Benzo phenanthrene 5,6-oxide

This section is dedicated to arene oxides of bicyclic and tricyclic arenes (e.g., naphthalene, anthracene, and phenanthrene oxides), whereas higher arenes and particularly benzo[a]pyrene (one of the most toxic and intensively investigated PAHs) are examined in Sect. 10.4.4. 

Comparison of the reactivities of benzene oxides, naphthalene oxides, phenanthrene oxides, and arene oxides derived from benzo [a] pyrene and 7,12-dimethylbenz[a] anthracene with hepatic glutathione S-epoxide transferase showed that benzene oxides without electron-withdrawing groups are poor substrates as also are polycyclic arene oxides. Only naphthalene oxide was a good substrate. 

Laarhoven has examined the fate of the dihydrophenanthrene intermediate (148) formed by photocyclisation of the styryl benzo-phenanthrenes (149). When the reaction is performed in the presence of iodine as oxidant the expected arene (150) is obtained but in the absence of the oxidant compound (148) rearranges to the more stable, isolable dlhydroarenes (151) and (152). This rearrangement is base catalysed and the proportions of (151) and (152) isolated depend upon the nature of the base and the solvent. 

Besides a parent ion, the mass spectra of benzo- and dibenzothiepins show the corresponding naphthalene or phenanthrene radical cations as the base peak.2-16 The mass spectra of 1-benzo-thiepin 1-oxides and 1,1-dioxides show the same naphthalene radical cation, formed by loss of sulfur monoxide or sulfur dioxide, respectively.14 In contrast, in the mass spectrum of 2,7-di-terf-butylthiepin peaks resulting from the loss of sulfur are not found.17... 

Hemoglobin is another heme-containing protein, which has been shown to be active towards PAH, oxidation in presence of peroxide [420], This protein was also modified via PEG and methyl esterification to obtain a more hydrophobic protein with altered activity and substrate specificity. The modified protein had four times the catalytic efficiency than that of the unmodified protein for pyrene oxidation. Several PAHs were also oxidized including acenaphthene, anthracene, azulene, benzo(a)pyrene, fluoranthene, fluorene, and phenanthrene however, no reaction was observed with chrysene and biphenyl. Modification of hemoglobin with p-nitrophenol and p-aminophenol has also been reported [425], The modification was reported to enhance the substrate affinity up to 30 times. Additionally, the solvent concentration at which the enzyme showed maximum activity was also higher. Both the effects were attributed to the increase in hydrophobicity of the active site. 

Methods for the synthesis of the biologically active dihydrodiol and diol epoxide metabolites of both carcinogenic and noncarcinogenic polycyclic aromatic hydrocarbons are reviewed. Four general synthetic routes to the trans-dihydrodiol precursors of the bay region anti and syn diol epoxide derivatives have been developed. Syntheses of the oxidized metabolites of the following hydrocarbons via these methods are described benzo(a)pyrene, benz(a)anthracene, benzo-(e)pyrene, dibenz(a,h)anthracene, triphenylene, phen-anthrene, anthracene, chrysene, benzo(c)phenanthrene, dibenzo(a,i)pyrene, dibenzo(a,h)pyrene, 7-methyl-benz(a)anthracene, 7,12-dimethylbenz(a)anthracene, 3-methylcholanthrene, 5-methylchrysene, fluoranthene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)-fluoranthene, and dibenzo(a,e)fluoranthene. 

The EH-catalyzed hydration of the enantiomers of the K-region epoxides of BaA, CR, and BcPh allows informative comparisons to be made [92 - 94], With four among the six substrates, nucleophilic attack is selective for the oxirane C-atom with (5)-configuration (Fig. 10.12). This is, for example, true for the two enantiomers of chrysene 5,6-oxide. Looking at the data in another way, it is also apparent that, irrespective of the enantiomer, nucleophilic attack occurs preferentially at C(5) for benz[a]anthracene 5,6-oxide, but at C(6) for benzo[c]phenanthrene 5,6-oxide. In other words, the regio- and... 

Both procaryotic and eukaryotic microorganisms have the enzymatic potential to oxidize aromatic hydrocarbons that range in size from a single ring (e.g., benzene, toluene and xylene) to polycyclic aromatics (PC As), such as naphthalane, anthracene, phenanthrene, benzo [a] pyrene and benz [a] anthracene (Table 4.4). However, the molecular mechanisms by which bacteria and higher microorganisms degrade aromatic compounds are fundamentally different. 

The cyclization of trans- 1,2-glycols can also be brought about, using p-toluenesulfonyl chloride and sodium hydride. Benzo[c]phenanthrene 5,6-oxide (31) has been prepared in 8% yield from the corresponding trans-glycol (32).2 3... 

In cases where the oxirane ring is unsymmetrically substituted, the product structure can be predicted on the basis of attack at the most electrophilic center. This center has the lowest Dewar reactivity number (A/,) as predicted by MO calculations. The following example is illustrative. Benzo[c]phenanthrene 5,6-oxide (31) could give rise to two different zwit-terions (237 and 238). The former has a Dewar reactivity number 1.79 and the... 

Bernstein et al. have used IR spectroscopy and mass spectrometry to study the products formed from photochemical transformation of naphthalene, anthracene, chrysene, phenanthrene, pyrene, tetracene, pentacene, perylene, benzo(e)pyrene, benzo(ghi)perylene, and coronene in water ices using ultraviolet radiation under astrophysical conditions [27]. The results of their investigation have revealed that peripheral carbon atoms can be oxidized to produce aromatic alcohols, ketones, ethers (when bay region is present,... 

A number of K-region arene oxides have been detected as intermediates in the metabolism of the corresponding PAHs in liver systems for example, phenanthrene, benz[a]anthracene, pyrene, benzo [a]pyrene, and dibenz(a,h)anthracene. These K-region arene-oxide metabolites were generally only detected by trapping the radiolabeled intermediate. The arene-oxide metabolite 102 obtained from a-naphthoflavone was found to be sufficiently stable with respect to isomerization and resistant to attack by epoxide hydrolase so that it could be isolated and identified spectroscopically. ... 

R-configured carbon atom vide supra), microsomal epoxide hydrolase attacks at R- as well as S-configuxed carbon atoms. With some arene oxides, both enantiomers are attacked at the same carbon, irrespective of configuration (e.g., benzo[c]phenanthrene). Other arene oxides (e.g., benzo[a]-pyrene 4,5-oxide) undergo the primary reaction, predominantly at S-con-figured carbon (Yang, 1988). 

Treatment of ketone 409 with lithium diisopropylamide (LDA) results in the ethyl 1,2-dihydroxybenzoate 410 in a 74% yield (equation 191) . The acid-catalyzed isomerization of diarene oxides derived from benz[a]anthracene, chrysene and benzo[c]phenanthrene gives mixtures of isomeric polycyclic phenols. Finally, it should be mentioned that dibenzo[i>, ]oxepin 411 undergoes an interesting rearrangement to 2-hydroxyphenylindene 412 (equation 192). 

The reaction of benzo[f]quinoline with methylsulphinyl carbanion prepared from dimetl lsulphoxide and sodium hydride leads to the 5-methyl and the 6-methyl derivatives in a 1 4 ratio. Although benzo[flquinoline-4-oxide gives a high yield of phenanthrene under these conditions, the carbanion generated using potassium t-butoxide as the base leads to alkylation at C-3 and to simultaneous deoxygenation (Y. Hamada and I. Takeuchi. J. org. Chem.. 1977. fa, 4209). 

Some PAHs are degraded by oxidation reactions that have been measured in the dark (to eliminate the possibility of photodegradation). Korfmacher et al. (1980) found that, while fluorene was completely oxidized, fluoranthene and phenanthrene were not oxidized, and benzo[a]pyrene and anthracene underwent minimal oxidation. These compounds were tested adsorbed to coal fly ash the authors stated that the form of the compound (adsorbed or pure) and the nature of the adsorbent greatly affected the rate and extent of oxidation. 

The ultraviolet spectrum of benzo[c]cinnoline in -hexane shows four band systems centred at approximately 250, 300, 350, and 400 nm. The first three of these are n-n bands, corresponding to those in the spectrum of phenanthrene, while the long-wavelength band, of low intensity, is due to an n-7T transition. In hydroxylic solvents this last band moves to shorter wavelengths and becomes obscured. Substituent effects, and those due to protonation and to A-oxidation, have been discussed in a series of papers by Holt and co-workers. ... 

Ozonation of benzo[r,s,t]pentaphene (7) followed by oxidative workup led to benzo[r,s,t]pentaphene-5,8-dione (12) (14%), phthalic acid (13) (4%), p-terphenyl-2,2, 3, 2"-tetra-carboxylic acid-2, 3 -anhydride (14) (10%), and 2-(o-car-boxyphenyl)- ,10-phenanthrenedicarboxylic acid anhydride (15) (3%), with a 56% recovery of unreacted 7, Ozonation of pentaphene (11) led to a peroxidic mixture which on oxidative workup led to 2,2 -binaphthyl-3,3 -dicarboxalde-hyde (16) (16%), 2,2 -binaphthyl-3,3 -dicarboxylic acid (17) (16%), and 13 (2%), with a 28% recovery of unreacted 11. A comparison of the reactivity to ozone of carcinogenic polycyclic aromatics benzo c]phenanthrene (1), 7,12-di-methylbenz [a] anthracene (2), 3-methylcholanthrene (3), dibenz[si,]] - (4), and dibenzlsi, ]anthracene (5), benzo Si -pyrene (6) and 7, and the noncarcinogen 11, all determined in our laboratory, leads us to conclude that there is no simple, consistent correlation between carcinogenicity, K-and L-region additivity towards ozone and the Pullmans electronic theory of carcinogenesis. 

The past year has seen the publication of Comprehensive Organic Chemistry, one volume of which contains much information on the six-membered ring systems to be reviewed in this article a monograph on the chemistry of condensed pyrazines has also appeared. Reviews on 1,4-thiazines, l,3-benzothiazines," pyridazines, benzo[c]cinnolines, quinazolines, purines, pyrrolo[3,2-c]quino-lines, 1,10-phenanthroline and its complexes, polyaza-phenanthrenes, and 1,9- and 1,10-diaza-anthracenes have been published. Other specialist reviews are devoted to catalytic methods of obtaining pyridine bases pyridine N-oxides the stereochemistry of quinolizines, indolizines, and pyrrolizines benzothiazinone dioxides 2-quinazolones and their cyclic homologues (e.g. 

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