Hydrophenanthrenes, structural

Sym-octahydrophenanthrene (HgPh) would be expected to follow the same rearrangement-dehydrogenation reactions as Tetralin, except with more isomer and product possibilities. The reactions shown in Figure 1 illustrate the many structures expected from sym-HgPh in the presence of free radical acceptors. Unlike Tetralin, hydrophenanthrenes have multiple structures which each, in turn, form various isomers. The amounts of these isomers are dependent upon the type of hydrogen-transfer reactions and the environment of the system. 

Composition. Rosin is primarily a complex mixture of monocarboxylic acids of alkylated hydrophenanthrene nuclei. These constituents, known as resin acids, represent about 90% of rosin. The resin acids are subdivided into two types, based on their skeletal structure. The abietic-type acids contain an isopropyl group pendent from the carbon numbered 13. The pimaric-type acids have a methyl and vinyl group pendent from the same carbon atom. Figure 1 shows the structure of typical resin acids abietic acid, C20H30O2 (1) is predominant. The remaining 10% of commercial rosin consists of neutral materials that are either hydrocarbons or saponifiable esters. These materials are derived from resin acids by decarboxylation or esterification. 

Similar results were obtained with a structurally related hydrophenanthrene system119. 

The clositig of a six-membered ring by this process is possible when favored by structural rigidity of the molecule as in the preparation of 9,10 hydrophenanthrene from phenyllithium and 2,2 -di-(bromomethyl)-biphenyl. ... 

The mechanism in Scheme 19 is somewhat speculative, and relies heavily on the assumption that axial attack of solvent is more energetically favorable than equatorial attack of solvent on carbocations similar in structure to 64. However, the stereochemistry of acid-catalyzed hydrolysis of two diastereomeric hexa-hydrophenanthrene 9,10-epoxides (65 and 67) provides support for this proposal. These two epoxides contain transfused cyclohexane moieties that restrict the geometry of each epoxide to a single conformation. Reaction of 65 with H+ yields a single carbocation conformation 66, in which the hydroxyl group is forced to occupy an axial position (Scheme 20). 

Sinomenine is the main alkaloid of the roots and stems of Sinomenium acutum Rehder and Wilson and Sinomenium diversifolius Diels, climbing plants indigenous to the woods of southern Japan (89). Sinomenine contains a hydrophenanthrene nucleus and an ethanamine bridge and is structurally very similar to morphine and codeine. The configuration at the asymmetric centers, C-5, C-9, C-12, and C-14 is the mirror image of those in morphine it affords a route to interesting enantiomorphs of morphins and morphinone derivatives. 

The rosin moiety of the polymer, polyesterimides and polyamidei-mides alike, offers interesting possibilities which may be explored further. One such possibility is the utilization of the residual unsaturation in the hydrophenanthrene ring structure of the rosin moiety. Although this unsaturation site is sterically very much hindered and therefore stable, attempts may be made to exploit it for crosslinking or other reactions by free radical processes. If this is successful, rosin polymers may be used for fabrication of void-free high temperature laminates and composites with suitable formulation. 

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