Dihydrophenanthrene, from phenanthrene

Normally, esters beta to a radical are perfectly stable and do not furnish olefins and carboxyl radicals.6 This is true even for 1 where tin hydride reduction affords only 2. Clearly, conjugation with two phenyls is not a sufficient driving force for elimination. However, the driving force in the change from dihydrophenanthrene to phenanthrene would be greater and in... 

A number of dihydrophenanthrenes and phenanthrenes possess antifungal activity and are important as phytoalexins. Although many of these and related compounds are derived from pathways discussed in this chapter, others that coincidentally possess phenanthrene structures are derived from isoflavonoid precursors and are discussed under that topic. 

Dimethylaniline/irradiation 9,10-Dihydrophenanthrene-9-carboxylic acids from phenanthrenes... 

These results show that reduction of the multiple bonds takes place through trans-addition. By reduction of diphenylacetylene in dimethylformamide in the presence of carbon dioxide Wawzonek and Wearring [103] obtained diphenylfumaric acid, diphenylmaleic anhydride and meso-diphenylsuccinic acid in the proportions 2,5 1 7. If it is assumed that the meso acid is formed from fumaric acid, these results demonstrate the stereospecificity of the process, contrary to the assertions made by Wawzonek and Wearring [103], From phenanthrene in the presence of carbon dioxide they obtained trans- 9,10-dihydrophenanthrene-9,10-dicarboxylic acid. 

Bezalel et al. (1996) reported that the white rot fungus Pleurotus ostreatus, grown in basidiomycetes rich medium, metabolized 94% of the phenanthrene added. Approximately 52% was converted to /rans-9,10-dihydroxy-9,10-dihydrophenanthrene (28%), 2,2 -diphenic acid (17%), and unidentified metabolites (17%). In addition, 3% was mineralized to carlaon dioxide. Sack et al. (1997) reported that phenanthrene was degraded by an Aspergillus niger sixain isolated from a mineral oil-contaminated soil in La Plata, Argentina. The major metabolite was identified via GC/MS as 1-methoxyphenanthrene. Two minor metabolites identified were 1- and 2-phenanthrol. 

Isolation of Oxidation Products. After oxygen absorption had ceased, or reached the desired value, the oxidates were poured into water. In many cases the reaction product could be removed by filtration in high yield. In this manner xanthone (m.p. 172-174°C.), was isolated from oxidations of xanthene or xanthen-9-ol thioxanthone (m.p. 208-210°C.), from thioxanthene acridine (m.p. 107-109°C.), from acridan anthracene (m.p. 216-217°C.), from 9,10-dihydroanthracene phenanthrene (m.p. 95-99°C.), from 9,10-dihydrophenanthrene pyrene (m.p. 151-152.5°C.) (recrystallized from benzene) from 1,2-dihydropyrene and 4-phenan-throic acid (m.p. 169-171 °C.) (recrystallized from ethanol) by chloroform extraction of the hydrolyzed and acidified oxidate of 4,5-methyl-enephenanthrene. 

The submitter used a 65-cm. Podbielniak type column equipped with partial reflux head.6 For distillation of the sodium-treated phenanthrene the checkers employed a 6-in. Vigreux column. For the fractionation of the dihydrophenanthrene, the checkers employed a 15-cm. spinning-band column obtainable from Nester and Faust, Exton, Pennsylvania. 

Dihydrophenanthrene has been prepared from 2,2 -bis(bromomethyl)biphenyl and sodium 8 from the reduction of 2,2 -diiodobibenzy 1 in the presence of 1% palladium on barium carbonate catalyst 8 by the hydrogenation of phenanthrene in the presence of nickel8 or copper-chromium oxide catalyst 10 and by the coupling of 2,2 -bis(bromomethyl)biphenyl with lithium phenyl.11... 

Stilbenes and associated molecules provide very good examples of the formation of intermediate unstable isomers which give a chemical route for internal conversion. Upon irradiation, stilbenes undergo a cis-trans isomerization as the predominant reaction. However, under oxidative conditions phenanthrene is also formed.12 It was shown that the phenanthrene came only from c/s-stilbene (13),61 and that an intermediate unstable isomer, nms-dihydrophenanthrene (14), was the precursor of the phenanthrene.62-64 The dihydrophenarithrene was in its ground state, but vibrationally excited, and was formed by a process calculated to be endothermic by 33 10 kcal/mole-1.02 Oxygen or other oxidants converted it to phenanthrene (15), but in the absence of oxidants it was either collisionally stabilized or reverted to m-stilbene. 

We know that C6-cyclization of 1-(naphthyl-2)-butene is possible without metal catalysts. The products are dihydrophenanthrene over quartz and 1,2,3,4-tetrahydrophenanthrene plus phenanthrene over alumina (50). The latter apparently catalyzes the redistribution of hydrogen in dihydrophenanthrene. Neither anthracene nor dihydro- or tetrahydroanthracene are formed over quartz or alumina from 1-(naphthyl-2)-butene. Plate and Erivanskaya concluded from this that the 2-alkylnaphthalene - anthracene reaction does not involve naphthylbutene intermediate (27). 

Cis-stilbenes, which are easily obtained from their trans-isomers by trans, cis-photo-isomerization, can give rise to dihydrophenanthrene derivatives upon direct irradiation (Scheme 9.17). The latter compounds are easily converted into phenanthrenes under oxidizing conditions (oxygen, I2, or rc-electron acceptors such as tetracyano-ethene) [24]. 

Three novel phenanthrenes have been isolated from the wetland plant Juncus acutus. The structures of the novel phenanthrenes were established as 2-hydroxy-l,6-dimethyl-5-vinyl-phenanthrene (320), 2,7-dimethoxy-l,6-dimethyl-5-vinylphenanthrene (321) and 2-hydroxy-6-hydroxymethyl-l-methyl-5-vinyl-phenanthrene (322) [164, 165]. In spite of the great number of 9,10-dihydrophenanthrenes, only quite a small number of phenanthrenes have been reported until now as constituents of Juncaceae. 

By contrast to the thermal process, the photochemistry of 2-vinylbiphenyl (249) and 4-vinylphenan-threne (250) has been widely used in connection with syntheses of polycyclic aromatic compounds, complementing the most commonly used stilbene to phenanthrene transfoimation. ° For example, the product obtained from the conrotatory photocyclization of 2-(a-styryl)biphenyl (252) can be trapped by an oxidant to give the phenanthrene (254) or suffers a 1,S-H shift to give the dihydrophenanthrene... 

The frazzs-4a,4 -dihydrophenanthrene (lb) intermediates have to be removed from the equilibrium by aromatization to the corresponding phenanthrenes (e. g. 2) either by cleavage of a suitable leaving group at the 4 a-position in 1 b or, most commonly, by an oxidation agent the generally accepted method employs the use of air plus a catalytic amount of iodine. This procedure has been applied as a key step in numerous syntheses of interesting PAHs, such as helicenes [70] as well as the first syntheses of [7]phenacene (34, [71]) and [7]circulene (17, [72]) respectively (see Scheme 5,13). 

The exciplexes formed between arenes and good acceptors such as dicyanobenzene can dissociate to radical ion pairs if the solvent used is sufficiently polar. The radical cation of the arene is then susceptible to attack by nucleophiles and this can lead to products of addition or substitution of the arene. A preliminary account of how salts such as tetrabutylammonium tetrafluoroborate can serve to mediate the charge separation in less polar solvents was reported last year. A second paper from the same group has now been published which describes the formation of the amino substituted dihydrophenanthrene (86) during the irradiation of a solution of phenanthrene, dicyanobenzene and propylamine in relatively non-polar solvents such as THF in the presence of tetrabutylammonium tetrafluoroborate. In the absence of the salt no product is formed. 

If an ortho substituent is present in a stilbene it can direct the regiochemistry of the photocyclisation towards or away from the position of the substituent. In addition, it can act as a potential leaving group, obviating a need for an oxidant to generate a phenanthrene from the dihydrophenanthrene Intermediate. Thus, for... 

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