloadditions initiated by gold-activation of propargyl esters These cycloadditions are a special case of those based on the activation of alkynes and

A practical two-step procedure for the preparation of enantiopure pyridines: Multicomponent reactions of alkoxyallenes, nitriles and carboxylic acids followed by a cyclocondensation reaction

• Christian Eidamshaus,
• Roopender Kumar,
• Mrinal K. Bera and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2011, 7, 962–975, doi:10.3762/bjoc.7.108

• substrate scope and leads to differentially substituted enantiopure pyridines in good to moderate yields. The preparation of diverse substituted lactic acid derived pyrid-4-yl nonaflates is described. Additional evidence for the postulated mechanism of the multicomponent reaction is presented. Keywords

• : allenes; enantiopure pyridines; ketoenamides; multicomponent reactions; nonaflates; Introduction The pyridine core is ubiquitous in pharmacologically active agents, agrochemicals and natural products [1][2][3][4][5]. The HMG-CoA reductase inhibitors Glenvastatin and Cerivastatin are exemplarily mentioned

• as pharmaceuticals that feature the pyridine nucleus [6][7][8][9][10]. Natural products that contain a pyridine ring include the 3-alkylpyridine alkaloid niphatesine C and the fuzanin family [11][12]. Moreover, the ability to form coordination compounds makes pyridines ideal ligands for transition

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• -ynes 282 and non-activated nitriles was introduced by Barluenga and co-workers [148]. The sequence is promoted by both, gold(I) and gold(III) catalysts and leads to the regioselective formation of tetrasubstituted pyridines 289. The initial coordination of the triple bond to the gold catalyst forms

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• -dielectrophiles has been extensively used for the preparation of bicyclic nitrogen heterocycles, especially in the preparation of condensed heterocycles such as pyrazolo[3,4-d]pyrimidines, pyrazolo[3,4-b]pyridines, imidazopyrazoles etc. In view of significant interest in the synthesis of these heterocyclics, we

The catalytic performance of Ru–NHC alkylidene complexes: PCy₃ versus pyridine as the dissociating ligand

• Stefan Krehl,
• Diana Geißler,
• Sylvia Hauke,
• Oliver Kunz,
• Lucia Staude and
• Bernd Schmidt

Beilstein J. Org. Chem. 2010, 6, 1188–1198, doi:10.3762/bjoc.6.136

• pyridines as placeholders. Originally, complex G was synthesized as a precursor for mixed NHC-phosphine complexes other than D [25][26][27][28] or, very recently, for the synthesis of Ru-alkylidenes with two different NHC ligands [29]. Comparatively little information is available concerning the catalytic

Design and synthesis of a cyclitol-derived scaffold with axial pyridyl appendages and its encapsulation of the silver(I) cation

• Pierre-Marc Léo,
• Christophe Morin and
• Christian Philouze

Beilstein J. Org. Chem. 2010, 6, 1022–1024, doi:10.3762/bjoc.6.115

• triclinic system, with a pseudo-ternary axis of symmetry. Its coordination sphere involves all 3 nitrogen atoms as well as the 3 oxygen atoms which are implied in the linkage of the pyridines (Figure 3). Bond distances and angles (see Supporting Information File 1) are in accord with those of known silver

Structure and reactivity in neutral organic electron donors derived from 4-dimethylaminopyridine

• Jean Garnier,
• Alan R. Kennedy,
• Leonard E. A. Berlouis,
• Andrew T. Turner and
• John A. Murphy

Beilstein J. Org. Chem. 2010, 6, No. 73, doi:10.3762/bjoc.6.73

• a polymethylene chain linking the two pyridine-derived rings and (ii) the nature of the nitrogen substituents on the 4 and 4′ positions of the precursor pyridines. Restricting the bridge length to two methylene units significantly altered the redox profile, while changes in the nitrogen-substituents

• of the electron pair on the 4-substituent into the pyridine ring. Accordingly, the disalts 21 and 22 were prepared from these 4-substituted pyridines [43][45] and converted into their hexafluorophosphates 21′ and 22′, and then examined by cyclic voltammetry. Each showed a reversible two-electron

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective

• Norio Shibata,
• Andrej Matsnev and
• Dominique Cahard

Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65

• products in high yields. Primary and secondary amines also reacted with 20b to afford N-CF3 products in good yields. Tertiary amines as well as pyridines gave quaternary ammonium and pyridinium salts, respectively. Electrophilic trifluoromethylation could also be achieved by thermal decomposition of 2

Preparation of pyridine-3,4-diols, their crystal packing and their use as precursors for palladium-catalyzed cross-coupling reactions

• Tilman Lechel,
• Irene Brüdgam and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, No. 42, doi:10.3762/bjoc.6.42

• palladium-catalyzed coupling reactions. Fluorescence measurements of the biscoupled products showed a maximum of emission in the violet region of the spectrum. Keywords: bisnonaflates; fluorescence; palladium catalysis; pyridine-3,4-diols; pyridines; Introduction Pyridine scaffolds have been found in

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

Fused bicyclic piperidines and dihydropyridines by dearomatising cyclisation of the enolates of nicotinyl-substituted esters and ketones

• Heloise Brice,
• Jonathan Clayden and
• Stuart D. Hamilton

Beilstein J. Org. Chem. 2010, 6, No. 22, doi:10.3762/bjoc.6.22

• deficient pyridines in the presence of trimethylsilyl triflate, tetrabutylammonium fluoride or a montmorillonite clay. The cyclisation precursor was synthesised by using the procedure of Hayashi [48] employing a Horner–Wadsworth–Emmons olefination between nicotinaldehyde and phosphonate 10. The resulting

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

• review. A related cationic Ru-vinylidene complex was used for an efficient alkynylation of pyridines with (alkyn-1-yl)trimethylsilane [98]. Based on these preliminary results, various catalytic propargylations of arenes have been developed, employing catalysts such as Mo/chloranil [16

Palladium- catalyzed cross coupling reactions of 4-bromo- 6H-1,2-oxazines

• Reinhold Zimmer,
• Elmar Schmidt,
• Michal Andrä,
• Marcel-Antoine Duhs,
• Igor Linder and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2009, 5, No. 44, doi:10.3762/bjoc.5.44

• -hexyne provided alkynyl-substituted pyridine derivative 12 thus demonstrating the potential of this approach for the synthesis of pyridines. Keywords: alkyne; halogenation; 1,2-oxazines; palladium catalysis; pyridines; Introduction A broad range of synthetic applications demonstrates that 1,2-oxazine