Phenanthrene partial hydrogenation

The partially hydrogenated phenanthrene derivative 18 (entry 4) is a very moderate diene due to the steric crowding caused by the substituents and the anulated rings, and it reacts even with highly reactive dienophiles such as maleic anhydride (MA) or N-phenylmaleic imide only at high pressure. The minor product 20 in the reaction with MA obviously stems from diene 21. This can be explained by a double-bond isomerization 18 - 21 prior to the cycloaddition, certainly catalyzed by traces of acid present in the MA. In the absence of acid only the Diels-Alder adduct 22 derived from diene 18 was observed. In the reaction of diene 23 with MA (entry 5) a similar sequence of steps was observed. A [1,5] shift of the C—O bond in 23, again certainly acid-catalyzed, produces the diene 26 followed by the Diels-Alder reaction with MA to give 24 and 25. 

Anthracene and phenanthrene are converted to their 9,10-dihydro derivatives in high yield. Other partially hydrogenated intermediates formed by further stepwise hydrogen addition can also be isolated under suitable experimental conditions.10 18 Platinum and palladium exhibit different selectivities in the partial hydrogenation of polycyclic aromatics under mild conditions 108... 

Partial hydrogenation of polycyclic aromatics can also be accomplished with [Co(CO)4]2 under hydroformylation conditions.24,26 Isolated benzene rings are generally resistant under these conditions. Polycyclic aromatics, consequently, are only partially hydrogenated174 [Eq. (11.38)], and highly condensed systems usually form phenanthrene derivatives ... 

A route to partially hydrogenated phenanthrenes relies on the Diels-Alder reaction of a benzyne to an annulated furan, e.g. (501) - (503) (Scheme 117). However, regiochemistry raises its ugly head when both the furan and the benzyne are nonsymmetrically substituted (Scheme 118). Hence, the [4 + 2] cycloaddition of 3-methylbenzyne with 2>substituted furans (504) gave the anti and syn adducts (506)... 

The initial rate of hydrogenation of fused polycyclic aromatics increases with the number of rings present phenanthrene > naphthalene > benzene. Only one ring is generally saturated at a time. This partial hydrogenation is accomplished because... 

The regioselectivity of the partial hydrogenation of polycyclic aromatics depends on both the substrate structure and the catalyst used. The hydrogenation of phenanthrene, (28) over Raney nickel or palladium takes place by way of the initial formation of the 9,10 dihydro species, 29 (Eqn. 17.27). 

A similar reaction occurs when morphine methiodide [16] and thebaine methiodide [17] are heated with acetic anhydride, a process usually called acetolysis, and phenanthrene itself is obtained in low yield by the distillation of morphine with zinc dust [18]. These reactions and the empirical formula for codeine led to the conclusion that in the latter one NMe group and two carbon atoms were in some way attached to a partially hydrogenated phenanthrene skeleton. 

Acetylthebaol [i, R = Ac] can be oxidized to a quinone [n] without loss of groups, showing that the 9 10 positions are free from substituents [07-68], and methylthebaol [i, R = Me] [72] was shown to be identical with 3 4 6-trimethoxyphenanthrene by synthesis of the latter [73]. In this way the positions of the oxygen functions in thebaine were established and the base identified as a derivative of a partially hydrogenated phenanthrene. 

A route to partially hydrogenated phenanthrenes relies on the Diels-Alder reaction of a benzyne to an annulated furan, e.g. (501) (503) (Scheme 117). However, regiochemistry raises its ugly head ... 

This new zeolite-catalyzed ring-shift isomerization could provide a new route to anthracene and its derivatives [Song, 1996], which are valuable chemicals in demand, from phenanthrene, which is rich in liquids from coal. Selective partial hydrogenation of phenanthrene would be needed as the first step. Possible applications of sym-OHAn include the manufacturing of anthracene (for dyestuffs and fine chemicals), anthraquinone (pulping agent), and pyromellitic dianhydride (the monomer for polyimides such as Du Pont s Kapton) [Song and Schol rt, 1993]. Fundamental research is needed to clarify the mechanisms and reaction pathways. 

Hypervalent iodine species were demonstrated to have a pronounced catalytic effect on the metalloporphyrin-mediated oxygenations of aromatic hydrocarbons [93]. In particular, the oxidation of anthracene (114) to anthraquinone (115) with Oxone readily occurs at room temperature in aqueous acetonitrile in the presence of 5-20 mol% of iodobenzene and 5 mol% of a water-soluble iron(llI)-porphyrin complex (116) (Scheme 4.57) [93]. 2-ferf-Butylanthracene and phenanthrene also can be oxygenated under similar conditions in the presence of 50 mol% of iodobenzene. The oxidation of styrene in the presence of 20 mol% of iodobenzene leads to a mixture of products of epoxidation and cleavage of the double bond. Partially hydrogenated aromatic hydrocarbons (e.g., 9,10-dihydroanthracene, 1,2,3,4-tetrahydronaphthalene... 

Partial hydrogenation. A soln. of phenanthrene in 1 1 butylamine-benzene hydrogenated at 120°/100 psi with Na,Rb prepared in situ from Na and Rb-carbonate... 

It is also possible for the two olefinic units of the diene to be in two different alicyclic rings. As shown below, l,T-bicyclohexenyl 32 gives the product with a partially hydrogenated phenanthrene nucleus 33. ... 

Phenanthrene is converted to partially and totally reduced phenanthrene by catalytic hydrogenation [415, 416, 417], Partial reduction to 1,2,3,4-tetra-hydrophenanthrene can also be achieved by sodium [418. ... 

In the USA, this plan was directed from 1929-1939 by the Committee on Drug Addiction of the National Research Council (NRC) with financial support from the Rockefeller Foundation. The program consisted of modification of the morphine molecule at all accessible points and also targeted (modified) partial structures of the morphine molecule, such as phenanthrene, hydrogenated phenanthrene, isoquinoline, dibenzofuran, and carbazole. More than 150 derivatives of morphine and more than 300... 

Milton Denekas Isn t the solubility of coal in phenanthrene a function of temperature of extraction, and therefore a partial thermal cracking process Isn t this reaction somewhat different from the action of tetralin on coals since the latter solvent has hydrogen available for hydrogenation ... 

The direct synthesis of anthraquinone from phthalic anhydride and benzene has been reported to proceed over zeolite Beta [50] in a shape selective manner. In a conventional anthraquinone synthesis, anthracene is used as a feedstock for oxidation. Once there is a shortage of it in the market, additional anthracene could be produced by isomerization of its isomer, viz. phenanthrene. This, however, is not possible by direct isomerization of the trinuclear aromatic system but involves the partially (symmetrically) hydrogenated species. Consequently, isomerization of symmetrical octahydrophenanthrene to symmetrical octahydro-anthracene was studied by Song and Moffatt [51]. As sketched in Figure 3, a high yield of symmetrical octahydroanthracene can be obtained over zeolite H-mordenite (ngj/nyy = 8) at 250 °C (liquid phase, decalin as solvent). These examples show that (shape selective) catalysis on zeolites is more and more expanding into the conversion of polycyclic aromatics, and we foresee continued interest and success in this field of zeolite catalysis. 

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. ... 

With polycyclic aromatic compounds, it is often possible, by varying the conditions, to obtain either partially or completely reduced products. Naphthalene can be converted into the tetrahydro or decahydro compound over Raney nickel depending on the temperature. With anthracene and phenanthrene, the 9,10-dihydro compounds are obtained by hydrogenation over copper chromite although, in general,... 

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