Phenanthrene ring

The intramolecular photochemistry of 9-[2-(7V-substituted aminomethyl)-l-naph-thyl]phenanthrenes has also been studied101 (equation 40). The pyrroline derivatives are obtained by the addition of the N—H to the C-9 carbon atom of phenanthrene ring. Reasonable yields for the highly regioselective products are obtained by irradiation in benzene solution. 

Aromatics, hydrocarbons containing one or more aromatic nuclei, such as benzene, naphthalene, or phenanthrene ring systems, that may be linked up with (substituted) naphthalene rings and/or paraffinic side chains. 

Several tetra- and pentacyclic systems were prepared from Pro, which was first -substituted with naphthalene or phenanthrene rings whereupon the cyclization took place. Such reactions were used for synthetic ap-proaehes toward alkaloids vinceten from Cynachum vincetoxicum (the tetrahydrobenzo /]pyrrolo[l,2-Z ]isoquinoline system 146) (79LA1212 84AJC819) or tylophorine (65T2573). 

Noscapine [128-62-1] (45) is the second most abundant alkaloid found in opium. Unlike most opium alkaloids, however, it has an isoquinoline rather than a phenanthrene ring system. Noscapine was first isolated in 1817 but its antitussive activity was not demonstrated pharmacologically until 1952 (63). Clinical studies have confirmed its effectiveness. It is not a narcotic and has a wide margin of safety when given orally. Death could be produced in rats only with doses > 800 mg/kg (64). Noscapine is isolated from the water-insoluble residue remaining after processing opium for the manufacture of morphine. 

A further confirmation of the metal carbene mechanism is provided by enyne intramolecular metathesis reactions such as that depicted in equation 61. The C=C bond in the substrate becomes the single bond attaching the alkenyl group to the phenanthrene ring system634,635. 

Intermolecular (2ir + 2ir) photocycloaddition to the 9,10-position of the phenanthrene ring has been extensively studied in the last three decades. Unsubstituted phenanthrene reacts with electron-poor olefins such as dichloroethene,... 

However, Kubo et al. found the unusual (3 + 2) intermolecular photocycloaddition of alkenes to the naphthalene ring at the 1,8-position. The same group also reported the (3 + 2) photocycloaddition of alkenes to phenanthrene ring at the 8,9-position. 

Photoreactions of 9,10-dicyanophenanthrene with 1,3-butadiene gave a novel (3 + 2) photocycloadduct at the 1,10-position of the phenanthrene ring (403) to one double bond of 1,3-butadiene and a (2 + 2) cycloadducts at the 9,10-position (404,405) [366] (Scheme 108). Compound 403 was formed from the singlet excited state of 9,10-dicyanophenanthrene, and 404-405 were from triplet state of 9,10-dicyanophenanthrene. This is the first example of the (3 + 2) photocycloaddition to the phenanthrene ring. 

The chemical structure of vitamin D3 is closely related to its precursor, 7-dehydrocholesterol, from which it is produced by a photochemical reaction. Therefore, vitamin Do is closely related structurally to the four-ring nucleus of steroids derived from the cyclopentanoperhydro-phenanthrene ring system. No vitamin D activity is noticed until the B ring of 7-dehydrocholesterol is opened between C-9 and C-10. Thus, vitamin D3 is a 9,10-seco steroid and its carbon skeleton is numbered accordingly (Scheme I). The important aspects of its chemistry center about the 5,6,7-cis-triene structure. The formula for vitamin D3 is C27H44O and its formula weight is 384.64. 

The metabolism of cholesterol involves modifications to the alkyl side chain and the introduction of substituents onto the phenanthrene ring. A group of enzymes, monooxygenases, plays an important role in catalyzing the formation of bile salts in the liver and steroid hormones in the adrenal gland... 

The conversion of cholesterol to bile salts begins when hydroxyl groups are introduced into the phenanthrene ring of cholesterol by the action of cholesterol 7-a-hydroxylase, followed by modification of the side chain. Cholic acid and chenodeoxycholic acid are produced, as shown in Fig. 13-24. 

If the statistical parameters obtained upon solution of the matrix indicate that the additivity assumption is valid, the de novo constants can then be used to predict the activity of (a) those compounds used in derivation of the constants and (b) all possible combinations of the various groups at each position. This is not much of a saving when one has only two or three positions of a molecule which can be substituted, but in more complex situations this can be a powerful tool. An example is given below, where six different positions of the phenanthrene ring were substituted with three, three, six, three, six, and three substituents, respectively ... 

The data on isopropyl group transfer in Table I show that the secondary aliphatic-aromatic carbon-carbon bond is very reactive when the aliphatic group is linked to either a phenolic ring or a phenanthrene ring. The reaction is very slow when the isopropyl group is linked to a nonactivated benzene ring. The relative reactivities of the secondary carbon bond in the first two structures could not be evaluated because the isopropyl group transfer went to completion in the case of o-iso-... 

The numbering of the phenanthrene ring in the following alkaloids is according to accepted practice [1,102-106], and is illustrated in the structure of northalicthuberine (63). 

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