Dihydroanthracene, substituted

NXHOMO of the hydroxy-substituted dihydroanthracene is also symmetric in sign. Therefore, the antisymmetric orbital does not interact significantly with these vacant n orbitals of 36, resulting in an unperturbed n face of the carbonyl it orbital. This motif is regarded as an example of orbital non-interaction [105], Thus, the reduction of 2-methoxy and 3-methoxydibenzobicyclo[2.2.2]octadienones (34c and 34f) should intrinsically show little or no bias. 

Solvent Effects. The conversion of dihydroanthracene could be increased by adding water to the pyridine solvent (Table III). An 86% conversion to anthraquinone was obtained when 95% aqueous pyridine was used as the solvent. Furthermore, methanol could be substituted for the water with equivalent results. Other solvents were tried in place of pyridine (Table IV). The data indicate that 95% aqueous pyridine gave the best yields, although aniline gave nearly similar results. When acetonitrile and dimethylformamide were used, the large amounts of unreacted starting material indicate that these solvents may have deactivated the base by undergoing a hydrolysis reaction. 

Mahoney studied this kinetics by the oxidation of 9,10-dihydroanthracene inhibited by several substituted phenols [23,31,32,37,38,49]. 9,10-Dihydroanthracene possesses weak C—H bonds that are easily attacked not only by peroxyl radicals but also by phenoxyl radicals as well (for the rate constants of reaction (10), see Chapter 15). 

The name lepidopterene refers to the hydrocarbon 113 (L) whose butterflylike molecular shape was first revealed by X-ray diffraction analysis [129,130]. The structured electronic absorption spectra of lepidopterenes around 270 nm closely resemble that of 9,10-dihydroanthracene (see Figure 31). However, in terms of excited state properties, lepidopterenes have very little in common with 9,10-dihydroanthracene, which in solution fluoresces with a quantum yield of 0.16. By contrast, photoexcitation of lepidopterenes leads mainly to intramolecular exciplexes of 7i-chromophorically substituted anthracenes in an adiabatic process, for which both the molecular topology... 

The CD of a series of eight differently-substituted analogues of 9,10-ethano-9,10-dihydroanthracen-ll-one (142 and 143) was studied experimentally and theoretically329. Alteration of the substituent(s) on the benzene ring(s) affects the transition dipole magnitude and the transition energy of the aromatic chromophore without much change in the polarization direction. 

Csoregh, L, Brehmer, T, Bombicz, P. and Weber, E. (2001). Halogen... halogen versus OH... O supramolecular interactions in the crystal structures of a series of halogen and methyl substituted cw-9,10-diphenyl-9,10-dihydroanthracene-9,10-diols. Cryst. Eng. 4, 343-57. [272]... 

A synthesis of electrochemically amphoteric TTFAQ-ct-A derivatives 917 and 918 (TTFAQ = 9,10-bis(l,3-dithiol-2-ylidene)-9,10-dihydroanthracene, ct = saturated spacer, A = polynitrofluorene acceptor) involved esterification of the acid chloride 916 with the hydroxymethyl-substituted TTFAQ derivative 915 in pyridine. To increase acceptor properties, 917 was converted into the dicyanomethylene derivative 918 by reaction with malononitrile in DMF (Scheme 138) <2002JA14227>. 

The preferred orientation of the alkyl substituent in 9-alkyl-9,10-dihydroanthracenes is the pseudoaxial position (Me and Ph substituents occupy a pseudoequatorial position to some extent) (50), and the alkyl groups occupy the diaxial positions in m-9,10-dihydroanthracene derivatives (292). The favored conformation of the 10-substituted 10,H-dihydrodibenz[i,/]oxepins is that in which the 10-substituent is quasi-equatorial with respect to the seven-membered ring (187). In a study of the cis- and trawr-thioxanthenes, the lone pair was found to prefer the axial position (324) ... 

When Nu is electron donating the product is as a rule more easily oxidized than the starting material, resulting in further oxidation under the reaction conditions and, frequently, complex reaction mixtures. The anodic methoxylation of naphthalene, which results in 1-methoxy-, 1,2-dimethoxy-, and 1,4-dimethoxynaphthalene, approximately in a 1 2 1 ratio, serves as an illustration of this problem [67]. However, in other cases, a single major product is obtained after a sequence of reactions, such as the oxidation of mesitylene in MeCN-diluted H2SO4 to 2,4,6-trimethyl-4-hydroxycyclohexa-2,5-dien-l-one in a substitution-elimination reaction [68] or the oxidation of anthracene in MeOH to 9,9,10,l0-tetramethoxy-9,10-dihydroanthracene in a substitution-addition reaction [Eq. (28)] [69]. 

Catalytic hydrogenations over CojfCOjg (using Hj and CO) or with stoichiometric quantities of preformed hydridocarbonyl complex CoH(CO)4 are useful for the partial selective reductions of polycyclic aromatic compounds. Isolated benzene rings are not affected. Naphthalene is reduced to tetralin, at 200°C under a pressure of 20 X 10 kPa and anthracene to 9,10-dihydroanthracene (99%). The substituted phenanthrene nucleus is stable under these conditions as illustrated by hydrogenation of perylene 1 and pyrene 2. ... 

Benzynes and substituted benzynes react with isoindoles to give the 9,10-dihydroanthracene-9,10-imines (92).33 A considerable number of substituted compounds of this type have been prepared.27 Triptycene derivatives (i.e., the benzyne adducts of the anthracene system) have been encountered as unexpected products from the reaction of benzyne with 2-benzyl-1,3,4,7-tetramethylisoindole.114... 

The reason for this trend in going from 1,4-cyelohexadiene to 1,4-di-hydronaphthalene to 9,10-dihydroanthracene is that, while the ease of removal of the initial H-atom is expected to be about the same for each compound, ease of removal of the 3-H-atom in the resulting radical decreases with the increase in benzo substitution as shown in Table 3. Thus the removal of an H-atom from the hydroanthracene radical by oxygen is thermoneutral and the reaction is sufficiently slow so that the organic hydroperoxide route dominates. The reaction of 1,4-dihydro-naphthalene is intermediate. The reaction of the 1-hydronaphthyl radical with oxygen to form naphthalene is exothermic by 10 kcal mole 1 however, it is sufficiently slow so that, as the hydrocarbon concentration is increased, the organic peroxide product increases. 

Examples of photosubstitution reactions of parent aromatic hydrocarbons are rare. Methylated anthracenes and dihydroanthracenes are, however, afforded by the irradiation of anthracene in the presence of methyl-lithium.98 The isomer distribution of methyl-anthracenes thus produced is very different from that observed from the thermal reaction, and the process appears to be only successful with higher methyl-lithium concentrations than were previously used.97 The reaction is also reported to occur with naphthalene and phenanthrene.98 The efficiency of light-induced substitution reactions of methoxyanthraquinones with nucleophiles has been shown to be very dependent upon the position of the methoxy-group and the particular nucleophile.98 In general, the 1-methoxy-derivative is more reactive than the 2-isomer, and whereas reaction was observed... 

Carbon-silicon bond heterolysis from the radical cation of trimethylsilyl-substituted ethers, thioethers, and amines, generated by ET to DCA, is reported by Mariano et al. [60] to produce a corresponding methylene radical which ultimately combines with reduced DCA to yield the net photoaddition products 45 and 46, respectively. Photoaddition of Me3SiN(Et)2 initially produces corresponding dihydroanthracene adduct (47), which spontaneously dehydrocyanates under the reaction condition to give (48) (Scheme 11). 

Beckett, A. H. Walker, J. Steric interactions in substituted cyclohexadienes. II. Meso-substituted dihydroanthracenes steric effects in the reactions of cis and trans isomers. Tetrahedron 1963,19, 545-556. 

The complex exhibits the normal characteristic features of mono-arene Ru(II) complexes an alternation of the lengths of the C-C bonds for the coordinated arene and irregular Ru-C bond lengths, with the longest of 2.244 A (compared with 2.137 A for the shortest) being for the carbon attached to the phenyl substitutent. Coordinated arenes with extended ring systems can have a flexible structure, as illustrated for dihydroanthracene (DHA) complexes in Table 2.2 (vide infra). Such arene flexibility may play a role in interactions of Ru(II) arene complexes with DNA. 

Photo-oxygenation of 7,12-dimethylbenz[a]anthracene gave the bicyclic acetal (347), while 9-methyl-anthracenes with a free 10-position undergo substitution when they react with a phenyl radical, leading to 9-methylene-10-phenyl-9,10-dihydroanthracene (348). ... 

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