Phenanthrene, structure

Isocyanates 345 react with phenanthrenequinone 346 and triphenylarsine oxide to give photochromic oxazines 347 (Equation 48) <1993PS(81)37>. The isocyanate can be replaced by a phosphinimine and the phenanthrene structure can also be replaced by the corresponding phenanthroline (Equation 49) <2003WO42195>. The /ra r-fused tetrahydrooxazine 349 was prepared from epoxide 348 and 2-aminoethyl sulfate (ethanolamine 0-sulfonic acid) (Equation 50) <1987AP625>. 

The most abundant aromatics in the mid-distillate fractions are di- and trimethyl naphthalenes. Other one and two ring aromatics are undoubtedly present in small quantities as either naphtheno- or alkyl-homologues in the Cn-C2orange. In addition to these homologues of alkylbenzenes, tetralin, and naphthalene, the mid-distillate contains some fluorene derivatives and phenanthrene derivatives. The phenanthrene structure appears to be favored over that of anthracene structure (Tissot and Welte, 1978 Speight, 1999). 

Only three phenanthrene glucosides have been identified so far. 2,4,6-Trihydroxyphenanthrene-2-O-glucoside (318) was isolated from a commereial Riesling wine [32] 3,4,6-trihydroxyphenanthrene-3- O-b-D-glucopyranoside (319) was isolated from the rhizome of Dioscorea opposite [163] and denchryside A (336), from the herbs of Dendrobium chrysanthum, a diglycoside identified as 2,6-dihydroxy-1,5,7- trimethoxy-phenanthrene-2-0-[a-L-rhamnopyranosyl-( 1 6)]-Z)-D-glucopyranoside [173]. The new phenanthrene structures have been shown in Fig. (16). 

Recently, our laboratory designed and synthesized several series of new water-soluble phenanthrene-based tylophorine derivatives (PBTs) as potential antitumor agents. These compounds contain a core phenanthrene structure and can be synthesized efficiently in excellent yield. The newly synthesized PBTs were evaluated for cytotoxic activity against the A549 human cancer cell line. Among them, V-(2,3-methylenedioxy-6-methoxy-phenanthr-9-ylmethyl)-L-2-piperidinemethanol (100) and /V- (2,3 - methyl enedioxy - 6- meth oxy-... 

The most important experimental fact, however, reported for any of the miscellaneous bases concerns the unnamed base recently (90) isolated, which accompanies delphinine and staphisine in D. staphisagria. This base, which may not be correctly formulated, on dehydrogenation over selenium jdelds a crystalline hydrocarbon (CisHie), the ultraviolet absorption spectrum of which indicates the presence of a phenanthrene structure. The fact that the presence of a phenanthrene system can be established both in this new base and in staphisine, i.e., in both minor alkaloids accompanying delphinine, whilst delphinine itself does not readily yield a phenanthrene derivative on dehydrogenation (70), should stimulate further research in this field. If the reason for this difference in behavior can be ascertained, it should permit a better imderstanding of the nature of the polycyclic skeleton present in the atisines and in the aconitines and result in a great advance towards the complete elucidation of the structures of the Aconitum and Delphinium alkaloids. 

Only the last method, developed by Rapoport s group [95], is a versatile, chemoselective, and high-yielding. The method is accomplished by adding an alkyl nitrite (2 eq.) to a cold acetone solution of a Pschorr s amine substrate (1 eq.) and sulfuric acid (2 eq.) followed by sodium iodide. Here the iodide serves as a one-electron reductant, which converts an aryldiazonium salt to an aryl radical [95,96]. Then, the fast intramolecular arylation takes place with formation of the phenanthrene structure. While the older Pschorr methods gave very low yields, often under 20%, the Rapoport s method introduced significant improvements as the yields were 45-71% [95]. For example, polymethoxy compound 52 was converted to phenanthrene 53 in 71% yield [95], respectively. Scheme 22. 

Intramolecular oxidative coupling reactions affording the phenanthrene structure were effected with great success by the most common method applying vanadium oxytrifluoride in the presence of BF3 Et20. For example, compound 402 was converted to phenanthrene 403 in 95% yield under very mild reaction conditions, respectively... 

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. 

It proved possible to selectively oxiditively cyclize the two dialkoxyphenyl substituents of polymer 5 with ferric chloride to produce phenanthrene structures (Scheme 17) [118]. Similar cyclizations were performed on di(monoalkoxypheny )-PPVs. 

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