Iodination of carbohydrate-derived 1,2-oxazines to enantiopure 5-iodo-3,6-dihydro-2H-1,2-oxazines and subsequent palladium-catalyzed cross-coupling reactions

• Michal Medvecký,
• Igor Linder,
• Luise Schefzig,
• Hans-Ulrich Reissig and
• Reinhold Zimmer

Beilstein J. Org. Chem. 2016, 12, 2898–2905, doi:10.3762/bjoc.12.289

• of the mono- and bisalkynyl-substituted 6H-1,2-oxazines was additionally demonstrated by Lewis-acid-mediated conversion into highly substituted pyridine derivatives [25] by cycloaddition of in situ generated azapyrylium intermediates [26] and alkynes. Inspired by these previously reported results, we

One-pot synthesis of tetracyclic fused imidazo[1,2-a]pyridines via a three-component reaction

• Bo Yang,
• Chuanye Tao,
• Taofeng Shao,
• Jianxian Gong and
• Chao Che

Beilstein J. Org. Chem. 2016, 12, 1487–1492, doi:10.3762/bjoc.12.145

• ]pyridine derivatives. Reaction conditions: 2 (1.35 mmol), 3 (1 mmol), 4 (1.35 mmol), HClO4 (1 mmol), n-BuOH (4 mL), reflux. Yields refer to isolated yields. 2b R1 = 4-Cl; 2c R1 = 4-Me, 2d R1 = 4-Br; 3b R2 = 5-OMe; 3c R2 = 5-Cl; 3d R2 = 5-Br; 3e R2 = 5,7-Me2; 3f R2 = 7-F; 3g R2 = 5-I; 4b R3 = cyclohexyl

• . Mechanistic rationale for the MCR [36]. MCR to polycyclic fused imidazo[1,2-a]pyridine derivatives. Synthesis of imidazo[1,2-a]pyridine derivatives in indicated conditions [36].a Supporting Information Supporting Information File 576: Experimental procedures, characterization and spectral data for

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

• -phosphonates and 2-acyl-1,2-dihydroisoquinoline-1-phosphonates. Three-component reaction of pyridine derivatives with ethyl propiolate and dialkyl phosphonates. Three-component reactions for the phosphorylation of benzothiazole and isoquinoline. Three-component synthesis of diphenyl [2-(aminocarbonyl)- or [2

Synthesis of highly functionalized 2,2'-bipyridines by cyclocondensation of β-ketoenamides – scope and limitations

• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1170–1177, doi:10.3762/bjoc.12.112

• or O-nonaflation led to functionalized pyridine derivatives. Scheme 1 illustrates this sequence with the synthesis of two 2,2´-bipyridine derivatives 4a or 5b that were obtained by employing picolinic acid chloride for the N-acylations followed by O-methylation with methyl iodide or by O-nonaflation

• using nonafluorobutanesulfonyl fluoride (NfF) as sulfonylating reagent. In subsequent publications we could demonstrate that this method can be used to synthesize a variety of functionalized pyridine derivatives, 2,2´-bipyridines or terpyridines [2][3][4]. An alternative entry to the crucial β

• carboxylic acids [33][34][35][36][37][38][39][40]. These components form α-alkoxy-substituted β-ketoenamides as precursors of highly substituted pyridine derivatives. We therefore tried to independently prepare β-ketoenamides with this substitution pattern starting from simple 1,3-diketones such as 1a. An

A convergent, umpoled synthesis of 2-(1-amidoalkyl)pyridines

• Tarn C. Johnson and
• Stephen P. Marsden

Beilstein J. Org. Chem. 2016, 12, 1–4, doi:10.3762/bjoc.12.1

• . Although the regioselectivities are not exceptionally high, the ready chromatographic separation of the various isomers makes this a synthetically tractable approach to 4-substituted (1-amidoalkyl)pyridine derivatives. Conclusion In summary, we have demonstrated a new umpoled disconnection for the one-pot

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• ]. The synthesis of a small collection of imidazo[1,2-a]pyridine derivatives was realised through the application of different scavenger resins for in-line purification as well as a number of liquid handlers to orchestrate the library synthesis effort (Scheme 24). Using this semi-automated process a

The reactions of 2-ethoxymethylidene-3-oxo esters and their analogues with 5-aminotetrazole as a way to novel azaheterocycles

• Marina V. Goryaeva,
• Yanina V. Burgart,
• Marina A. Ezhikova,
• Mikhail I. Kodess and
• Viktor I. Saloutin

Beilstein J. Org. Chem. 2015, 11, 385–391, doi:10.3762/bjoc.11.44

• . Thus, we have found an effective and simple reaction for the preparation of substituted pyrimidine and pyridine derivatives. The resulting compounds are important pharmacophores or may be used as a starting material for synthesis of other functionalized pyrimidines through nucleophilic substitution. X

One-pot four-component reaction for convenient synthesis of functionalized 1-benzamidospiro[indoline-3,4'-pyridines]

• Chao Wang,
• Yan-Hong Jiang and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2014, 10, 2671–2676, doi:10.3762/bjoc.10.281

• reactions [19][20][21]. Recently, we and Perumal have demonstrated that the four-component reaction of arylamine, acetylenedicarboxylate, isatin and malononitrile can afford the spiro[indoline-3,4’-pyridine] derivatives in satisfactory yields [22][23][24]. We envisioned that functionalized spiro[indoline

• -3,4’-pyridine] derivatives can be synthesized by employing other nitrogen-containing nucleophiles such as hydrazine and imines in the similar four-component reactions. In fact, the four-component reaction of hydrazine, acetylenedicarboxylate, isatin and malononitrile for the formation of spiro

• four-component reaction for the efficient synthesis of the functionalized spiro[indoline-3,4’-pyridine] derivatives [23] a mixture of benzohydrazide and dimethyl acetylenedicarboxylate in ethanol was firstly stirred at room temperature for about fifteen minutes. Then isatin and malononitrile as well as

Streptopyridines, volatile pyridine alkaloids produced by Streptomyces sp. FORM5

• Ulrike Groenhagen,
• Michael Maczka,
• Jeroen S. Dickschat and
• Stefan Schulz

Beilstein J. Org. Chem. 2014, 10, 1421–1432, doi:10.3762/bjoc.10.146

• . Keywords: headspace analysis; natural products; polyketide biosynthesis; pyridine derivatives; streptazolin; volatile compounds; Introduction Actinomycetes are excellent producers of diverse and bioactive secondary metabolites. These metabolites belong to many different structural classes including

• . Natural products of bacteria containing a pyridine ring are rare. As an example, 1-(2-pyridinyl)ethanone was identified as a volatile of Enterobacter agglomerans [20]. Highly substituted pyridine derivatives can be found in bacterial thiopeptide antibiotics [21]. The streptopyridines of Streptomyces sp

• the production of other, usually less volatile secondary metabolites and whether different compounds can be detected by headspace analysis [7] compared to commonly used solvent extraction or adsorption/extraction procedures. Strain FORM5 has been reported to produce the tetrahydrocyclopenta[b]pyridine

The Flögel-three-component reaction with dicarboxylic acids – an approach to bis(β-alkoxy-β-ketoenamides) for the synthesis of complex pyridine and pyrimidine derivatives

• Mrinal K. Bera,
• Moisés Domínguez,
• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 394–404, doi:10.3762/bjoc.10.37

• 15 however, the cyclization was complete under these conditions furnishing bis(pyrimidine) derivative 25 as a single product in 60% yield. Although initially not desired the incomplete conversions of the bis(β-ketoenamides) leading to mono-pyridine derivatives such as 18b or to mono-pyrimidine

Synthesis, characterization and luminescence studies of gold(I)–NHC amide complexes

• Adrián Gómez-Suárez,
• David J. Nelson,
• David G. Thompson,
• David B. Cordes,
• Duncan Graham,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2013, 9, 2216–2223, doi:10.3762/bjoc.9.260

• moderate emission intensity (ca. 10–50 AU). The most intense fluorescence was observed with complexes 3, 6 and 10: 2-pyridine derivatives without electron-withdrawing substituents (ca. 120–290 AU) (Table 1). DFT calculations were used to probe the nature of the frontier orbitals of complex 3 (at the M06-L

• fluorescence behavior of these materials, with more electron-rich 2-pyridine derivatives showing strong emission, and isoquinoline-derived complexes showing the strongest fluorescence. While the present study has been conducted using commercial reagent-grade amines, there is significant scope to prepare a much

One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor

• Mark C. Bagley,
• Vincenzo Fusillo,
• Robert L. Jenkins,
• M. Caterina Lubinu and
• Christopher Mason

Beilstein J. Org. Chem. 2013, 9, 1957–1968, doi:10.3762/bjoc.9.232

• synthetic procedures to a continuous flow processing regime in a microwave flow reactor seemed highly feasible to access pyridine derivatives in a single step. Results and Discussion Synthesis of pyridines in a continuous flow reactor Many of our previous studies on the synthesis of pyridines in a

• of pyridine derivatives and, for the Bohlmann–Rahtz pyridine synthesis, give improved performance over a comparable large scale multimode batch experiment. This expands the growing set of heterocyclic targets that have been accessed by the reactions of ethynyl ketones under continuous flow processing

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

• Crystallographic Data Centre. General procedure for the synthesis of spiro[indoline-3,4’-pyridine] derivatives 1a–1p: In an analogous manner to our procedure published in [25], a solution of arylamine (2.0 mmol), methyl propiolate (2.0 mmol) in 5 mL ethanol was stirred at room temperature overnight. Then isatin

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

• acidic and oxidative conditions would then afford the highly substituted dihydropyridine or pyridine derivatives 5 and 6, respectively. While there were no examples of such exclusive anionic 6-endo-dig cyclizations reported to the best of our knowledge [39], we felt that the presence of the chelating

Expanding the chemical diversity of spirooxindoles via alkylative pyridine dearomatization

• Chunhui Dai,
• Bo Liang and
• Corey R. J. Stephenson

Beilstein J. Org. Chem. 2012, 8, 986–993, doi:10.3762/bjoc.8.111

• ]oxazino derivatives from N-substituted isatins and 1,3-dicarbonyl compounds with pyridine derivatives is reported. The reactions provided good to excellent yields. Further exploration of the molecular diversity of these compounds is demonstrated through Diels–Alder reactions. Keywords: chemical diversity

• 5 in pyridine. Reactions of vinylogous sulfonyl esters 6 with pyridine derivatives 7. Supporting Information Supporting Information File 112: Full experimental details and analytical data and crystallographic information. Acknowledgements Financial support for this research from the NIH-NIGMS (P50

Toward unidirectional switches: 2-(2-Hydroxyphenyl)pyridine and 2-(2-methoxyphenyl)pyridine derivatives as pH-triggered pivots

• Christina Tepper and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2012, 8, 977–985, doi:10.3762/bjoc.8.110

• Christina Tepper Gebhard Haberhauer Institut für Organische Chemie, Fakultät für Chemie, Universität Duisburg-Essen, Universitätsstraße 7, D-45117 Essen, Germany 10.3762/bjoc.8.110 Abstract The pH-induced switching process of 2-(2-hydroxyphenyl)pyridine and 2-(2-methoxyphenyl)pyridine derivatives

• for molecular devices [49][50][51][52][53][54][55][56], 2-(2-hydroxyphenyl)pyridine and 2-(2-methoxyphenyl)pyridine derivatives, to our best knowledge, have only been used as ligands for metal complexes, but not for the construction of molecular switches [57][58][59][60][61][62][63]. Similar compounds

• unidirectionality is small. Conclusion In sum we were able to show that 2-(2-methoxyphenyl)pyridine and 2-(2-hydroxyphenyl)pyridine derivatives can successfully be used as pivots. According to the calculated energy profiles, the rotation movements during the switching of the corresponding 3-methyl derivatives

Enaminones in a multicomponent synthesis of 4-aryldihydropyridines for potential applications in photoinduced intramolecular electron-transfer systems

• Nouria A. Al-Awadi,
• Maher R. Ibrahim,
• Mohamed H. Elnagdi,
• Elizabeth John and
• Yehia A. Ibrahim

Beilstein J. Org. Chem. 2012, 8, 441–447, doi:10.3762/bjoc.8.50

• -piperidinoacrylonitrile (13) with the appropriate aldehyde and primary amine under the same reaction conditions (A, B) (Scheme 4). Compounds 2a–c and 6a were readily oxidized to the corresponding pyridine derivatives 15a–d by stirring in aqueous nitric acid (70%) at 5 °C to room temperature (Scheme 5). The X-ray

Syntheses and applications of furanyl-functionalised 2,2’:6’,2’’-terpyridines

• Jérôme Husson and
• Michael Knorr

Beilstein J. Org. Chem. 2012, 8, 379–389, doi:10.3762/bjoc.8.41

• describes the state of the art concerning preparation and applications of such terpyridines bearing a furanyl ring. Review Synthesis by ring closure of 1,5-diketones In 1976, Kröhnke introduced a synthetic methodology to prepare pyridine derivatives that relies on the ring closure of 1,5-diketo-derivatives

Synthesis and characterization of new diiodocoumarin derivatives with promising antimicrobial activities

• Hany M. Mohamed,
• Ashraf H. F. Abd EL-Wahab,
• Ahmed M. EL-Agrody,
• Ahmed H. Bedair,
• Fathy A. Eid,
• Mostafa M. Khafagy and
• Kamal A. Abd-EL-Rehem

Beilstein J. Org. Chem. 2011, 7, 1688–1696, doi:10.3762/bjoc.7.199

• – CO2, 7.3), 425 (M – NH-C6H4-4-CH2COOH, 13.5), 424 (100), 341 (18.9), 171 (27.2), 106 (94.6) and 87 (59.5). General procedure for the synthesis of ethyl cyanoacetate and pyridine derivatives 12 and 13 Ethanolic solution of ethyl 6,8-diiodocoumarin-3-carboxylate (1) (0.47 g, 10 mmol, 30 mL) was refluxed

• derivatives 1–7. Proposed fragmentation pathways for the EI ions of the substituted 6,8-diiodocoumarins 3 and 7. Synthesis of 6,8-diiodocoumarin-3-N-carboxamide derivatives 8–11. Synthesis of ethyl cyanoacetate and pyridine derivatives 12 and 13. Synthesis of 1,3-oxazocine derivatives 14a,b. Biological

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

• Verona, Italy 10.3762/bjoc.7.170 Abstract In a simple procedure, the intramolecular hydroarylation of N-propargyl-pyrrole-2-carboxamides was accomplished with the aid of gold(III) catalysis. The reaction led to differently substituted pyrrolo[2,3-c]pyridine and pyrrolo[3,2-c]pyridine derivatives arising

• hydroarylation of alkynyl-tethered pyrrole-2-carboxamides in order to have an alternative protocol to access pyrrolo-fused pyridine skeletons. The importance of pyrrolo[2,3-c]pyridine and pyrrolo[3,2-c]pyridine derivatives from the biological point of view [36][37][38][39][40][41][42][43][44][45][46][47][48][49

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• excellent yields (Scheme 8). Another strategy allowing access to pyridine derivatives was developed by Katsumura and coworkers. They showed that chiral 2,4-disubstituted 1,2,5,6-tetrahydropyridines 17 can be obtained through a one pot imine synthesis, Stille coupling, 6π-azaelectrocyclization 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

• : Enantioselective reduction of pyridine carbonyl compounds, the addition of lithiated pyridine derivatives to chiral ketones or the resolution of racemates being the most common approaches. The preparation of chiral pyridine derivatives starting from simple enantiopure precursors is less common [27][28]. Recently

• [35][36]. In the past, we devoted considerable interest to the synthesis of substituted pyridine derivatives by this route and investigated their use in subsequent transformations [37][38][39]. Broadening the scope of the process to functionalized, chiral starting materials is the subject of this

• carboxylic acids, enantiopure nitriles were also successfully converted into pyridine derivatives in comparable yields. As an example, (S)-2-methylbutyronitrile (31) could be converted into compound 40 in good yield. The use of carboxylic acids and nitriles with structurally identical substituents allows a

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

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

• ][15][16][17], we focused on the synthesis of trifluoromethyl-substituted pyridine derivatives [18][19][20][21][22][23]. Herein, we report different methods for the deprotection of a range of 3-alkoxypyridinols 1 to give pyridine-3,4-diols 2 and the corresponding tautomers 2′. This equilibrium between

• extended π-systems using palladium-catalyzed coupling reactions. Moreover, compounds 4b–c show interesting photophysical properties that might be thoroughly investigated in the future. The 3,4-dialkynyl-pyridine derivatives 4 or 5 are also candidates for Bergman cyclizations [34][35] which may establish a

Solvent-free and time-efficient Suzuki–Miyaura reaction in a ball mill: the solid reagent system KF–Al₂O₃ under inspection

• Franziska Bernhardt,
• Ronald Trotzki,
• Tony Szuppa,
• Achim Stolle and
• Bernd Ondruschka

Beilstein J. Org. Chem. 2010, 6, No. 7, doi:10.3762/bjoc.6.7

• neutral to basic aluminas has been recently shown in three-component reactions affording thiochromeno[2,3-b]pyridine derivatives [24]. The results were in clear contrast to that of the microwave-assisted Pd(PPh3)4-catalyzed solid-state Suzuki–Miyaura reaction protocol presented by Saha et al., revealing