Reduced Anthracenes

Polycyclic Aromatic Compounds and Their Reduction Products 

Sestanj, F. Bellini, S. Fung, N. Abraham, A. Treasurywala, L. Humber, N. Simard-Duquesne, and D. Dvomik, J. Med. Chem., 27,255, (1984), 

Kojima, K. Niigata, T. Fujikura, S. Tachikawa, Y. Nozaki, S. Kagami, and K. Taka-hashi, Chem. Pharm. Bull., 33,3766 (1985). 

Austrian Patent, AT 368,125B (1982) via Chem. Abstr., 98 4,405g (1982). 

Wilhelm, R. Bernasconi, A. Stomi, D. Beck, and K. Schenker, Patentschrift (Switz.), 558,774 (1975) via Chem. Abstr., 83 96,859z (1975). 

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Attempts to reduce anthracene with an alkali metal in acetonitrile causes solvent decomposition, whereas controlled-potential electrolysis produces stable anion radicals. Thus the working electrode of a coulometric cell can be considered as a continuously adjustable reagent, capable of producing a wide variety of radical species in diverse solvent systems. The versatility of electrochemical EPR methods is best illustrated by citing a few specific examples from the extensive literature. More complete compilations appear in the reviews listed in Appendix I, but the studies mentioned next provide some appreciation for the techniques. 

Some reductions that are not possible with triethylsilane and trifluoreacetic acid (5, 695 6, 616) can be effected with triethylsilane and boron trifluoride hydrate. Although benzene, naphthalene, and phenanthrene are not reduced, anthracene and naphthacene are reduced to tetrahydro derivatives in high yield. 1- or 2-Hydroxynaphthalene is reduced to tetralin in moderate yield. ... 

A reduced anthracene complex has been prepared by reaction of TiCL dmpe) (dmpe= l,2-bis(dimethyl)phos-phinoethane 9 with NajCuHio], furnishing 10 (Scheme 2).8 The reaction of Cp TiCl3 11 with anthracenium anion results in the formation of compound 12 where one arene is -coordinated while the other adopts if hapticity. Reaction of the anthracene complexes with CO induces formation of the known carbonyl complexes, Ti(CO)3(dmpe)9 and [Cp Ti(CO)3], respectively.10... 

Anthracene has also been crystd from EtOH, chromatographed through alumina in hot benzene (fume hood) and then vac sublimed in a pyrex tube that has been cleaned and baked at 100°. (For further details see Craig and Rajikan J Chem Soc, Faraday Trans 1 74 292 1978 and Williams and Zboinski J Chem Soc, Faraday Trans 1 74 611 1978.) It has been chromatographed on alumina, recrystd from n-hexane and sublimed under reduced pressure. [Saltiel J Am Chem Soc 108 2674 1986 Masnori et al. J Am Chem Soc 108 1126 1986.] Alternatively, it was recrystd from cyclohexane, chromatographed on alumina with n-hexane as eluent, and recrystd two more times [Saltiel et al. J Am Chem Soc 109 1209 1987]. 

To demonstrate the effect in more detail a series of experiments was carried out similar to that of volume overload, but in this case, the sample mass was increased in small increments. The retention distance of the front and the back of each peak was measured at the nominal points of inflection (0.6065 of the peak height) and the curves relating the retention data produced to the mass of sample added are shown in Figure 7. In Figure 7 the change in retention time with sample load is more obvious the maximum effect was to reduce the retention time of anthracene and the minimum effect was to the overloaded solute itself, benzene. Despite the reduction in retention time, the band width of anthracene is still little effected by the overloaded benzene. There is, however, a significant increase in the width of the naphthalene peak which... 

Unlike henzoquinone, it is not reduced by sulphur dioxide (see Prep. 85, p. 193). Heated with HI 01 zinc dust it is converted into anthracene. 

A solution of 10 g of 9 10-dihydro-9 10-ethano-(1 2)-anthracene-(9)aldehyde (made from anthracene and acrolein) and 10 g of monomethylamine in 100 cc of ethanol is heated at 80°C for 4 hours in an autoclave. The reaction mixture is then evaporated to dryness under reduced pressure to leave a crystalline residue which is dissolved in 150 cc of ethanol and, after the addition of 2 g of Raney nickel, hydrogenated at 40°C under atmospheric pressure. When the absorption of hydrogen has subsided, the catalyst is filtered off and the filtrate evaporated under reduced pressure. An oil remains which is covered with 100 cc of 2N hydrochloric acid. The 9-methylamino-methyI-9 10-dihydro-9 10-ethano-(9 10)-anthracene hydrochloride crystallizes immediately after crystallization from methanol it melts at 320°-322°C. 

Thus, 9,10-diphenylanthracene ( p = — 1.83 V vs. SCE) is reduced at too positive a potential and hence its rate of reaction with the sulphonyl moieties is too low. On the other hand, pyrene (Ep = — 2.04 V) has a too negative reduction potential and exchanges electrons rapidly both with allylic and unactivated benzenesulphonyl moieties. Finally, anthracene Ev = —1.92 V) appears to be a suitable choice, as illustrated in Figure 3 (curves a-d). Using increasing concentrations of the disulphone 17b, the second reduction peak of XRY behaves normally and gives no indication of a fast electron transfer from A. 

Another interesting scavenger is polymer-supported anthracene, developed by Porco for the scavenging of dienophiles [109]. An example of its application to the synthesis of a complex 5,8-dihydro-(l,2,4)triazolo[l,2-a]pyridazine-l,3-diones via hetero-Diels-Alder reaction followed by removal of the excess of triazole-3,5-dione under microwave irradiation is depicted in Scheme 24. For this particular example, moving from thermal heating (toluene, 100 °C) to a microwave-assisted protocol (DCE, 150 °C) reduced scavenging time from 3 h to just 15 min. 

The addition of a rhamnolipid biosurfactant produced by Pseudomonas aeruginosa stain ATIO apparently reduced the extent of degradation by endogenous bacteria of benz[fl]anthracene and chrysene in a creosote-contaminated soil (Vinas et al. 2005). 

Anthracenes are planar by virtue of the necessity of maintaining aromaticity. When the central ring is reduced, an overall "butterfly" conformation is achieved. For reasons that are not yet understood at the molecular level, this conformation is often associated with central antidepressant activity. 

Model Component Studies. Model compound work with this system showed that anthracene was reduced to its 9,10-dihydro derivative (35% yield). Bibenzyl, on the other hand, was recovered unchanged, with only a trace of toluene observed. 

Another recent application to the activation of transition metals was reported (247) by Bonnemann, Bogdavovic, and co-workers, in which an extremely reactive Mg species was used to reduce metal salts in the presence of cyclopentadiene, 1,5-cyclo-octadiene, and other ligands to form their metal complexes. The reactive Mg species, characterized as Mg(THF)3 (anthracene), was produced from Mg powder in THF solutions containing a catalytic amount of anthracene by use of an ultrasonic cleaning bath. A plausible scheme for this reaction has been suggested ... 

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