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

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

• pyridine derivatives: a) BF3·OEt2, CH2Cl2, −78 °C to r.t., overnight. Acknowledgments Generous support by the Deutsche Forschungsgemeinschaft (Graduiertenkolleg at the Technische Universität Dresden “Struktur–Eigenschafts-Beziehungen bei Heterocyclen”), the Fonds der Chemischen Industrie and the Bayer

• treatment of 9c with boron trifluoride etherate in the presence of an excess of 1-hexyne via an azapyrylium intermediate [34][35]. Additional investigations are required to optimize the preparation diynes of type 11. Conversion of the new functionalized 6H-1,2-oxazines to highly substituted pyridine

• derivatives will also be reported in due course. Experimental Bromination of 6H-1,2-oxazine 1a, typical procedure 6H-1,2-Oxazine 1a (5.35 g, 26.3 mmol) was dissolved in diethyl ether (200 mL) and treated with bromine (2.75 mL, 53.7 mmol) at −30 °C under argon atmosphere. After 2 h Et3N (54.0 mL, 390 mmol) was

Regioselective alkynylation followed by Suzuki coupling of 2,4-dichloroquinoline: Synthesis of 2-alkynyl- 4-arylquinolines

• Ellanki A. Reddy,
• Aminul Islam,
• K. Mukkanti,
• Venkanna Bandameedi,
• Dipal R. Bhowmik and
• Manojit Pal

Beilstein J. Org. Chem. 2009, 5, No. 32, doi:10.3762/bjoc.5.32

• )2PdCl2-CuI or treatment of 4-aryl pyridine-N-oxide with alkynyl Grignard [5] provided the required quinoline or pyridine derivatives, respectively. Notably, synthesis of A following the strategy ‘b’ has not been explored. In our effort towards the synthesis of quinoline derivatives of potential

Diastereoselective synthesis of some novel benzopyranopyridine derivatives

• Pradeep K. Mohakhud,
• Sujeet M. R. Kumar,
• Vasanth M. R. Kumar,
• Ravi M. R. Kumar,
• Moses D. R. Babu,
• Vyas D. R. K and
• Om D. R. Reddy

Beilstein J. Org. Chem. 2006, 2, No. 25, doi:10.1186/1860-5397-2-25

• enantiomers 7a and 7b. The absolute configuration is determined by single crystal X-ray analysis of the mandelate salt. General structures A & B, Tetrahydro cannabinole derivatives. General structures C & D, Benzopyrano pyridine derivatives. Proposed mechanism of tetrahydropyridine formation, Proposed