Templated versus non-templated synthesis of benzo-21-crown-7 and the influence of substituents on its complexing properties

• Wei Jiang and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2010, 6, No. 14, doi:10.3762/bjoc.6.14

• with the larger anthracene π-system in 5-H•PF6. Analogously, stronger binding of C7 would be expected with 7-H•PF6 as compared to 6-H•PF6. Surprisingly, the binding affinities of C7 or 4 toward anthracenyl methyl-substituted 7-H•PF6 turn out to be lower than to benzyl-substituted 6-H•PF6. There are two

• dialkylammonium guests significantly alter the binding ability. Replacing a benzyl stopper on the axle by an anthracenyl methyl group even changes the binding mode: Formation of C-H•••O hydrogen bonds is hampered for the methylene group between the anthracene and the ammonium. Compared to DB24C8, the complexing

A stable enol from a 6-substituted benzanthrone and its unexpected behaviour under acidic conditions

• Marc Debeaux,
• Kai Brandhorst,
• Peter G. Jones,
• Henning Hopf,
• Jörg Grunenberg,
• Wolfgang Kowalsky and
• Hans-Hermann Johannes

Beilstein J. Org. Chem. 2009, 5, No. 31, doi:10.3762/bjoc.5.31

• [benzo[de]anthracene-6,9′-fluoren]-7-ol (11), Bicyclo[4.3.1]decane derivative 12, and 6-(Biphenyl-2-yl)-5,6-dihydro-4H-benzo[de]anthracen-7-ol (13) The enol 4 (500 mg, 1.30 mmol) was dissolved in warm toluene (20 mL). Phosphoric acid (0.5 mL) and silica gel (1.0 g) were added and the mixture was stirred

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

• for the cycloaddition of maleimide to anthracene in toluene (Scheme 5). Table 3 summarizes the results. A significantly higher yield of the cycloaddition product was obtained after 8 h at 40 °C in the presence of compound 2 (entry 3), if compared to the control reaction (entry 6). Upon irradiation

• reaction (entry 4). Blue light irradiated flavins accelerate the anthracene maleimide cycloaddition significantly, but flavins 1 and 2 do not provide additional benefit if compared to tetraacetyl flavin 3. Conclusion We have prepared new flavin derivatives that bear an acyl guanidinium group, which is

• )2, mono-Boc guanidine, CH2Cl2, rt, 20 h, 58–82%, (iii) HCl/Et2O, CH2Cl2/CHCl3, rt, 24 h, 83–90%. Oxidative photocleavage of dibenzyl phosphate. Photoreduction of 4-nitrophenyl phosphate. Photo Diels–Alder-reaction of anthracene with N-methyl-maleinimide. Oxidative photocleavage of dibenzyl phosphate

Reversible intramolecular photocycloaddition of a bis(9-anthrylbutadienyl)paracyclophane – an inverse photochromic system. (Photoactive cyclophanes 5)

• Henning Hopf,
• Christian Beck,
• Jean-Pierre Desvergne,
• Henri Bouas-Laurent,
• Peter G. Jones and
• Ludger Ernst

Beilstein J. Org. Chem. 2009, 5, No. 20, doi:10.3762/bjoc.5.20

• cycles were recorded but the photoproduct could not so far be isolated. It occurred to us that the performance of these systems could be improved by incorporating the anthracene substrate, well known for its ability to generate definite photodimers [10][11][12][13][14][15], in the pseudo-gem positions of

• diffusion of pentane vapour. The molecular structure of 2 is presented in Figure 4. The double bonds are clearly all-trans and their average planes form twist angles with the two anthracene nuclei of 47° and 44°,respectively; the two ethylenic systems are also not parallel to each other but subtend twist

• angles of 42–43° (see Table 1). Finally, the interplanar angle between the two anthracene substrates is ca 4.5° (Table 1). Consequently, the inter-ring distance varies between 3.40 and 3.80 Å. Two lateral anthracene nuclei are thus in close proximity (see Figure 5), in which two carbons are separated by

Highly brominated anthracenes as precursors for the convenient synthesis of 2,9,10-trisubstituted anthracene derivatives

• Osman Cakmak,
• Leyla Aydogan,
• Kiymet Berkil,
• Ilhami Gulcin and
• Orhan Buyukgungor

Beilstein J. Org. Chem. 2008, 4, No. 50, doi:10.3762/bjoc.4.50

• tribromide 12 was transformed to trimethoxy compound 13 and trinitrile 14 by copper-assisted nucleophilic substitution reactions. Keywords: anthracene derivative; bromination; bromoanthracene; cyanoanthracene; methoxyanthracene; Introduction Anthracene derivatives have been extensively investigated in many

• biological systems, anthracene skeletal compounds are also useful for probing DNA cleavage [17]. Bromoanthracenes have become increasingly important in the synthesis of anthracene derivatives [18]. For example, new anthracene derivatives used as light emitting material in a non-doped organic light-emitting

• diode (OLED) were synthesized from the corresponding bromo derivatives by substitution [19][20][21][22][23]. Recently we succeeded in the bromination of anthracene to give hexabromides 3 and 4 which were used in the selective and specific preparation of anthracene oxides and anthracene derivatives

Synthesis of 2,3,6,7-tetrabromoanthracene

• Christian Schäfer,
• Friederike Herrmann and
• Jochen Mattay

Beilstein J. Org. Chem. 2008, 4, No. 41, doi:10.3762/bjoc.4.41

• . Keywords: anthracene; arenes; cyclizations; polycycles; ring closure; 2,3,6,7-tetrabromoanthracene; Introduction Anthracene and its derivatives are long known polycyclic aromatic compounds showing a high potential for use in materials science (e.g. fluorescence probing, photochromic systems

• , electroluminescence) and several reviews have been published so far [1][2][3]. Anthracenes may be readily functionalized in positions 9 and 10 due to their exceptional reactivity. The outer rings, however, can not be functionalized easily. There are some anthracene compounds available with one or two substituents at

• -cyclohexadiene as hydrogen donor. In this case, the structure and the purity of 4 were proven by NMR and high resolution mass spectrometry. The UV/VIS-spectra of 2,3,6,7-tetrabromoanthracene and anthracene in cyclohexane are shown in Figure 1. At first glance, both spectra resemble each other; however, all

The role of an aromatic group in remote chiral induction during conjugate addition of α-sulfonylallylic carbanions to ethyl crotonate

• Shlomo Levinger,
• Ranjeet Nair and
• Alfred Hassner

Beilstein J. Org. Chem. 2008, 4, No. 32, doi:10.3762/bjoc.4.32

• ]. 9-Acetylanthracene does not lend itself to the Borch reductive amination, which entails a nucleophilic addition step of ammonia (or amine) to the carbonyl function [7]. Conjugation between the anthracene nucleus and an acyl substituent at position 9 is sterically inhibited by the flanking hydrogen

• for orthogonality between the planar function and the aromatic nucleus in the nitrogen derivatives of 9-acylanthracenes has been corroborated spectroscopically (lack of conjugation in the semicarbazide and the oxime). Furthermore, steric hindrance to attack at the cyano group of anthracene-9

• anthracene) is also worth noting in this context. Restricted rotation in acylnaphthalenes has been extensively studied [11]. Amino-substituted allyl sulfones 1 were deprotonated with LDA at −78 °C in THF and the lithio derivative obtained was allowed to react for a specified time at that temperature with