Synthesis of new pyrrole–pyridine-based ligands using an in situ Suzuki coupling method

• Matthias Böttger,
• Björn Wiegmann,
• Steffen Schaumburg,
• Peter G. Jones,
• Wolfgang Kowalsky and
• Hans-Hermann Johannes

Beilstein J. Org. Chem. 2012, 8, 1037–1047, doi:10.3762/bjoc.8.116

• , Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany 10.3762/bjoc.8.116 Abstract The compounds 6-(pyrrol-2-yl)-2,2‘-bipyridine, 2-(pyrrol-2-yl)-1,10-phenanthroline and 2-(2-(N-methylbenz[d,e]imidazole)-6-(pyrrol-2-yl)-pyridine were synthesized by using an in situ generated boronic

• substructures of common neutral ligands used in europium complex chemistry [6][9]: 2,2’-bipyridine and 1,10-phenanthroline. Compound 3 comprises a benzimidazole heterocycle, which was also used by the Bünzli group [1][2][3][4]. The synthesis of the resulting complexes was to date unsuccessful. We report here on

• hydrogen bond N17–H17…N1 involving the peripheral rings, which connects the molecules via the a-glide plane to form chains parallel to the a-axis. The structure of the methanol solvate of compound 2 is shown in Figure 3. The 1,10-phenanthroline ring system is planar (mean deviation 0.01 Å), and the pyrrole

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

• of the π-linker, particularly in chromophores 53–57, caused β enhancement up to 320 × 10−30 esu (Table 8). This clearly demonstrates the beneficial role of the thiophene as a polarizable unit and auxiliary electron donor. A combination of fused phenanthroline-imidazole acceptor moiety, N,N

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

• arylation of heterocycles, including electron-rich azoles with aryl bromides, by using potassium phosphate as a base and phenanthroline as a ligand (Scheme 8) [47]. Over the past few decades, it has also been demonstrated that copper catalysis is not required in order to attain good yield and selectivity in

• -formylthiophene by using Cu(I) cocatalyst and 1,10-phenanthroline in DMA solvent (Scheme 31a) [82]. This year, Oliaf studied more specifically the palladium- and copper-catalyzed oxidative C–H/C–H cross-coupling of various electron-rich 1,3-diazoles and reported notably the direct coupling of benzothiazole with

Impact of the level of complexity in self-sorting: Fabrication of a supramolecular scalene triangle

• Kingsuk Mahata and
• Michael Schmittel

Beilstein J. Org. Chem. 2011, 7, 1555–1561, doi:10.3762/bjoc.7.183

• various scalene triangles. It turned out that the self-sorting system with a higher level of complexity was far superior to less complex sorting algorithms. Keywords: copper; metallosupramolecular chemistry; phenanthroline; self-assembly; self-sorting; Introduction Self-assembly guided by self-sorting

• -coupling reactions [15]. A known procedure was followed to prepare the terpyridine–phenanthroline hybrid 7 [8]. The lengths of the ligands were chosen in such a way that they provide the geometrically different sides of a scalene triangle. Results and Discussion We tested both self-sorting algorithms as

• purification. The 1H NMR spectrum was found to be broad (Figure 3a). The broadening of the signals is partly due to the presence of a phenanthroline–Cu+–terpyridine complex. Due to the tetrahedral coordination behaviour of Cu+, one pyridine nitrogen atom of the terpyridine unit is left uncoordinated [30], and

CuCl-catalyzed aerobic oxidation of 2,3-allenols to 1,2-allenic ketones with 1:1 combination of phenanthroline and bipyridine as ligands

• Shuxu Gao,
• Yu Liu and
• Shengming Ma

Beilstein J. Org. Chem. 2011, 7, 396–403, doi:10.3762/bjoc.7.51

• under mild conditions. In this reaction CuCl (20 mol %) with 1,10-phenanthroline (10 mol %) and bipyridine (10 mol %) was used as the catalyst. It is interesting to observe that the use of the mixed ligands is important for the higher yields of this transformation: With the monoligand approach developed

• (1a) with O2 based on the pioneering study of oxidation of normal simple alcohols by Markó et al. [12]. Under the original conditions [12], the expected allenylic ketone 2a was obtained in 59% yield when CuCl and 1,10-phenanthroline were used (Table 1, entry 1). A series of bases and solvents were

• order to improve the yield further, we examined the effect of ligands. When 2,2'-bipyridine, which has a weaker coordinating ability, was used [36], the yield of 2a was lower (Table 3, entry 2). With 4,7-diphenyl-1,10-phenanthroline the yield was slightly improved to 66% (Table 3, entry 3). These

Recent advances in the development of alkyne metathesis catalysts

• Xian Wu and
• Matthias Tamm

Beilstein J. Org. Chem. 2011, 7, 82–93, doi:10.3762/bjoc.7.12

• achieved, all reactions required elevated reaction temperatures (≥ 80 °C) and, in most cases, high catalyst loadings (up to 20%). However, the results were greatly improved for the 1,10-phenanthroline (phen) systems 29/MnCl2 and 32/MnCl2 – MnCl2 is added to remove the phen-ligand by precipitation of MnCl2

• expense of higher catalyst loadings (10 mol %) and elevated reaction temperatures. In contrast, the phenanthroline–alkylidyne system 32 requires higher temperatures (80 °C) only for the activation with MnCl2, whereas the metathesis reaction can be carried out at ambient temperature. Noteworthy, it is the

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

• , was achieved by reacting 9-N-purines 91 with an excess of arylboronic acid 92 in the presence of copper(II) acetate, molecular sieves and phenanthroline (Scheme 22). Bakkestuen and Gundersen showed that electron-donating and electron-withdrawing substituents on the arylboronic acid were tolerated

• , reaction temperatures (90–115 °C) and reaction times (48 h) are comparable to the palladium-catalysed processes. Ligand-free and ligand-assisted reaction conditions have been applied in the synthesis of biologically active compounds. DMEDA, proline and phenanthroline are the most commonly used ligands. In

Recognition properties of receptors consisting of imidazole and indole recognition units towards carbohydrates

• Monika Mazik and
• André Hartmann

Beilstein J. Org. Chem. 2010, 6, No. 9, doi:10.3762/bjoc.6.9

• observed for 4 and 5 are quite different to those of the recently described phenanthroline/aminopyridine-based receptors 22 and 23 (see Figure 4) [27][29], which show a strong preference for α-glucoside and α-galactoside vs. the β-anomers. Thus, depending on the nature of the recognition units used as

• structure. In contrast to 4 and 5, the previously described phenanthroline/aminopyridine-based receptors 22 and 23 were shown to display a high binding affinity towards α-galactoside as well as a strong α- vs. β-anomer binding preference. Thus, depending on the nature of the recognition units incorporated

• -glucose [3], b) Amaranthus caudatus agglutinin with Galβ3GalNAc [1]. Structures of receptors 1–5. Structures of sugars investigated in this study. Structures of the recently described phenanthroline/aminopyridine-based receptors showing α- vs. β-anomer binding preferences in the recognition of glycosides