Highly Substituted Anthracenes

Benzannulated anthracenes 110a, 110b, and 110c (Fig. 31) are highly twisted with end-to-end twists of 66°, 61°, and 70°, respectively [94, 95]. Similarly, crowded anthracenes 111 and 112 show twists of 60° and 57°, respectively [96]. 

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Another approach for the development of PET-based molecular indicators for detection of nerve agents utilizes phosphorylation of an amine functionality, which is integrated into the structure of a fluorophore. This principle is used in the case of highly substituted anthracene bisimide (Figure 16.17f) [51] and fluoresceinamine (Figure 16.17g) [52]. These sensory compounds can be easily incorporated into polymer matrices [51] or deposited onto the surface of silica beads [52], thus yielding solid state detectors. 

Roberts G G, McGinnity M, Barlow W A and Vincett P S 1979 Electroluminescence, photoluminescence and electroabsorption of a highly substituted anthracene Langmuir film Solid State Common. 32 683-6... 

Several groups have studied naphthalene substituted anthracene derivatives as hosts or emitter materials in blue OLEDs (121, 202-205) (Scheme 3.63). The Kodak group used ADN as a host and TBP as a dopant in ITO/CuPc/NPD/ADN TBP/Alq3/Mg Ag [241]. They achieved a narrow vibronic emission centered at 465 nm with CIE (0.154, 0.232) and a luminescent efficiency as high as 3.5 cd/A. In comparison, the undoped device shows a broad and featureless bluish-green emission centered at 460 nm with CIE (0.197, 0.257) and an EL efficiency below 2.0 cd/A. The operational lifetimes of the doped device and the undoped device were 4000 and 2000 h at an initial luminance of 636 cd/m2 and 384 cd/m2, respectively. 

In the syntheses of these compounds, very high stereoselectivity was noted. In every case, the entering dienophile approaches the least hindered side of the substituted anthracene. Thus tire ap isomer is the almost exclusive product of the reaction. As an extension of this finding, atropisomers of 9-(l,I-dimethyl-2-phenylethyl)-2,3-dichlorotriptycene (101) were prepared separately the ap form by treating 9-( 1,1 -dimethyl-2-phenylethyl)anthracene with 4,5-dichlorobenzyne, and the sc form by treating 2,3-dichloro-9-(l,l-dimethyl-2-phenylethyl)-... 

Microwave-assisted Diels-Alder reactions of 9-substituted anthracenes with 2-acetamidoacrylate in DMF generate conformationally constrained bicyclic bisaryl a-amino acid derivatives with high regioselectivity.138 The Sc(OTf)3-catalysed Diels-Alder reaction of anthracenes with methyl vinyl ketone does not proceed via an electron-transfer process from anthracenes to the MVK-Sc(OTf)3 complex.139 (-)-(/ )-9-(l,2-Dimethoxyethyl)anthracene has been used as a chiral template in the Diels-Alder/retro-Diels-Alder sequence for the synthesis of a,j3-unsaturated lactams.140... 

The photochemistry and photophysics of 2-methyl, 2-ethyl, and 2-tert-butylanthracenes on silica gel was examined by Dabestani et al. [38] to assess the substituent effect on product distribution and mechanism. In contrast to anthracene, which forms ground-state pairs at very low surface coverages (1% of a monolayer) [39], substituted anthracenes show no evidence of pairing even at surface coverages as high as 53% of a monolayer. Further-... 

High resolution NMR has been used to investigate the photo-dimerisation of 9-methylanthracene. In the solid state, only the trans dimer is formed whereas in benzene solution both the trans and cis dimers are produced. Studies show that the maximum domain size of the minor component is about 0.3 pm, and that the reaction occurs at crystal defects in the monomer. Photodimerisation of the 9-substituted anthracenes An-CHzN- MejBr- (166), AnCH2C02 Na-" (167), AnCH20H (168), AnCOMe... 

Wang and co-workers also evaluated the reactivity of 9-substituted anthracene in Diels-Alder reactions with fullerene. Corresponding adducts were prepared in high yields under solvent-free conditions using the high-speed vibration milling technique (Scheme 8.14). ... 

Elimination of HCl from 1-cholorquadricyclane (121) leads to transient olefin 122, which can be captured by anthracene to furnish the highly substituted [4.2.1]propellane 123. The X-ray structure of 123 indicates that the bridgehead carbon atoms of the propellane system are very slightly inverted the plane of the three starred substituents of the nearer bridgehead passes 0.05 A behind the bridgehead. The necessary rehybridization is apparently sufficient to lead to typical propellane reactions, and 123 adds thiophenol readily to form 124 . Related adducts form with substituted anthracenes. The parent [4.2.1]propellane is also known and is little more reactive than bicydo[2.1.0]hexane from which it is formally derived... 

Fukutani T, Hirano K, Satoh T, Miura M (2009) Synthesis of highly substituted naphthalene and anthracene derivatives by rhodium-catalyzed oxidative coupling of arylboronic acids with alkynes. Org Lett 11 5198-5201. doi 10.1021/ol9021172... 

Karatsu T, Hazuku R, Asuke M, Nishigaki A, Yagai S, Suzuri Y, Kita H, Kitamura A (2007) Blue electroluminescence of silyl substituted anthracene derivatives. Oig Electron 8 357-366 Kelley TW, Muyres DV, Baude PF, Smith TP, Jones TD (2003) High performance organic thin film transistors. Mater Res Soc Symp Proc 771 169-179... 

Trimethylsilylmethyl substituted benzenes have low first ionization potentials and if below 7.8 eV can be oxidized by AlClj-CHaCla to the radical cation. The e.s.r, data supports delocalization and, with p.e. and CT data, helps to elucidate the structure of preferred conformers of highly substituted benzenes. The radical cations of biphenyl and anthracene have been prepared similarly, but are only stable below - 80 °C. ... 

Generally, the Vilsmeier reaction fails for benzene, alkylbenzenes and naphthalene. The reaction gives low yields in the case of phenol ethers if the para-position is already occupied and fails for highly substituted benzofurans, indicating that the presence of a sufficiently reactive (labile) hydrogen atom on the aromatic ring is necessary for successful application. However, Martinez et al. reported the formylation of 1,3,5-trimethylbenzene, naphthalene, acenaphthene, anthracene and phenanthrene in fair yield using the trifluoromethanesulphonic anhydride/dimethylformamide complex (Eq 1.29). 

This is consistent with the observed products of oxidation, i.e. benzyl alcohol, benzaldehyde and benzoic acid and with the observed oxidation of cyclohexane. Radical-cations are, however, probably formed in oxidation of napthalene and anthracene. The increase of oxidation rate with acetonitrile concentration was intepreted in terms of a more reactive complex between Co(III) and CH3CN. The production of substituted benzophenones at high CH3CN concentration indicates the participation of a second route of oxidation. 

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